Elan Library Reference

Table of contents

Main topics | Detailed topics

Value data types

Integer

An integer is a whole number, i.e. one that has no fractional part. It may be represented in decimal, hexadecimal or binary:

100100100100100 (decimal), 0x640x640x64&H640x64 (hexadecimal) and 0b11001000b11001000b1100100&B11001000b1100100 (binary) all have the same value.

Its type is IntintintIntegerint.

name
of type		 examples of defining
a literal value
IntintintIntegerint +constant maxNumbername? set to 10literal value or data structure?0+maxNumbername? = 10literal value or data structure? # constant1+const Int maxNumbername? = 10literal value or data structure?;2+Const maxNumbername? = 10literal value or data structure?3+static final Int maxNumbername? = 10literal value or data structure?; // constant4
IntintintIntegerint variable flagsname? set to 0b1100100value or expression?5flagsname? = 0b1100100value or expression? # variable definition6var flagsname? = 0b1100100value or expression?;7Dim flagsname? = &B1100100value or expression? ' variable definition8var flagsname? = 0b1100100value or expression?;9

Function dot methods on an IntintintIntegerint

function
dot method		 argument
types		 return
type		 returns
asBinary (none) StringstrstringStringString string of binary digits representing the argument's integer value
equals IntintintIntegerint BooleanboolboolBooleanboolean trueTruetrueTruetrue if integer and argument values are equal
– falseFalsefalseFalsefalse otherwise
notEqualTo IntintintIntegerint BooleanboolboolBooleanboolean trueTruetrueTruetrue if integer and argument values are unequal
– falseFalsefalseFalsefalse otherwise
toString (none) StringstrstringStringString a string of decimal digits representing the argument's integer value

Notes

Example of base conversion

   ● Functions to return an integer value as a hexadecimal string:

+function hexname?(n as Intparameter definitions?) returns StringType? 1 variable hname? set to ""value or expression?2 +if (n < 1)condition? then 3 assign hvariableName? to "0"value or expression?4 else5 variable mname? set to nvalue or expression?6 +while m > 0condition? 7 assign hvariableName? to hexDigit(m mod 16) + hvalue or expression?8 assign mvariableName? to divAsInt(m, 16)value or expression?9 end while end if return hvalue or expression?10 end function +function hexDigitname?(i as Intparameter definitions?) returns StringType? 11 return "0123456789abcdef".subString(i, i + 1)value or expression?12 end function
+def hexname?(n: intparameter definitions?) -> strType?: # function1 hname? = ""value or expression? # variable definition2 +if (n < 1)condition?: 3 hvariableName? = "0"value or expression? # assignment4 else:5 mname? = nvalue or expression? # variable definition6 +while m > 0condition?: 7 hvariableName? = hexDigit(m % 16) + hvalue or expression? # assignment8 mvariableName? = divAsInt(m, 16)value or expression? # assignment9 # end while # end if return hvalue or expression?10 # end function +def hexDigitname?(i: intparameter definitions?) -> strType?: # function11 return "0123456789abcdef".subString(i, i + 1)value or expression?12 # end function
+static stringType? hexname?(int nparameter definitions?) { // function1 var hname? = ""value or expression?;2 +if ((n < 1)condition?) { 3 hvariableName? = "0"value or expression?; // assignment4 } else {5 var mname? = nvalue or expression?;6 +while (m > 0condition?) { 7 hvariableName? = hexDigit(m % 16) + hvalue or expression?; // assignment8 mvariableName? = divAsInt(m, 16)value or expression?; // assignment9 } // end while } // end if return hvalue or expression?;10 } // end function +static stringType? hexDigitname?(int iparameter definitions?) { // function11 return "0123456789abcdef".subString(i, i + 1)value or expression?;12 } // end function
+Function hexname?(n As Integerparameter definitions?) As StringType? 1 Dim hname? = ""value or expression? ' variable definition2 +If (n < 1)condition? Then 3 hvariableName? = "0"value or expression? ' assignment4 Else5 Dim mname? = nvalue or expression? ' variable definition6 +While m > 0condition? 7 hvariableName? = hexDigit(m Mod 16) + hvalue or expression? ' assignment8 mvariableName? = divAsInt(m, 16)value or expression? ' assignment9 End While End If Return hvalue or expression?10 End Function +Function hexDigitname?(i As Integerparameter definitions?) As StringType? 11 Return "0123456789abcdef".subString(i, i + 1)value or expression?12 End Function
public class Global {

+static StringType? hexname?(int nparameter definitions?) { // function1 var hname? = ""value or expression?;2 +if ((n < 1)condition?) { 3 hvariableName? = "0"value or expression?; // assignment4 } else {5 var mname? = nvalue or expression?;6 +while (m > 0condition?) { 7 hvariableName? = hexDigit(m % 16) + hvalue or expression?; // assignment8 mvariableName? = divAsInt(m, 16)value or expression?; // assignment9 } // end while } // end if return hvalue or expression?;10 } // end function +static StringType? hexDigitname?(int iparameter definitions?) { // function11 return "0123456789abcdef".subString(i, i + 1)value or expression?;12 } // end function
} // end Global

Example of large numbers

   ● This code calculates 2 raised to the power of 50 through 72, and its output is shown below:

+main 13 +for nitem? in range(50, 73)source? 14 variable npname? set to pow(2, n).floor()value or expression?15 call printTabprocedureName?(n.toString().length(), $"{n}"arguments?)16 call printTabprocedureName?(30 - np.toString().length(), $"{np}\n"arguments?)17 end for end main
+def main() -> None: 18 +for nitem? in range(50, 73)source?: 19 npname? = pow(2, n).floor()value or expression? # variable definition20 printTabprocedureName?(n.toString().length(), f"{n}"arguments?) # procedure call21 printTabprocedureName?(30 - np.toString().length(), f"{np}\n"arguments?) # procedure call22 # end for # end main
+static void main() { 23 +foreach (var nitem? in range(50, 73)source?) { 24 var npname? = pow(2, n).floor()value or expression?;25 printTabprocedureName?(n.toString().length(), $"{n}"arguments?); // procedure call26 printTabprocedureName?(30 - np.toString().length(), $"{np}\n"arguments?); // procedure call27 } // end foreach } // end main
+Sub main() 28 +For Each nitem? In range(50, 73)source? 29 Dim npname? = pow(2, n).floor()value or expression? ' variable definition30 printTabprocedureName?(n.toString().length(), $"{n}"arguments?) ' procedure call31 printTabprocedureName?(30 - np.toString().length(), $"{np}\n"arguments?) ' procedure call32 Next n End Sub
+static void main() { 33 +foreach (var nitem? in range(50, 73)source?) { 34 var npname? = pow(2, n).floor()value or expression?;35 printTabprocedureName?(n.toString().length(), String.format("%", n)arguments?); // procedure call36 printTabprocedureName?(30 - np.toString().length(), String.format("%\n", np)arguments?); // procedure call37 } // end foreach } // end main

big integers

Floating point

A floating point number is a decimal number (also known as a Real number) that may have both integer and fractional parts.

Its type is FloatfloatdoubleDoubledouble.

It may be written using exponential (scientific) notation, e.g. 120.0120.0120.0120.0120.0 can be written as 1.20e21.20e21.20e21.20e21.20e2, and 0.0120.0120.0120.0120.012 as 1.20e-21.20e-21.20e-21.20e-21.20e-2

name
of type		 examples of defining
a literal value
FloatfloatdoubleDoubledouble +constant phiname? set to 1.618033988749895literal value or data structure?10+phiname? = 1.618033988749895literal value or data structure? # constant11+const Float phiname? = 1.618033988749895literal value or data structure?;12+Const phiname? = 1.618033988749895literal value or data structure?13+static final Float phiname? = 1.618033988749895literal value or data structure?; // constant14
FloatfloatdoubleDoubledouble variable readingname? set to 1.1e-10value or expression?15readingname? = 1.1e-10value or expression? # variable definition16var readingname? = 1.1e-10value or expression?;17Dim readingname? = 1.1e-10value or expression? ' variable definition18var readingname? = 1.1e-10value or expression?;19

Function dot methods on a FloatfloatdoubleDoubledouble

function
dot method		 argument
types		 return
type		 returns
ceiling (none) IntintintIntegerint the first integral value larger than or equal to the argument's
floating point value
equals FloatfloatdoubleDoubledouble BooleanboolboolBooleanboolean trueTruetrueTruetrue if floating point number and argument values are equal
– falseFalsefalseFalsefalse otherwise
floor (none) IntintintIntegerint the first integral value smaller than or equal to the argument's
floating point value
isInfinite (none) BooleanboolboolBooleanboolean trueTruetrueTruetrue if value would be infinite, e.g. after division by zero
– falseFalsefalseFalsefalse otherwise
isNaN (none) BooleanboolboolBooleanboolean trueTruetrueTruetrue if value is 'NaN', i.e. Not a Number, e.g. 0/0
– falseFalsefalseFalsefalse otherwise
notEqualTo FloatfloatdoubleDoubledouble BooleanboolboolBooleanboolean trueTruetrueTruetrue if floating point number and argument values are unequal
– falseFalsefalseFalsefalse otherwise
round IntintintIntegerint FloatfloatdoubleDoubledouble the value rounded (up or down as appropriate) to the
number of decimal places specified in the argument
toString (none) StringstrstringStringString a string of decimal digits and decimal point representing the argument's floating point value

Notes

Boolean

A Boolean value is either trueTruetrueTruetrue or falseFalsefalseFalsefalse.

Its type is BooleanboolboolBooleanboolean.

The words trueTruetrueTruetrue and falseFalsefalseFalsefalse must be written in lower case.

name
of type		 examples of defining
a literal value
BooleanboolboolBooleanboolean variable donename? set to truevalue or expression?25donename? = Truevalue or expression? # variable definition26var donename? = truevalue or expression?;27Dim donename? = Truevalue or expression? ' variable definition28var donename? = truevalue or expression?;29

Function dot methods on a BooleanboolboolBooleanboolean

function
dot methods		 argument
types		 return
type		 returns
equals BooleanboolboolBooleanboolean BooleanboolboolBooleanboolean trueTruetrueTruetrue if the truth value and argument are equal
– falseFalsefalseFalsefalse otherwise
notEqualTo BooleanboolboolBooleanboolean BooleanboolboolBooleanboolean trueTruetrueTruetrue if the truth value and argument are unequal
– falseFalsefalseFalsefalse otherwise
toString (none) StringstrstringStringString String "true" if trueTruetrueTruetrue,
"false" if falseFalsefalseFalsefalse

Reference data types

String

The data type StringstrstringStringString represents text, i.e. a sequence of zero or more characters.

name
of type		 examples of defining
a literal value		 details
StringstrstringStringString +constant titlename? set to "Ulysses"literal value or data structure?30+titlename? = "Ulysses"literal value or data structure? # constant31+const String titlename? = "Ulysses"literal value or data structure?;32+Const titlename? = "Ulysses"literal value or data structure?33+static final String titlename? = "Ulysses"literal value or data structure?; // constant34 delimited by double quotes
StringstrstringStringString variable quotename? set to "'Hello', she said"value or expression?35quotename? = "'Hello', she said"value or expression? # variable definition36var quotename? = "'Hello', she said"value or expression?;37Dim quotename? = "'Hello', she said"value or expression? ' variable definition38var quotename? = "'Hello', she said"value or expression?;39 ' may be used in a string delimited by "
StringstrstringStringString variable emptyStringname? set to ""value or expression?40emptyStringname? = ""value or expression? # variable definition41var emptyStringname? = ""value or expression?;42Dim emptyStringname? = ""value or expression? ' variable definition43var emptyStringname? = ""value or expression?;44 a zero-length, or 'empty', string

Character sets

When typing from the keyboard into a literal string all the basic ASCII characters (0x20 to 0x7e) and '£' can be input.

You cannot use Alt+numeric-keypad to enter accented letters or other special characters in the extended ASCII range (0x80 to 0xff).

You can, however, copy any text from outside Elan and paste it into a string, whether ASCII, extended ASCII or UTF-8 encoded.

To insert a character from the full range, you use its Unicode (codepoint) value, in decimal or hexadecimal, by means of function unicode :

print($"Spanish introduces a question with {unicode(191)}")print(f"Spanish introduces a question with {unicode(191)}")print($"Spanish introduces a question with {unicode(191)}")print($"Spanish introduces a question with {unicode(191)}")print(String.format("Spanish introduces a question with %", unicode(191))) ⟶Spanish introduces a question with ¿
print($"This is an up arrow: {unicode(0x2191)}")print(f"This is an up arrow: {unicode(0x2191)}")print($"This is an up arrow: {unicode(0x2191)}")print($"This is an up arrow: {unicode(&H2191)}")print(String.format("This is an up arrow: %", unicode(0x2191))) ⟶This is an up arrow: ↑

These examples 'interpolate' the output of function unicode by using a $ before the string and curly braces within it. See Interpolated fields ).

Manipulating strings

Strings can be built from other strings by concatenation using the plus operator, for example:

print("Hello " + "world")print("Hello " + "world")print("Hello " + "world")print("Hello " + "world")print("Hello " + "world") ⟶Hello world

A newline may be inserted within a string with \n:

print("Hello\nworld")print("Hello\nworld")print("Hello\nworld")print("Hello\nworld")print("Hello\nworld")⟶Hello
world

When editing and you leave the field, the newline will be implicitly applied in your code.

As in most languages, strings are immutable. When you apply any operation or function with the intent of modifying an existing StringstrstringStringString, the existing StringstrstringStringString is never changed. Instead, the operation or function will return a new StringstrstringStringString that is based on the original, but with the specified differences.

You can loop through a StringstrstringStringString picking each of its characters sequentially using the for loop .

Function dot methods on a String

function
dot method		 argument
types		 return
type		 returns
asRegExp (none) RegExpRegExpRegExpRegExpRegExp a new string that is a a converted to a regular expression:
no check is made of whether the result is a valid regular expression
asUnicode (none) IntintintIntegerint the Unicode value of the first character of the string
(To convert a Unicode value into a string, use function unicode )
contains (none) BooleanboolboolBooleanboolean trueTruetrueTruetrue if the string contains the substring specified as the argument
– falseFalsefalseFalsefalse otherwise
equals StringstrstringStringString BooleanboolboolBooleanboolean trueTruetrueTruetrue if the string and argument are equal
– falseFalsefalseFalsefalse otherwise
notEqualTo StringstrstringStringString BooleanboolboolBooleanboolean trueTruetrueTruetrue if the string and argument are unequal
– falseFalsefalseFalsefalse otherwise
indexOf StringstrstringStringString IntintintIntegerint index of the first instance of the argument (substring) within the string
If it is not present, -1 is returned
isAfter StringstrstringStringString BooleanboolboolBooleanboolean trueTruetrueTruetrue if alphabetic comparison finds the string comes strictly 'after' the argument string
– falseFalsefalseFalsefalse otherwise
isAfterOrSameAs StringstrstringStringString BooleanboolboolBooleanboolean trueTruetrueTruetrue if alphabetic comparison finds the string comes 'after' or equals the argument string
– falseFalsefalseFalsefalse otherwise
isBefore StringstrstringStringString BooleanboolboolBooleanboolean trueTruetrueTruetrue if alphabetic comparison finds the string comes strictly 'before' the argument string
– falseFalsefalseFalsefalse otherwise
isBeforeOrSameAs StringstrstringStringString BooleanboolboolBooleanboolean trueTruetrueTruetrue if alphabetic comparison finds the string comes 'before' or equals the argument string
– falseFalsefalseFalsefalse otherwise
length (none) IntintintIntegerint the number of characters in the string
lowerCase (none) StringstrstringStringString a new string with the original rendered in lower case
matchesRegExp RegExpRegExpRegExpRegExpRegExp BooleanboolboolBooleanboolean trueTruetrueTruetrue if the string matches the regular expression
– falseFalsefalseFalsefalse otherwise
replace StringstrstringStringString, StringstrstringStringString StringstrstringStringString a new string with all occurrences of the first argument string replaced by the second argument string
split StringstrstringStringString List<of String>list[str]List<string>List(Of String)List<String> a ListlistListListList of the substrings found between occurrences of the argument string
if the argument is the empty string then the ListlistListListList is of all the individual characters
subString IntintintIntegerint, IntintintIntegerint StringstrstringStringString a new string that is the substring specified by the two positive integers (m,n) where
m indexes the first character of the substring required (counting from 0) and
n indexes the character after the last character required (exclusive index)
if m ≥ n the result is the empty string
toString (none) StringstrstringStringString the string itself
trim (none) StringstrstringStringString a new string with leading and trailing spaces removed
upperCase (none) StringstrstringStringString a new string with the original rendered in upper case

Interpolated fields in strings

Strings support interpolation, that is you can insert the values of variables or simple expressions within the string by enclosing them in curly braces and prefixing the string with a $:

If aaaaa and bbbbb have values 3 and 17:

print($"{a} times {b} equals {a*b}")print(f"{a} times {b} equals {a*b}")print($"{a} times {b} equals {a*b}")print($"{a} times {b} equals {a*b}")print(String.format("% times % equals %", a, b, a*b)) ⟶3 times 17 equals 51

If velocityvelocityvelocityvelocityvelocity and fuelfuelfuelfuelfuel have values 3.0 and 50.4:

assign messagevariableName? to $"LANDED SAFELY AT SPEED {(velocity*100).floor()} FUEL {fuel.floor()}"value or expression?45messagevariableName? = f"LANDED SAFELY AT SPEED {(velocity*100).floor()} FUEL {fuel.floor()}"value or expression? # assignment46messagevariableName? = $"LANDED SAFELY AT SPEED {(velocity*100).floor()} FUEL {fuel.floor()}"value or expression?; // assignment47messagevariableName? = $"LANDED SAFELY AT SPEED {(velocity*100).floor()} FUEL {fuel.floor()}"value or expression? ' assignment48messagevariableName? = String.format("LANDED SAFELY AT SPEED % FUEL %", (velocity*100).floor(), fuel.floor())value or expression?; // assignment49 print(message)print(message)print(message)print(message)print(message)


⟶
LANDED SAFELY AT SPEED 300 FUEL 50

And for the area of a circle:

+main 38 variable rname? set to 2.0value or expression?39 print($"area = {(pi*r*r).round(2)}"value or expression?)40 end main
+def main() -> None: 41 rname? = 2.0value or expression? # variable definition42 print(f"area = {(pi*r*r).round(2)}"value or expression?)43 # end main
+static void main() { 44 var rname? = 2.0value or expression?;45 Console.WriteLine($"area = {(pi*r*r).round(2)}"value or expression?); // print statement46 } // end main
+Sub main() 47 Dim rname? = 2.0value or expression? ' variable definition48 Console.WriteLine($"area = {(pi*r*r).round(2)}"value or expression?) ' print statement49 End Sub
+static void main() { 50 var rname? = 2.0value or expression?;51 System.out.println(String.format("area = %", (pi*r*r).round(2))value or expression?); // print statement52 } // end main


⟶

area = 12.57

Standard data structures

Elan has two mutable data structure types ListlistListListList and DictionaryDictionaryDictionaryDictionaryDictionary, and three immutable data structure types HashSetHashSetHashSetHashSetHashSet, StackStackStackStackStack and QueueQueueQueueQueueQueue.

The contents of these structures are referred to as items (or sometimes elements).

The values of items in a mutable structure may be changed directly by calling the various procedure dot methods defined for each structure type.

The values of items in an immutable structure cannot be changed directly, and so have no procedure dot methods defined for them: rather, the methods called on them create new copies of the structures containing specified changes.

Since procedure methods may be called only from within the main routine or a procedure, it is also possible to make changes via function dot methods, which return a copy of the data structure with specified changes: that is why all such methods have names starting 'with'.

Immutable data structures are intended specifically to facilitate the functional programming paradigm, but some are also useful within other programming paradigms.

All six contain values (and keys in the case of a DictionaryDictionaryDictionaryDictionaryDictionary) of only a single type, that type being specified either explicitly (as in <of IntintintIntegerint>), or implicitly if the structure is created using a literal definition.

This table summarises the creation and reference to these structures. Details of their methods follow.

List Dictionary HashSet Stack Queue
mutability Mutable Mutable Immutable Immutable Immutable
type form List<of Type>list[Type]List<Type>List(Of Type)List<Type>
The type of item can be any, including ListlistListListList for 'jagged' data		 new codenew codenew codenew code
public class Global {

new code
} // end Global
keyTypekeyTypekeyTypekeyTypekeyType is IntintintIntegerint, FloatfloatdoubleDoubledouble, StringstrstringStringString or BooleanboolboolBooleanboolean
valueTypevalueTypevalueTypevalueTypevalueType may be any type		 HashSet<of Type>HashSet[Type]HashSet<Type>HashSet(Of Type)HashSet<Type>
The type of the item must be immutable		 Stack<of Type>Stack[Type]Stack<Type>Stack(Of Type)Stack<Type>
The type of the item must be immutable		 Queue<of Type>Queue[Type]Queue<Type>Queue(Of Type)Queue<Type>
The type of the item must be immutable
sizeDynamicDynamicDynamicDynamicDynamic
literal definition [2, 3, 5, 7, 11][2, 3, 5, 7, 11]new [] {2, 3, 5, 7, 11}{2, 3, 5, 7, 11}list(2, 3, 5, 7, 11) Not available Only as converted from a literal ListlistListListList
e.g. ["a", "b", "c"].asSet()["a", "b", "c"].asSet()new [] {"a", "b", "c"}.asSet(){"a", "b", "c"}.asSet()list("a", "b", "c").asSet()		 Not available Not available
create empty new List<of Type>()list[Type]()new List<Type>()New List(Of Type)()new List<Type>() new codenew codenew codenew code
public class Global {

new code
} // end Global		 new HashSet<of Type>()HashSet[Type]()new HashSet<Type>()New HashSet(Of Type)()new HashSet<Type>() new Stack<of Type>()Stack[Type]()new Stack<Type>()New Stack(Of Type)()new Stack<Type>() new Queue<of Type>()Queue[Type]()new Queue<Type>()New Queue(Of Type)()new Queue<Type>()
create initialised createPopulatedList(number, value)createPopulatedList(number, value)createPopulatedList(number, value)createPopulatedList(number, value)createPopulatedList(number, value)
createPopulatedListofLists(cols, rows, value)createPopulatedListofLists(cols, rows, value)createPopulatedListofLists(cols, rows, value)createPopulatedListofLists(cols, rows, value)createPopulatedListofLists(cols, rows, value) 		createDictionary(List<of (keyType, valueType)>) Not available Not available Not available
read by index li[2]li[2]li[2]li[2]li[2] d["b"]d["b"]d["b"]d["b"]d["b"] not available not available not available
read by index range li.subList(3, 5)li.subList(3, 5)li.subList(3, 5)li.subList(3, 5)li.subList(3, 5)
lower bound is inclusive from 0
upper bound is exclusive		 not available not available not available not available
procedure methods to mutate contents see Procedure methods on a ListlistListListList see Procedure methods on a Dictionary not available not available not available
function dot methods see Function dot methods on a ListlistListListList see Function dot methods on a Dictionary see Function dot methods on a Set see Function dot methods on a Stack see Function dot methods on a Queue

List

The ListlistListListList type defines a data structure containing n items of any single type, including basic value types, structure types such as ListlistListListList, and user-defined types such as a class.

Items in a ListlistListListList of n items are indexed from 0 to n-1.

To create a ListlistListListList, use either of:

The item at index ixixixixix in ListlistListListList aListaListaListaListaList can then be changed using an assign variable instruction and a valid index value in square brackets:

A ListlistListListList's size can be dynamically changed using the procedure methods listed below.

Deconstructing a List

A ListlistListListList may be split (deconstructed) into new named values using indexes and the methods head, tail and subList :

In all these cases the items indexed must exist, else a runtime error will stop the program.

Lists of lists

Two dimensional arrays

Understood as a grid, a 2D array is a ListlistListListList of 'columns' each of which is a ListlistListListList of 'row' items, i.e. it is a ListlistListListList of ListlistListListLists in which the column number is the x coordinate, and the row number is the y coordinate.

To create a 2D array that holds a value of a single type in every cell, you define such a ListlistListListList of ListlistListListLists thus:

The item at index ixixixixix,iyiyiyiyiy in a 2D array can be accessed and changed using its two coordinates in square brackets:

Higher dimensional arrays

For a 3D array, you can, for example, define:

and refer to a cell using three indexes in square brackets.

Procedure methods on a ListlistListListList

Where an argument provides a new value for an item in a ListlistListListList, that value must be of the same type as defined for the ListlistListListList's items.

procedure
method		 arguments action
append value of ListlistListListList item's type the item is added to the end of the ListlistListListList
appendList ListlistListListList the argument ListlistListListList is added to the end of the ListlistListListList
initialise IntintintIntegerint,
value of ListlistListListList item's type		 specify the number (> 0) of items in the ListlistListListList,
and an initial value for every item.
May be called at any time to redefine the ListlistListListList's size and initial values.
insert IntintintIntegerint,
value of ListlistListListList item's type		 the item is inserted at the index given.
If the index is negative it is counted from the end
If the index is greater than the ListlistListListList's length, the item is inserted at the end
prepend value of ListlistListListList item's type the item is is added to the start of the ListlistListListList
prependList ListlistListListList the argument ListlistListListList is added to the start of the ListlistListListList
removeAll value of ListlistListListList item's type delete all items equal to the given item
removeAt IntintintIntegerint delete the item at the argument index
removeFirst value of ListlistListListList item's type delete the first item equal to the given value

Function dot methods on a ListlistListListList

function
dot method		 arguments return
type		 returns
asSet (none) HashSetHashSetHashSetHashSetHashSet a new Set containing all the unique items in the ListlistListListList
contains value BooleanboolboolBooleanboolean trueTruetrueTruetrue if the ListlistListListList contains the specified item
– falseFalsefalseFalsefalse otherwise
equals ListlistListListList BooleanboolboolBooleanboolean trueTruetrueTruetrue if ListlistListListList and argument are identical
– falseFalsefalseFalsefalse otherwise
filter lambdalambdalambdalambdalambda ListlistListListList a new ListlistListListList obtained from applying a lambda to the input ListlistListListList
see filter in HoFs
indexOf value of ListlistListListList item's type IntintintIntegerint the index of the first occurrence of the argument value in the ListlistListListList,
or -1 if no match is found
join List<of String>list[str]List<string>List(Of String)List<String> StringstrstringStringString a single String that joins all the items in the ListlistListListList,
with the specified String (which can be empty) inserted between the items
length (none) IntintintIntegerint the number of items in the ListlistListListList
map lambdalambdalambdalambdalambda ListlistListListList a new ListlistListListList obtained from applying a lambda to the input ListlistListListList
see map in HoFs
maxBy lambdalambdalambdalambdalambda ListlistListListList item's type the ListlistListListList item corresponding to the maximum of the values returned by a lambda
see maxBy in HoFs
minBy lambdalambdalambdalambdalambda ListlistListListList item's type the ListlistListListList item corresponding to the minimum of the values returned by a lambda
see minBy in HoFs
notEqualTo ListlistListListList BooleanboolboolBooleanboolean trueTruetrueTruetrue if ListlistListListList and argument differ l
– falseFalsefalseFalsefalse otherwise
orderBy lambdalambdalambdalambdalambda ListlistListListList a new ListlistListListList with the items ordered according to the value returned by a lambda
reduce item of ListlistListListList item's type,
lambdalambdalambdalambdalambda		 return type of lambda the final value obtained by applying a lambda cumulatively to each item in the input ListlistListListList
taking account of the first argument as an initial (and default return) value
see reduce in HoFs
subList IntintintIntegerint, IntintintIntegerint ListlistListListList a new ListlistListListList that contains the items specified by the two positive integers (m,n) where
m indexes the first item of the ListlistListListList required (counting from 0) and
n indexes the item after the last item required (exclusive index)
if m ≥ n the result is the empty ListlistListListList
tail (none) ListlistListListList item's type all items except the first item in the ListlistListListList (i.e. index = 1..n, which must exist)
toString (none) StringstrstringStringString a String that is a comma+space-separated list of the ListlistListListList's items, enclosed in square brackets
withAppend item of ListlistListListList item's type ListlistListListList a new ListlistListListList lengthened with the item added after the end
withAppendList ListlistListListList of same type ListlistListListList a new ListlistListListList lengthened by appending the given ListlistListListList
withInsert IntintintIntegerint,
value of ListlistListListList item's type		 ListlistListListList a new ListlistListListList with the item inserted after the item at the given index position
withPrepend value of ListlistListListList item's type ListlistListListList a new ListlistListListList lengthened with the item added before the beginning
withPrependList ListlistListListList of same type ListlistListListList a new ListlistListListList lengthened by prepending the given ListlistListListList
withRemoveAll value of ListlistListListList item's type ListlistListListList a new ListlistListListList with items equal to the given item removed
withRemoveAt IntintintIntegerint ListlistListListList a new ListlistListListList with the item at the given index removed
withRemoveFirst value of ListlistListListList item's type ListlistListListList a new ListlistListListList with the first item equal to the given item removed
withPut (supersedes deprecated withSet) IntintintIntegerint,
value of ListlistListListList item's type		 ListlistListListList a new ListlistListListList with the item replacing that at the given index

Dictionary

A DictionaryDictionaryDictionaryDictionaryDictionary is like a ListlistListListList whose items are pairs but, instead of having a numeric index, each item has a key plus an associated value, i.e. a Dictionary is a set of key:value pairs.

The key's type must be one of IntintintIntegerint, FloatfloatdoubleDoubledouble, StringstrstringStringString or BooleanboolboolBooleanboolean. The values may be of any type. The types of both keys and values are fixed when the Dictionary is created.

You refer to a dictionary item using one of its (unique) keys, e.g. in a Dictionary<of String, Int>Dictionary[str, int]Dictionary<string, int>Dictionary(Of String, Integer)Dictionary<String, int> named birthdaysbirthdaysbirthdaysbirthdaysbirthdays whose keys are names and whose values are birth year, you might refer to birthdays["Shakespeare"]birthdays["Shakespeare"]birthdays["Shakespeare"]birthdays["Shakespeare"]birthdays["Shakespeare"] and retrieve the value 1564.

Example using DictionaryDictionaryDictionaryDictionaryDictionary

   ● Define a constant dictionary for reference throughout the program:

Procedure greekLetters sets up the key:value pairs, procedure printD shows how a procedure can use the dictionary, and function getDItem retrieves a value given a key.

+main 1 variable dLname? set to new Dictionary<of String, Int>()value or expression?2 variable dLRefname? set to new AsRef<of Dictionary<of String, Int>>(dL)value or expression?3 call greekLettersprocedureName?(dLRefarguments?)4 assign dLvariableName? to dLRef.value()value or expression?5 print(dLvalue or expression?)6 call printDprocedureName?(dLarguments?)7 print(getDItem(dL, "alpha")value or expression?)8 end main +procedure printDname?(dL as Dictionary<of String, Int>parameter definitions?) 9 print(dLvalue or expression?)10 end procedure +function getDItemname?(dL as Dictionary<of String, Int>, k as Stringparameter definitions?) returns IntType? 11 return dL[k]value or expression?12 end function +procedure printDItemname?(dL as Dictionary<of String, Int>, k as Stringparameter definitions?) 13 print(dL[k]value or expression?)14 end procedure +procedure greekLettersname?(d as AsRef<of Dictionary<of String, Int>>parameter definitions?) 15 variable diname? set to new Dictionary<of String, Int>()value or expression?16 assign di["alpha"]variableName? to 1value or expression?17 assign di["beta"]variableName? to 2value or expression?18 assign di["gamma"]variableName? to 3value or expression?19 call d.putprocedureName?(diarguments?)20 end procedure
+def main() -> None: 1 dLname? = Dictionary[str, int]()value or expression? # variable definition2 dLRefname? = AsRef[Dictionary[str, int]](dL)value or expression? # variable definition3 greekLettersprocedureName?(dLRefarguments?) # procedure call4 dLvariableName? = dLRef.value()value or expression? # assignment5 print(dLvalue or expression?)6 printDprocedureName?(dLarguments?) # procedure call7 print(getDItem(dL, "alpha")value or expression?)8 # end main +def printDname?(dL: Dictionary[str, int]parameter definitions?) -> None: # procedure9 print(dLvalue or expression?)10 # end procedure +def getDItemname?(dL: Dictionary[str, int], k: strparameter definitions?) -> intType?: # function11 return dL[k]value or expression?12 # end function +def printDItemname?(dL: Dictionary[str, int], k: strparameter definitions?) -> None: # procedure13 print(dL[k]value or expression?)14 # end procedure +def greekLettersname?(d: AsRef[Dictionary[str, int]]parameter definitions?) -> None: # procedure15 diname? = Dictionary[str, int]()value or expression? # variable definition16 di["alpha"]variableName? = 1value or expression? # assignment17 di["beta"]variableName? = 2value or expression? # assignment18 di["gamma"]variableName? = 3value or expression? # assignment19 d.putprocedureName?(diarguments?) # procedure call20 # end procedure main()
+static void main() { 1 var dLname? = new Dictionary<string, int>()value or expression?;2 var dLRefname? = new AsRef<Dictionary<string, int>>(dL)value or expression?;3 greekLettersprocedureName?(dLRefarguments?); // procedure call4 dLvariableName? = dLRef.value()value or expression?; // assignment5 Console.WriteLine(dLvalue or expression?); // print statement6 printDprocedureName?(dLarguments?); // procedure call7 Console.WriteLine(getDItem(dL, "alpha")value or expression?); // print statement8 } // end main +static void printDname?(Dictionary<string, int> dLparameter definitions?) { // procedure9 Console.WriteLine(dLvalue or expression?); // print statement10 } // end procedure +static intType? getDItemname?(Dictionary<string, int> dL, string kparameter definitions?) { // function11 return dL[k]value or expression?;12 } // end function +static void printDItemname?(Dictionary<string, int> dL, string kparameter definitions?) { // procedure13 Console.WriteLine(dL[k]value or expression?); // print statement14 } // end procedure +static void greekLettersname?(AsRef<Dictionary<string, int>> dparameter definitions?) { // procedure15 var diname? = new Dictionary<string, int>()value or expression?;16 di["alpha"]variableName? = 1value or expression?; // assignment17 di["beta"]variableName? = 2value or expression?; // assignment18 di["gamma"]variableName? = 3value or expression?; // assignment19 d.putprocedureName?(diarguments?); // procedure call20 } // end procedure
+Sub main() 1 Dim dLname? = New Dictionary(Of String, Integer)()value or expression? ' variable definition2 Dim dLRefname? = New AsRef(Of Dictionary(Of String, Integer))(dL)value or expression? ' variable definition3 greekLettersprocedureName?(dLRefarguments?) ' procedure call4 dLvariableName? = dLRef.value()value or expression? ' assignment5 Console.WriteLine(dLvalue or expression?) ' print statement6 printDprocedureName?(dLarguments?) ' procedure call7 Console.WriteLine(getDItem(dL, "alpha")value or expression?) ' print statement8 End Sub +Sub printDname?(dL As Dictionary(Of String, Integer)parameter definitions?) ' procedure9 Console.WriteLine(dLvalue or expression?) ' print statement10 End Sub +Function getDItemname?(dL As Dictionary(Of String, Integer), k As Stringparameter definitions?) As IntegerType? 11 Return dL(k)value or expression?12 End Function +Sub printDItemname?(dL As Dictionary(Of String, Integer), k As Stringparameter definitions?) ' procedure13 Console.WriteLine(dL(k)value or expression?) ' print statement14 End Sub +Sub greekLettersname?(d As AsRef(Of Dictionary(Of String, Integer))parameter definitions?) ' procedure15 Dim diname? = New Dictionary(Of String, Integer)()value or expression? ' variable definition16 di("alpha")variableName? = 1value or expression? ' assignment17 di("beta")variableName? = 2value or expression? ' assignment18 di("gamma")variableName? = 3value or expression? ' assignment19 d.putprocedureName?(diarguments?) ' procedure call20 End Sub
public class Global {

+static void main() { 1 var dLname? = new Dictionary<String, int>()value or expression?;2 var dLRefname? = new AsRef<Dictionary<String, int>>(dL)value or expression?;3 greekLettersprocedureName?(dLRefarguments?); // procedure call4 dLvariableName? = dLRef.value()value or expression?; // assignment5 System.out.println(dLvalue or expression?); // print statement6 printDprocedureName?(dLarguments?); // procedure call7 System.out.println(getDItem(dL, "alpha")value or expression?); // print statement8 } // end main +static void printDname?(Dictionary<String, int> dLparameter definitions?) { // procedure9 System.out.println(dLvalue or expression?); // print statement10 } // end procedure +static intType? getDItemname?(Dictionary<String, int> dL, String kparameter definitions?) { // function11 return dL[k]value or expression?;12 } // end function +static void printDItemname?(Dictionary<String, int> dL, String kparameter definitions?) { // procedure13 System.out.println(dL[k]value or expression?); // print statement14 } // end procedure +static void greekLettersname?(AsRef<Dictionary<String, int>> dparameter definitions?) { // procedure15 var diname? = new Dictionary<String, int>()value or expression?;16 di["alpha"]variableName? = 1value or expression?; // assignment17 di["beta"]variableName? = 2value or expression?; // assignment18 di["gamma"]variableName? = 3value or expression?; // assignment19 d.putprocedureName?(diarguments?); // procedure call20 } // end procedure
} // end Global

   ● Define a constant Dictionary for reference throughout the program in a way suitable for functional programming, by using the HoF reduce in a function that creates the Dictionary from a List of key:value pairs as Tuples:

+main 1 variable diname? set to createDictionary([("alpha", 1), ("beta", 2), ("gamma", 3)])value or expression?2 print(di["beta"]value or expression?)3 end main +function createDictionaryname?(kvps as List<of (String, Int)>parameter definitions?) returns Dictionary<of String, Int>Type? 4 let dname? be new Dictionary<of String, Int>()value or expression?5 return kvps.reduce(d, lambda d as Dictionary<of String, Int>, kvp as (String, Int) => d.withPut(kvp.item_0, kvp.item_1))value or expression?6 end function
+def main() -> None: 1 diname? = createDictionary([("alpha", 1), ("beta", 2), ("gamma", 3)])value or expression? # variable definition2 print(di["beta"]value or expression?)3 # end main +def createDictionaryname?(kvps: list[tuple[str, int]]parameter definitions?) -> Dictionary[str, int]Type?: # function4 dname? = Dictionary[str, int]()value or expression? # let5 return kvps.reduce(d, lambda d: Dictionary[str, int], kvp: tuple[str, int]: d.withPut(kvp.item_0, kvp.item_1))value or expression?6 # end function main()
+static void main() { 1 var diname? = createDictionary(new [] {("alpha", 1), ("beta", 2), ("gamma", 3)})value or expression?;2 Console.WriteLine(di["beta"]value or expression?); // print statement3 } // end main +static Dictionary<string, int>Type? createDictionaryname?(List<(string, int)> kvpsparameter definitions?) { // function4 var dname? = new Dictionary<string, int>()value or expression?; // let5 return kvps.reduce(d, Dictionary<string, int> d, (string, int) kvp => d.withPut(kvp.item_0, kvp.item_1))value or expression?;6 } // end function
+Sub main() 1 Dim diname? = createDictionary({("alpha", 1), ("beta", 2), ("gamma", 3)})value or expression? ' variable definition2 Console.WriteLine(di("beta")value or expression?) ' print statement3 End Sub +Function createDictionaryname?(kvps As List(Of (String, Integer))parameter definitions?) As Dictionary(Of String, Integer)Type? 4 Dim dname? = New Dictionary(Of String, Integer)()value or expression? ' let5 Return kvps.reduce(d, Function (d As Dictionary(Of String, Integer), kvp As (String, Integer)) d.withPut(kvp.item_0, kvp.item_1))value or expression?6 End Function
public class Global {

+static void main() { 1 var diname? = createDictionary(list(("alpha", 1), ("beta", 2), ("gamma", 3)))value or expression?;2 System.out.println(di["beta"]value or expression?); // print statement3 } // end main +static Dictionary<String, int>Type? createDictionaryname?(List<(String, int)> kvpsparameter definitions?) { // function4 var dname? = new Dictionary<String, int>()value or expression?; // let5 return kvps.reduce(d, (Dictionary<String, int> d, (String, int) kvp) -> d.withPut(kvp.item_0, kvp.item_1))value or expression?;6 } // end function
} // end Global

Procedure method on a DictionaryDictionaryDictionaryDictionaryDictionary

procedure
method		 argument
types		 action
removeAt key's type delete the key:pair at the given key (if it exists)

Function dot methods on a DictionaryDictionaryDictionaryDictionaryDictionary

function
dot method		 argument
types		 return
type		 returns
equals DictionaryDictionaryDictionaryDictionaryDictionary BooleanboolboolBooleanboolean trueTruetrueTruetrue if dictionary and argument are identical
– falseFalsefalseFalsefalse otherwise
hasKey item of Dictionary key's type BooleanboolboolBooleanboolean trueTruetrueTruetrue if the Dictionary contains the given key
– falseFalsefalseFalsefalse otherwise
keys (none) ListlistListListList a ListlistListListList containing the keys
notEqualTo DictionaryDictionaryDictionaryDictionaryDictionary BooleanboolboolBooleanboolean trueTruetrueTruetrue if dictionary and argument differ
– falseFalsefalseFalsefalse otherwise
toString (none) StringstrstringStringString a string that is a comma+space-separated list of the Dictionary's key:value pairs, enclosed in square brackets
values (none) ListlistListListList a ListlistListListList containing the values
withPut (supersedes deprecated withSet) item of Dictionary key's type,
item of Dictionary value's type		 DictionaryDictionaryDictionaryDictionaryDictionary a new Dictionary with the value replacing what was at the specified key
withRemoveAt item of Dictionary key's type DictionaryDictionaryDictionaryDictionaryDictionary a new Dictionary with the key:value pair removed from the specified key

HashSet

A HashSetHashSetHashSetHashSetHashSet is a standard data structure containing set members, that works somewhat like a ListlistListListList with two important differences:

This enables a HashSet to work like a mathematical set so that it is possible to perform standard set operations such as union and intersection.

When creating a HashSetHashSetHashSetHashSetHashSet, the type of its members must be specified in the form HashSet<of String>HashSet[str]HashSet<string>HashSet(Of String)HashSet<String>

You can add members: either individually with add, or many with addFromList. And you can create a new HashSetHashSetHashSetHashSetHashSet from an existing ListlistListListList by calling asSet on it.

Example of creating a HashSetHashSetHashSetHashSetHashSet from a literal ListlistListListList and changing its content:

+main 7 variable stname? set to new HashSet<of Int>()value or expression?8 assign stvariableName? to st.addFromList([3, 5, 7])value or expression?9 print(st.length()value or expression?)10 assign stvariableName? to st.add(7)value or expression?11 assign stvariableName? to st.remove(3)value or expression?12 print(st.length()value or expression?)13 assign stvariableName? to st.remove(3)value or expression?14 print(st.length()value or expression?)15 print(stvalue or expression?)16 end main
+def main() -> None: 17 stname? = HashSet[int]()value or expression? # variable definition18 stvariableName? = st.addFromList([3, 5, 7])value or expression? # assignment19 print(st.length()value or expression?)20 stvariableName? = st.add(7)value or expression? # assignment21 stvariableName? = st.remove(3)value or expression? # assignment22 print(st.length()value or expression?)23 stvariableName? = st.remove(3)value or expression? # assignment24 print(st.length()value or expression?)25 print(stvalue or expression?)26 # end main
+static void main() { 27 var stname? = new HashSet<int>()value or expression?;28 stvariableName? = st.addFromList(new [] {3, 5, 7})value or expression?; // assignment29 Console.WriteLine(st.length()value or expression?); // print statement30 stvariableName? = st.add(7)value or expression?; // assignment31 stvariableName? = st.remove(3)value or expression?; // assignment32 Console.WriteLine(st.length()value or expression?); // print statement33 stvariableName? = st.remove(3)value or expression?; // assignment34 Console.WriteLine(st.length()value or expression?); // print statement35 Console.WriteLine(stvalue or expression?); // print statement36 } // end main
+Sub main() 37 Dim stname? = New HashSet(Of Integer)()value or expression? ' variable definition38 stvariableName? = st.addFromList({3, 5, 7})value or expression? ' assignment39 Console.WriteLine(st.length()value or expression?) ' print statement40 stvariableName? = st.add(7)value or expression? ' assignment41 stvariableName? = st.remove(3)value or expression? ' assignment42 Console.WriteLine(st.length()value or expression?) ' print statement43 stvariableName? = st.remove(3)value or expression? ' assignment44 Console.WriteLine(st.length()value or expression?) ' print statement45 Console.WriteLine(stvalue or expression?) ' print statement46 End Sub
+static void main() { 47 var stname? = new HashSet<int>()value or expression?;48 stvariableName? = st.addFromList(list(3, 5, 7))value or expression?; // assignment49 System.out.println(st.length()value or expression?); // print statement50 stvariableName? = st.add(7)value or expression?; // assignment51 stvariableName? = st.remove(3)value or expression?; // assignment52 System.out.println(st.length()value or expression?); // print statement53 stvariableName? = st.remove(3)value or expression?; // assignment54 System.out.println(st.length()value or expression?); // print statement55 System.out.println(stvalue or expression?); // print statement56 } // end main


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[5, 7]

Function dot methods on a HashSetHashSetHashSetHashSetHashSet

function
dot method		 argument
types		 return
type		 returns
add value
(of HashSetHashSetHashSetHashSetHashSet members' type)		 HashSetHashSetHashSetHashSetHashSet a new Set extended with the item, provided it differs from all of the Set's current members
addFromList ListlistListListList HashSetHashSetHashSetHashSetHashSet a new Set extended with those items from the ListlistListListList that are not already in the Set
asList (none) ListlistListListList a ListlistListListList containing the Set's members as ListlistListListList items
contains value
(of HashSetHashSetHashSetHashSetHashSet members' type)		 BooleanboolboolBooleanboolean trueTruetrueTruetrue if the Set contains the item
– falseFalsefalseFalsefalse otherwise
difference HashSetHashSetHashSetHashSetHashSet HashSetHashSetHashSetHashSetHashSet a Set containing those members of the Set that do not occur in the argument Set
equals HashSetHashSetHashSetHashSetHashSet BooleanboolboolBooleanboolean trueTruetrueTruetrue if Set and argument Set contain identical values
– falseFalsefalseFalsefalse otherwise
notEqualTo HashSetHashSetHashSetHashSetHashSet BooleanboolboolBooleanboolean trueTruetrueTruetrue if Set and argument Set differ in their values
– falseFalsefalseFalsefalse otherwise
intersection HashSetHashSetHashSetHashSetHashSet HashSetHashSetHashSetHashSetHashSet a HashSet containing those members common to both the Set and the argument Set
isDisjointFrom HashSetHashSetHashSetHashSetHashSet BooleanboolboolBooleanboolean trueTruetrueTruetrue if the Set has no items in common with the argument Set
– falseFalsefalseFalsefalse otherwise
isSubsetOf HashSetHashSetHashSetHashSetHashSet BooleanboolboolBooleanboolean trueTruetrueTruetrue if all the Set's items are also in the argument Set
– falseFalsefalseFalsefalse otherwise
isSupersetOf HashSetHashSetHashSetHashSetHashSet BooleanboolboolBooleanboolean trueTruetrueTruetrue if the Set contains all the items that are in the argument Set
– falseFalsefalseFalsefalse otherwise
length (none) IntintintIntegerint the number of members of the Set
remove value
(of HashSetHashSetHashSetHashSetHashSet members' type)		 HashSetHashSetHashSetHashSetHashSet a new Set with the argument item removed (if present)
toString (none) StringstrstringStringString a string that is a comma+space-separated ListlistListListList of the Set's members, enclosed in brackets
union HashSetHashSetHashSetHashSetHashSet HashSetHashSetHashSetHashSetHashSet a Set containing all the unique members of the Set and the argument Set (i.e. no duplicates)

Stack and Queue

Procedure method on a StackStackStackStackStack

procedure
method		 argument action
push value of StackStackStackStackStack item's type the item is added to the top of the Stack

Function dot methods on a StackStackStackStackStack

function
dot method		 argument
types		 return
types		 returns
equals StackStackStackStackStack BooleanboolboolBooleanboolean trueTruetrueTruetrue if stack and argument are identical
– falseFalsefalseFalsefalse otherwise
notEqualTo StackStackStackStackStack BooleanboolboolBooleanboolean trueTruetrueTruetrue if stack and argument differ
– falseFalsefalseFalsefalse otherwise
pop (none) StackStackStackStackStack item the item most recently pushed onto the Stack, which is now deleted from the Stack
peek (none) StackStackStackStackStack item the item most recently pushed onto the Stack (without altering the Stack)
length (none) IntintintIntegerint the number of items in the Stack
toString (none) StringstrstringStringString a String that is a comma+space-separated list of the Stack's items, enclosed in square brackets,
the last item pushed being the first in the String
withPop (none) StackStackStackStackStack the Stack with the most recently pushed item removed
withPush StackStackStackStackStack item StackStackStackStackStack the item is added to the top of the Stack and the Stack returned

Procedure method on a QueueQueueQueueQueueQueue

procedure
method		 argument action
enqueue value of QueueQueueQueueQueueQueue item's type the item is added to the tail of the queue

Function dot methods on a QueueQueueQueueQueueQueue

function
dot method		 argument
types		 return
types		 returns
equals QueueQueueQueueQueueQueue BooleanboolboolBooleanboolean trueTruetrueTruetrue if queue and argument are identical
– falseFalsefalseFalsefalse otherwise
notEqualTo QueueQueueQueueQueueQueue BooleanboolboolBooleanboolean trueTruetrueTruetrue if queue and argument differ
– falseFalsefalseFalsefalse otherwise
dequeue (none) QueueQueueQueueQueueQueue item the item least recently enqueued on the Queue, which is now deleted from the Queue
peek (none) QueueQueueQueueQueueQueue item the item least recently enqueued on the Queue (without altering the Queue)
length (none) IntintintIntegerint the number of items in the Queue
toString (none) StringstrstringStringString a String that is a comma+space-separated list of the Queue's items, enclosed in square brackets,
the first item enqueued being the first in the String
withDequeue (none) QueueQueueQueueQueueQueue the Queue with the least recently enqueued item removed
withEnqueue QueueQueueQueueQueueQueue item QueueQueueQueueQueueQueue the item is added to the tail of the Queue and the Queue returned

Examples using StackStackStackStackStack and QueueQueueQueueQueueQueue in a procedure

   ● Results of push and pop on strings in a StackStackStackStackStack that starts empty:

+procedure stackProcname?(sk as Stack<of String>parameter definitions?) 57 print(sk.length()value or expression?)58 call sk.pushprocedureName?("apple"arguments?)59 call sk.pushprocedureName?("banana"arguments?)60 call sk.pushprocedureName?("cherry"arguments?)61 print(sk.length()value or expression?)62 print(skvalue or expression?)63 print(sk.peek()value or expression?)64 print(skvalue or expression?)65 variable fruitname? set to sk.pop()value or expression?66 print(fruitvalue or expression?)67 print(skvalue or expression?)68 end procedure
+def stackProcname?(sk: Stack[str]parameter definitions?) -> None: # procedure69 print(sk.length()value or expression?)70 sk.pushprocedureName?("apple"arguments?) # procedure call71 sk.pushprocedureName?("banana"arguments?) # procedure call72 sk.pushprocedureName?("cherry"arguments?) # procedure call73 print(sk.length()value or expression?)74 print(skvalue or expression?)75 print(sk.peek()value or expression?)76 print(skvalue or expression?)77 fruitname? = sk.pop()value or expression? # variable definition78 print(fruitvalue or expression?)79 print(skvalue or expression?)80 # end procedure
+static void stackProcname?(Stack<string> skparameter definitions?) { // procedure81 Console.WriteLine(sk.length()value or expression?); // print statement82 sk.pushprocedureName?("apple"arguments?); // procedure call83 sk.pushprocedureName?("banana"arguments?); // procedure call84 sk.pushprocedureName?("cherry"arguments?); // procedure call85 Console.WriteLine(sk.length()value or expression?); // print statement86 Console.WriteLine(skvalue or expression?); // print statement87 Console.WriteLine(sk.peek()value or expression?); // print statement88 Console.WriteLine(skvalue or expression?); // print statement89 var fruitname? = sk.pop()value or expression?;90 Console.WriteLine(fruitvalue or expression?); // print statement91 Console.WriteLine(skvalue or expression?); // print statement92 } // end procedure
+Sub stackProcname?(sk As Stack(Of String)parameter definitions?) ' procedure93 Console.WriteLine(sk.length()value or expression?) ' print statement94 sk.pushprocedureName?("apple"arguments?) ' procedure call95 sk.pushprocedureName?("banana"arguments?) ' procedure call96 sk.pushprocedureName?("cherry"arguments?) ' procedure call97 Console.WriteLine(sk.length()value or expression?) ' print statement98 Console.WriteLine(skvalue or expression?) ' print statement99 Console.WriteLine(sk.peek()value or expression?) ' print statement100 Console.WriteLine(skvalue or expression?) ' print statement101 Dim fruitname? = sk.pop()value or expression? ' variable definition102 Console.WriteLine(fruitvalue or expression?) ' print statement103 Console.WriteLine(skvalue or expression?) ' print statement104 End Sub
+static void stackProcname?(Stack<String> skparameter definitions?) { // procedure105 System.out.println(sk.length()value or expression?); // print statement106 sk.pushprocedureName?("apple"arguments?); // procedure call107 sk.pushprocedureName?("banana"arguments?); // procedure call108 sk.pushprocedureName?("cherry"arguments?); // procedure call109 System.out.println(sk.length()value or expression?); // print statement110 System.out.println(skvalue or expression?); // print statement111 System.out.println(sk.peek()value or expression?); // print statement112 System.out.println(skvalue or expression?); // print statement113 var fruitname? = sk.pop()value or expression?;114 System.out.println(fruitvalue or expression?); // print statement115 System.out.println(skvalue or expression?); // print statement116 } // end procedure

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[cherry, banana, apple] — note the order of items
cherry
[cherry, banana, apple] — no change on peek

cherry
[banana, apple] — last added item was popped

   ● Results of enqueue and dequeue on strings in a QueueQueueQueueQueueQueue that starts empty:

+procedure queueProcname?(qu as Queue<of String>parameter definitions?) 117 print(qu.length()value or expression?)118 call qu.enqueueprocedureName?("apple"arguments?)119 call qu.enqueueprocedureName?("banana"arguments?)120 call qu.enqueueprocedureName?("cherry"arguments?)121 print(qu.length()value or expression?)122 print(quvalue or expression?)123 print(qu.peek()value or expression?)124 print(quvalue or expression?)125 variable fruitname? set to qu.dequeue()value or expression?126 print(fruitvalue or expression?)127 print(quvalue or expression?)128 end procedure
+def queueProcname?(qu: Queue[str]parameter definitions?) -> None: # procedure129 print(qu.length()value or expression?)130 qu.enqueueprocedureName?("apple"arguments?) # procedure call131 qu.enqueueprocedureName?("banana"arguments?) # procedure call132 qu.enqueueprocedureName?("cherry"arguments?) # procedure call133 print(qu.length()value or expression?)134 print(quvalue or expression?)135 print(qu.peek()value or expression?)136 print(quvalue or expression?)137 fruitname? = qu.dequeue()value or expression? # variable definition138 print(fruitvalue or expression?)139 print(quvalue or expression?)140 # end procedure
+static void queueProcname?(Queue<string> quparameter definitions?) { // procedure141 Console.WriteLine(qu.length()value or expression?); // print statement142 qu.enqueueprocedureName?("apple"arguments?); // procedure call143 qu.enqueueprocedureName?("banana"arguments?); // procedure call144 qu.enqueueprocedureName?("cherry"arguments?); // procedure call145 Console.WriteLine(qu.length()value or expression?); // print statement146 Console.WriteLine(quvalue or expression?); // print statement147 Console.WriteLine(qu.peek()value or expression?); // print statement148 Console.WriteLine(quvalue or expression?); // print statement149 var fruitname? = qu.dequeue()value or expression?;150 Console.WriteLine(fruitvalue or expression?); // print statement151 Console.WriteLine(quvalue or expression?); // print statement152 } // end procedure
+Sub queueProcname?(qu As Queue(Of String)parameter definitions?) ' procedure153 Console.WriteLine(qu.length()value or expression?) ' print statement154 qu.enqueueprocedureName?("apple"arguments?) ' procedure call155 qu.enqueueprocedureName?("banana"arguments?) ' procedure call156 qu.enqueueprocedureName?("cherry"arguments?) ' procedure call157 Console.WriteLine(qu.length()value or expression?) ' print statement158 Console.WriteLine(quvalue or expression?) ' print statement159 Console.WriteLine(qu.peek()value or expression?) ' print statement160 Console.WriteLine(quvalue or expression?) ' print statement161 Dim fruitname? = qu.dequeue()value or expression? ' variable definition162 Console.WriteLine(fruitvalue or expression?) ' print statement163 Console.WriteLine(quvalue or expression?) ' print statement164 End Sub
+static void queueProcname?(Queue<String> quparameter definitions?) { // procedure165 System.out.println(qu.length()value or expression?); // print statement166 qu.enqueueprocedureName?("apple"arguments?); // procedure call167 qu.enqueueprocedureName?("banana"arguments?); // procedure call168 qu.enqueueprocedureName?("cherry"arguments?); // procedure call169 System.out.println(qu.length()value or expression?); // print statement170 System.out.println(quvalue or expression?); // print statement171 System.out.println(qu.peek()value or expression?); // print statement172 System.out.println(quvalue or expression?); // print statement173 var fruitname? = qu.dequeue()value or expression?;174 System.out.println(fruitvalue or expression?); // print statement175 System.out.println(quvalue or expression?); // print statement176 } // end procedure

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0



3
[apple, banana, cherry] — note the order of items
apple
[apple, banana, cherry] — no change on peek

apple
[banana, cherry] — first added item was dequeued

Example using QueueQueueQueueQueueQueue in functions

   ● Adding to a QueueQueueQueueQueueQueue by function, then transforming its contents in a function (via a StringstrstringStringString, a ListlistListListList and the HoF reduce):

+main 1 variable quname? set to new Queue<of String>()value or expression?2 assign quvariableName? to quEnqueue(qu, "jones")value or expression?3 assign quvariableName? to quEnqueue(qu, "Smith")value or expression?4 assign quvariableName? to quEnqueue(qu, "JACKSON")value or expression?5 print(quvalue or expression?)6 print(quUpper(qu)value or expression?)7 end main +function quEnqueuename?(qu as Queue<of String>, s as Stringparameter definitions?) returns Queue<of String>Type? 8 return qu.withEnqueue(s)value or expression?9 end function +function quUppername?(qu as Queue<of String>parameter definitions?) returns Queue<of String>Type? 10 let quStringname? be qu.toString().upperCase().replace("[", "").replace("]", "")value or expression?11 let quListname? be quString.split(", ")value or expression?12 let quRname? be new Queue<of String>()value or expression?13 return quList.reduce(quR, lambda quR as Queue<of String>, s as String => quR.withEnqueue(s))value or expression?14 end function
+def main() -> None: 1 quname? = Queue[str]()value or expression? # variable definition2 quvariableName? = quEnqueue(qu, "jones")value or expression? # assignment3 quvariableName? = quEnqueue(qu, "Smith")value or expression? # assignment4 quvariableName? = quEnqueue(qu, "JACKSON")value or expression? # assignment5 print(quvalue or expression?)6 print(quUpper(qu)value or expression?)7 # end main +def quEnqueuename?(qu: Queue[str], s: strparameter definitions?) -> Queue[str]Type?: # function8 return qu.withEnqueue(s)value or expression?9 # end function +def quUppername?(qu: Queue[str]parameter definitions?) -> Queue[str]Type?: # function10 quStringname? = qu.toString().upperCase().replace("[", "").replace("]", "")value or expression? # let11 quListname? = quString.split(", ")value or expression? # let12 quRname? = Queue[str]()value or expression? # let13 return quList.reduce(quR, lambda quR: Queue[str], s: str: quR.withEnqueue(s))value or expression?14 # end function main()
+static void main() { 1 var quname? = new Queue<string>()value or expression?;2 quvariableName? = quEnqueue(qu, "jones")value or expression?; // assignment3 quvariableName? = quEnqueue(qu, "Smith")value or expression?; // assignment4 quvariableName? = quEnqueue(qu, "JACKSON")value or expression?; // assignment5 Console.WriteLine(quvalue or expression?); // print statement6 Console.WriteLine(quUpper(qu)value or expression?); // print statement7 } // end main +static Queue<string>Type? quEnqueuename?(Queue<string> qu, string sparameter definitions?) { // function8 return qu.withEnqueue(s)value or expression?;9 } // end function +static Queue<string>Type? quUppername?(Queue<string> quparameter definitions?) { // function10 var quStringname? = qu.toString().upperCase().replace("[", "").replace("]", "")value or expression?; // let11 var quListname? = quString.split(", ")value or expression?; // let12 var quRname? = new Queue<string>()value or expression?; // let13 return quList.reduce(quR, Queue<string> quR, string s => quR.withEnqueue(s))value or expression?;14 } // end function
+Sub main() 1 Dim quname? = New Queue(Of String)()value or expression? ' variable definition2 quvariableName? = quEnqueue(qu, "jones")value or expression? ' assignment3 quvariableName? = quEnqueue(qu, "Smith")value or expression? ' assignment4 quvariableName? = quEnqueue(qu, "JACKSON")value or expression? ' assignment5 Console.WriteLine(quvalue or expression?) ' print statement6 Console.WriteLine(quUpper(qu)value or expression?) ' print statement7 End Sub +Function quEnqueuename?(qu As Queue(Of String), s As Stringparameter definitions?) As Queue(Of String)Type? 8 Return qu.withEnqueue(s)value or expression?9 End Function +Function quUppername?(qu As Queue(Of String)parameter definitions?) As Queue(Of String)Type? 10 Dim quStringname? = qu.toString().upperCase().replace("(", "").replace(")", "")value or expression? ' let11 Dim quListname? = quString.split(", ")value or expression? ' let12 Dim quRname? = New Queue(Of String)()value or expression? ' let13 Return quList.reduce(quR, Function (quR As Queue(Of String), s As String) quR.withEnqueue(s))value or expression?14 End Function
public class Global {

+static void main() { 1 var quname? = new Queue<String>()value or expression?;2 quvariableName? = quEnqueue(qu, "jones")value or expression?; // assignment3 quvariableName? = quEnqueue(qu, "Smith")value or expression?; // assignment4 quvariableName? = quEnqueue(qu, "JACKSON")value or expression?; // assignment5 System.out.println(quvalue or expression?); // print statement6 System.out.println(quUpper(qu)value or expression?); // print statement7 } // end main +static Queue<String>Type? quEnqueuename?(Queue<String> qu, String sparameter definitions?) { // function8 return qu.withEnqueue(s)value or expression?;9 } // end function +static Queue<String>Type? quUppername?(Queue<String> quparameter definitions?) { // function10 var quStringname? = qu.toString().upperCase().replace("[", "").replace("]", "")value or expression?; // let11 var quListname? = quString.split(", ")value or expression?; // let12 var quRname? = new Queue<String>()value or expression?; // let13 return quList.reduce(quR, (Queue<String> quR, String s) -> quR.withEnqueue(s))value or expression?;14 } // end function
} // end Global




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[jones, Smith, JACKSON]
[JONES, SMITH, JACKSON]

Tuple

A Tuple is not a value or data structure type. Rather, it is a small collection of values of differing types held together and referenced by a single identifier.

It may be considered a lightweight alternative to defining a class for some specific purpose.

The items in a Tuple may be literal or named values.

Tuples are referred to as 2-tuples, 3-tuples, etc. according to the number of values they hold.

An item within a Tuple may be another Tuple, giving nested Tuples.

A function may return a Tuple.

A Tuple differs from a ListlistListListList in that:

Common uses include:

Defining a Tuple

A new Tuple is defined by a list of items separated by commas and enclosed in round brackets:

variable pointname? set to (3, 4)value or expression?31pointname? = (3, 4)value or expression? # variable definition32var pointname? = (3, 4)value or expression?;33Dim pointname? = (3, 4)value or expression? ' variable definition34var pointname? = (3, 4)value or expression?;35 variable tname? set to (3, "apple", true)value or expression?36tname? = (3, "apple", True)value or expression? # variable definition37var tname? = (3, "apple", true)value or expression?;38Dim tname? = (3, "apple", True)value or expression? ' variable definition39var tname? = (3, "apple", true)value or expression?;40

Accessing items in a Tuple

The items in a Tuple may be individually addressed by a dot reference and the special properties item_item_item_item_item_N, thus:

+main 15 variable tname? set to (3, "apple", true)value or expression?16 print(tvalue or expression?)17 print(t.item_0value or expression?)18 print(t.item_1value or expression?)19 print(t.item_2value or expression?)20 end main
+def main() -> None: 21 tname? = (3, "apple", True)value or expression? # variable definition22 print(tvalue or expression?)23 print(t.item_0value or expression?)24 print(t.item_1value or expression?)25 print(t.item_2value or expression?)26 # end main
+static void main() { 27 var tname? = (3, "apple", true)value or expression?;28 Console.WriteLine(tvalue or expression?); // print statement29 Console.WriteLine(t.item_0value or expression?); // print statement30 Console.WriteLine(t.item_1value or expression?); // print statement31 Console.WriteLine(t.item_2value or expression?); // print statement32 } // end main
+Sub main() 33 Dim tname? = (3, "apple", True)value or expression? ' variable definition34 Console.WriteLine(tvalue or expression?) ' print statement35 Console.WriteLine(t.item_0value or expression?) ' print statement36 Console.WriteLine(t.item_1value or expression?) ' print statement37 Console.WriteLine(t.item_2value or expression?) ' print statement38 End Sub
+static void main() { 39 var tname? = (3, "apple", true)value or expression?;40 System.out.println(tvalue or expression?); // print statement41 System.out.println(t.item_0value or expression?); // print statement42 System.out.println(t.item_1value or expression?); // print statement43 System.out.println(t.item_2value or expression?); // print statement44 } // end main


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(3, apple, true)
3
apple
true

And where p1 and p2 represent points each with 2-tuples containing two FloatfloatdoubleDoubledouble values, this function returns the distance between them:

+function distanceBetweenname?(p1 as (Float, Float), p2 as (Float, Float)parameter definitions?) returns FloatType? 45 return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?46 end function
+def distanceBetweenname?(p1: tuple[float, float], p2: tuple[float, float]parameter definitions?) -> floatType?: # function47 return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?48 # end function
+static doubleType? distanceBetweenname?((double, double) p1, (double, double) p2parameter definitions?) { // function49 return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?;50 } // end function
+Function distanceBetweenname?(p1 As (Double, Double), p2 As (Double, Double)parameter definitions?) As DoubleType? 51 Return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?52 End Function
+static doubleType? distanceBetweenname?((double, double) p1, (double, double) p2parameter definitions?) { // function53 return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?;54 } // end function

Note that the appropriate item_item_item_item_item_Ns will be listed in the Editor's drop-down menu options for the referenced Tuple.

Function dot methods on a Tuple

function
dot methods		 argument
types		 return
type		 returns
equals Tuple BooleanboolboolBooleanboolean trueTruetrueTruetrue if the types, item values and order all equal those of the argument,
– falseFalsefalseFalsefalse otherwise
notEqualTo Tuple BooleanboolboolBooleanboolean trueTruetrueTruetrue if any of the types, item values and order differ from those of the argument,
– falseFalsefalseFalsefalse otherwise
toString (none) StringstrstringStringString String containing Tuple's items surrounded by brackets

Graphic types

Block graphics

Block graphics provides a simple way to create low resolution graphics, ideal for simple but engaging games for example.

The graphics are defined and displayed on a grid that is 40 blocks wide by 30 blocks high.

Each block is be rendered as a solid colour.

An example of block graphics to produce a rapidly changing pattern of coloured blocks:

+main 55 variable gridname? set to createBlockGraphics(white)value or expression?56 +while truecondition? 57 variable xname? set to randint(0, 39)value or expression?58 variable yname? set to randint(0, 29)value or expression?59 variable colourname? set to randint(0, white - 1)value or expression?60 assign grid[x][y]variableName? to colourvalue or expression?61 call displayBlocksprocedureName?(gridarguments?)62 end while end main
+def main() -> None: 63 gridname? = createBlockGraphics(white)value or expression? # variable definition64 +while Truecondition?: 65 xname? = randint(0, 39)value or expression? # variable definition66 yname? = randint(0, 29)value or expression? # variable definition67 colourname? = randint(0, white - 1)value or expression? # variable definition68 grid[x][y]variableName? = colourvalue or expression? # assignment69 displayBlocksprocedureName?(gridarguments?) # procedure call70 # end while # end main
+static void main() { 71 var gridname? = createBlockGraphics(white)value or expression?;72 +while (truecondition?) { 73 var xname? = randint(0, 39)value or expression?;74 var yname? = randint(0, 29)value or expression?;75 var colourname? = randint(0, white - 1)value or expression?;76 grid[x][y]variableName? = colourvalue or expression?; // assignment77 displayBlocksprocedureName?(gridarguments?); // procedure call78 } // end while } // end main
+Sub main() 79 Dim gridname? = createBlockGraphics(white)value or expression? ' variable definition80 +While Truecondition? 81 Dim xname? = randint(0, 39)value or expression? ' variable definition82 Dim yname? = randint(0, 29)value or expression? ' variable definition83 Dim colourname? = randint(0, white - 1)value or expression? ' variable definition84 grid(x)(y)variableName? = colourvalue or expression? ' assignment85 displayBlocksprocedureName?(gridarguments?) ' procedure call86 End While End Sub
+static void main() { 87 var gridname? = createBlockGraphics(white)value or expression?;88 +while (truecondition?) { 89 var xname? = randint(0, 39)value or expression?;90 var yname? = randint(0, 29)value or expression?;91 var colourname? = randint(0, white - 1)value or expression?;92 grid[x][y]variableName? = colourvalue or expression?; // assignment93 displayBlocksprocedureName?(gridarguments?); // procedure call94 } // end while } // end main

Notes

Turtle graphics

Turtle graphics are implemented with output to the IDE's display pane, i.e. the 'paper' on which the turtle draws.

The area is 200 turtle units wide by 150 turtle units high, and both integer and floating point values of turtle units can be used. If a turtle is placed or moved outside the 200 × 150 area boundary, it will not cause an error, but the turtle and any lines drawn outside the boundary will not be visible.

The origin for turtle units (0,0) is at the centre of the area: positive x rightwards, positive y upwards. So the top left corner of the display is at (-100,75).

A new turtle's default starting position is at (0,0) facing upwards (headingheadingheadingheadingheading is 0), from where a move will be in the y direction.

You can move and turn a turtle, causing lines to be drawn, whether or not the turtle is showing.

Procedure methods on a Turtle

procedure
method		 argument
types		 action
clearAndReset (none) clears the turtle display and moves the turtle to its starting position and heading
hide (none) makes the turtle invisible in the display
move IntintintIntegerint or FloatfloatdoubleDoubledouble moves the turtle the specified number of turtle units in the direction of its heading or,
if negative, in the opposite direction
moveTo IntintintIntegerint or FloatfloatdoubleDoubledouble,
IntintintIntegerint or FloatfloatdoubleDoubledouble		 moves the turtle to the specified x,y position, drawing its path if its pen is down
penColour IntintintIntegerint changes the colour of its path in the display to the literal or named value specified
penDown (none) makes the turtle's subsequent moves leave a trace of its path in the display
penUp (none) makes the turtle's subsequent moves leave no trace of its path in the display
penWidth IntintintIntegerint or FloatfloatdoubleDoubledouble changes the width of the line tracing the turtle's path in the display
default (and minimum) is 1
placeAt IntintintIntegerint or FloatfloatdoubleDoubledouble,
IntintintIntegerint or FloatfloatdoubleDoubledouble		 places or repositions the turtle at the x,y position specified without drawing a path
show (none) makes the turtle visible in the display as a green blob
marked with a black radius that indicates its heading
turn IntintintIntegerint or FloatfloatdoubleDoubledouble turns the turtle through the specified number of degrees clockwise or,
if negative, anticlockwise
turnToHeading IntintintIntegerint or FloatfloatdoubleDoubledouble turns the turtle to face in the direction specified in degrees
where 0 is upward and increasing values go clockwise from there

Properties of a Turtle

The current location and heading of the turtle may be read using the properties xxxxx, yyyyy, and headingheadingheadingheadingheading.

Property
name type description default
headingheadingheadingheadingheading FloatfloatdoubleDoubledouble the direction in which the turtle is pointing
in degrees clockwise from North		 0.0 degrees,
i.e. upward in the display
xxxxx, yyyyy FloatfloatdoubleDoubledouble, FloatfloatdoubleDoubledouble the x,y coordinates of the turtle's current position 0.0, 0.0

Examples using turtle graphics

   ● To draw a square:

+main 95 variable tname? set to new Turtle()value or expression?96 call t.placeAtprocedureName?(-75, 50arguments?)97 call t.showprocedureName?(arguments?)98 +for iitem? in range(1, 5)source? 99 call t.turnprocedureName?(90arguments?)100 call t.moveprocedureName?(80arguments?)101 call sleepprocedureName?(0.5arguments?)102 end for end main
+def main() -> None: 103 tname? = Turtle()value or expression? # variable definition104 t.placeAtprocedureName?(-75, 50arguments?) # procedure call105 t.showprocedureName?(arguments?) # procedure call106 +for iitem? in range(1, 5)source?: 107 t.turnprocedureName?(90arguments?) # procedure call108 t.moveprocedureName?(80arguments?) # procedure call109 sleepprocedureName?(0.5arguments?) # procedure call110 # end for # end main
+static void main() { 111 var tname? = new Turtle()value or expression?;112 t.placeAtprocedureName?(-75, 50arguments?); // procedure call113 t.showprocedureName?(arguments?); // procedure call114 +foreach (var iitem? in range(1, 5)source?) { 115 t.turnprocedureName?(90arguments?); // procedure call116 t.moveprocedureName?(80arguments?); // procedure call117 sleepprocedureName?(0.5arguments?); // procedure call118 } // end foreach } // end main
+Sub main() 119 Dim tname? = New Turtle()value or expression? ' variable definition120 t.placeAtprocedureName?(-75, 50arguments?) ' procedure call121 t.showprocedureName?(arguments?) ' procedure call122 +For Each iitem? In range(1, 5)source? 123 t.turnprocedureName?(90arguments?) ' procedure call124 t.moveprocedureName?(80arguments?) ' procedure call125 sleepprocedureName?(0.5arguments?) ' procedure call126 Next i End Sub
+static void main() { 127 var tname? = new Turtle()value or expression?;128 t.placeAtprocedureName?(-75, 50arguments?); // procedure call129 t.showprocedureName?(arguments?); // procedure call130 +foreach (var iitem? in range(1, 5)source?) { 131 t.turnprocedureName?(90arguments?); // procedure call132 t.moveprocedureName?(80arguments?); // procedure call133 sleepprocedureName?(0.5arguments?); // procedure call134 } // end foreach } // end main

Turtle square

   ● To draw a fractal snowflake, using a procedure and recursion:

+main 1 variable tname? set to new Turtle()value or expression?2 call t.placeAtprocedureName?(-50, 30arguments?)3 call t.turnprocedureName?(90arguments?)4 call t.showprocedureName?(arguments?)5 +for iitem? in range(1, 4)source? 6 call drawSideprocedureName?(side, targuments?)7 call t.turnprocedureName?(120arguments?)8 end for end main +constant sidename? set to 100literal value or data structure?9 +procedure drawSidename?(length as Float, t as Turtleparameter definitions?) 10 +if (length > 1)condition? then 11 variable thirdname? set to length/3value or expression?12 call drawSideprocedureName?(third, targuments?)13 call t.turnprocedureName?(-60arguments?)14 call drawSideprocedureName?(third, targuments?)15 call t.turnprocedureName?(120arguments?)16 call drawSideprocedureName?(third, targuments?)17 call t.turnprocedureName?(-60arguments?)18 call drawSideprocedureName?(third, targuments?)19 else20 call t.moveprocedureName?(lengtharguments?)21 end if end procedure
+def main() -> None: 1 tname? = Turtle()value or expression? # variable definition2 t.placeAtprocedureName?(-50, 30arguments?) # procedure call3 t.turnprocedureName?(90arguments?) # procedure call4 t.showprocedureName?(arguments?) # procedure call5 +for iitem? in range(1, 4)source?: 6 drawSideprocedureName?(side, targuments?) # procedure call7 t.turnprocedureName?(120arguments?) # procedure call8 # end for # end main +sidename? = 100literal value or data structure? # constant9 +def drawSidename?(length: float, t: Turtleparameter definitions?) -> None: # procedure10 +if (length > 1)condition?: 11 thirdname? = length/3value or expression? # variable definition12 drawSideprocedureName?(third, targuments?) # procedure call13 t.turnprocedureName?(-60arguments?) # procedure call14 drawSideprocedureName?(third, targuments?) # procedure call15 t.turnprocedureName?(120arguments?) # procedure call16 drawSideprocedureName?(third, targuments?) # procedure call17 t.turnprocedureName?(-60arguments?) # procedure call18 drawSideprocedureName?(third, targuments?) # procedure call19 else:20 t.moveprocedureName?(lengtharguments?) # procedure call21 # end if # end procedure main()
+static void main() { 1 var tname? = new Turtle()value or expression?;2 t.placeAtprocedureName?(-50, 30arguments?); // procedure call3 t.turnprocedureName?(90arguments?); // procedure call4 t.showprocedureName?(arguments?); // procedure call5 +foreach (var iitem? in range(1, 4)source?) { 6 drawSideprocedureName?(side, targuments?); // procedure call7 t.turnprocedureName?(120arguments?); // procedure call8 } // end foreach } // end main +const Int sidename? = 100literal value or data structure?;9 +static void drawSidename?(double length, Turtle tparameter definitions?) { // procedure10 +if ((length > 1)condition?) { 11 var thirdname? = length/3value or expression?;12 drawSideprocedureName?(third, targuments?); // procedure call13 t.turnprocedureName?(-60arguments?); // procedure call14 drawSideprocedureName?(third, targuments?); // procedure call15 t.turnprocedureName?(120arguments?); // procedure call16 drawSideprocedureName?(third, targuments?); // procedure call17 t.turnprocedureName?(-60arguments?); // procedure call18 drawSideprocedureName?(third, targuments?); // procedure call19 } else {20 t.moveprocedureName?(lengtharguments?); // procedure call21 } // end if } // end procedure
+Sub main() 1 Dim tname? = New Turtle()value or expression? ' variable definition2 t.placeAtprocedureName?(-50, 30arguments?) ' procedure call3 t.turnprocedureName?(90arguments?) ' procedure call4 t.showprocedureName?(arguments?) ' procedure call5 +For Each iitem? In range(1, 4)source? 6 drawSideprocedureName?(side, targuments?) ' procedure call7 t.turnprocedureName?(120arguments?) ' procedure call8 Next i End Sub +Const sidename? = 100literal value or data structure?9 +Sub drawSidename?(length As Double, t As Turtleparameter definitions?) ' procedure10 +If (length > 1)condition? Then 11 Dim thirdname? = length/3value or expression? ' variable definition12 drawSideprocedureName?(third, targuments?) ' procedure call13 t.turnprocedureName?(-60arguments?) ' procedure call14 drawSideprocedureName?(third, targuments?) ' procedure call15 t.turnprocedureName?(120arguments?) ' procedure call16 drawSideprocedureName?(third, targuments?) ' procedure call17 t.turnprocedureName?(-60arguments?) ' procedure call18 drawSideprocedureName?(third, targuments?) ' procedure call19 Else20 t.moveprocedureName?(lengtharguments?) ' procedure call21 End If End Sub
public class Global {

+static void main() { 1 var tname? = new Turtle()value or expression?;2 t.placeAtprocedureName?(-50, 30arguments?); // procedure call3 t.turnprocedureName?(90arguments?); // procedure call4 t.showprocedureName?(arguments?); // procedure call5 +foreach (var iitem? in range(1, 4)source?) { 6 drawSideprocedureName?(side, targuments?); // procedure call7 t.turnprocedureName?(120arguments?); // procedure call8 } // end foreach } // end main +static final Int sidename? = 100literal value or data structure?; // constant9 +static void drawSidename?(double length, Turtle tparameter definitions?) { // procedure10 +if ((length > 1)condition?) { 11 var thirdname? = length/3value or expression?;12 drawSideprocedureName?(third, targuments?); // procedure call13 t.turnprocedureName?(-60arguments?); // procedure call14 drawSideprocedureName?(third, targuments?); // procedure call15 t.turnprocedureName?(120arguments?); // procedure call16 drawSideprocedureName?(third, targuments?); // procedure call17 t.turnprocedureName?(-60arguments?); // procedure call18 drawSideprocedureName?(third, targuments?); // procedure call19 } else {20 t.moveprocedureName?(lengtharguments?); // procedure call21 } // end if } // end procedure
} // end Global

Turtle snowflake

Vector graphics

Vector graphics are implemented using the SVG (Scalable Vector Graphics) Html tag <svg>, and are output to the display pane in the user interface.

The area is 100 units wide by 75 units high, and both integer and floating point values of the units can be used.

The origin of the units (0,0) is at the top left corner of the display: positive x rightwards, positive y downwards. So for example the centre of the display is at (50, 37.5).

The names of the shapes broadly correspond to the names of SVG tags:

The properties of these shapes are named to reflect the attributes used in the SVG tags but some names differ. For example, SVG's stroke-width is assigned with property strokeWidthstrokeWidthstrokeWidthstrokeWidthstrokeWidth, to make it a valid identifier . Also strokestrokestrokestrokestroke and fillfillfillfillfill are set by the properties strokeColourstrokeColourstrokeColourstrokeColourstrokeColour and fillColourfillColourfillColourfillColourfillColour.

In addition, graphics may be displayed from any valid string of SVG tags, as described in RawVGRawVGRawVGRawVGRawVG .

Defining Vector graphic shapes

A set of SVG shapes is defined in either a List<of VectorGraphic>list[VectorGraphic]List<VectorGraphic>List(Of VectorGraphic)List<VectorGraphic> or a ListlistListListList of any specific type of VectorGraphicVectorGraphicVectorGraphicVectorGraphicVectorGraphic (e.g. List<of CircleVG>list[CircleVG]List<CircleVG>List(Of CircleVG)List<CircleVG>) by using the ListlistListListList append method.

createVectorGraphics is a convenience method that returns an empty List<of VectorGraphic>list[VectorGraphic]List<VectorGraphic>List(Of VectorGraphic)List<VectorGraphic>

VectorGraphicVectorGraphicVectorGraphicVectorGraphicVectorGraphic is the abstract superclass of all ..VG shapes. You use it when you want to define a ListlistListListList holding different types of shape.

Adding a shape returns a new instance of the ListlistListListList which must be assigned to a new or existing variable.

The constructors for the VG types require arguments defining the attributes of the relevant SVG tags, so defaults are supplied from the class properties, as shown in the table below.

To change the value of property 'p..', call the setP.. procedure method on the vector graphic or, in a function, use the withP.. dot method on the vector graphic, in either case specifying new values in the arguments.

The fillColourfillColourfillColourfillColourfillColour and strokeColourstrokeColourstrokeColourstrokeColourstrokeColour properties may be specified as described under Colours . Only fillColourfillColourfillColourfillColourfillColour can be specified as transparenttransparenttransparenttransparenttransparent.

Note that the heightheightheightheightheight and widthwidthwidthwidthwidth properties of an image are also dependent on the dimensions of the original graphic file.

Displaying Vector graphic shapes

As with Block graphics, the assembled ListlistListListList of shapes is not displayed until call procedure displayVectorGraphics with the ListlistListListList as its argument, thus allowing you to make multiple changes before display.

And as with using SVG in Html, the shapes are drawn in the order in which they are added to the VectorGraphicVectorGraphicVectorGraphicVectorGraphicVectorGraphic instance. Later shapes are positioned in front of earlier ones.

Function dot methods on Vector graphic shapes

function
dot method		 on
type		 argument
types		 return
type		 returns
asHtml ImageVGImageVGImageVGImageVGImageVG none StringstrstringStringString string containing the Html <img> tag filled with the image's URL and attribute values
asSVG CircleVGCircleVGCircleVGCircleVGCircleVG none StringstrstringStringString string containing the SVG <circle> tag filled with the circle's attribute values
asSVG ImageVGImageVGImageVGImageVGImageVG none StringstrstringStringString string containing the SVG <image> tag filled with the image's URL and attribute values
asSVG LineVGLineVGLineVGLineVGLineVG none StringstrstringStringString string containing the SVG <line> tag filled with the line's attribute values
asSVG RectangleVGRectangleVGRectangleVGRectangleVGRectangleVG none StringstrstringStringString string containing the SVG <rectangle> tag filled with the rectangle's attribute values

Properties of Vector graphic shapes

This table lists the properties of the Vector graphic shapes and their default values, together with the procedure and function methods provided to alter their values in a given instance.

Property Vector graphic shape Property Method
name type CircleVG ImageVG LineVG RectangleVG description default procedure function
altaltaltaltalt StringstrstringStringString ✔ alternate textual description (for accessibility) empty string setAlt withAlt
centreXcentreXcentreXcentreXcentreX FloatfloatdoubleDoubledouble ✔ horizontal position of circle centre 50 setCentreX withCentreX
centreYcentreYcentreYcentreYcentreY FloatfloatdoubleDoubledouble ✔ vertical position of circle centre 37.5 setCentreY withCentreY
fillColourfillColourfillColourfillColourfillColour IntintintIntegerint ✔ ✔ colour to fill the shape yellowyellowyellowyellowyellow setFillColour withFillColour
heightheightheightheightheight FloatfloatdoubleDoubledouble ✔ ✔ height to render the shape or the image Image: 13.2
Rectangle: 20		 setHeight withHeight
radiusradiusradiusradiusradius FloatfloatdoubleDoubledouble ✔ radius of circle 10 setRadius withRadius
strokeColourstrokeColourstrokeColourstrokeColourstrokeColour IntintintIntegerint ✔ ✔ ✔ colour of the strokes in the shape blackblackblackblackblack setStrokeColour withStrokeColour
strokeWidthstrokeWidthstrokeWidthstrokeWidthstrokeWidth IntintintIntegerint ✔ ✔ ✔ width of the strokes in the shape 1 setStrokeWidth withStrokeWidth
titletitletitletitletitle FloatfloatdoubleDoubledouble ✔ title text empty string setTitle withTitle
widthwidthwidthwidthwidth FloatfloatdoubleDoubledouble ✔ ✔ width to render the shape or the image Image: 13.2
Rectangle: 40		 setWidth withWidth
xxxxx, yyyyy FloatfloatdoubleDoubledouble, FloatfloatdoubleDoubledouble ✔ ✔ ✔ ✔ image's x,y position from top left Image: 0, 0
Rectangle: 10, 10		 setX, setY withX, withY
x1x1x1x1x1, y1y1y1y1y1 FloatfloatdoubleDoubledouble, FloatfloatdoubleDoubledouble ✔ ✔ line's starting x,y position from top left 10, 10 setX1, setY1 withX1, withY1
x2x2x2x2x2, y2y2y2y2y2 FloatfloatdoubleDoubledouble, FloatfloatdoubleDoubledouble ✔ ✔ line's ending x,y position from top left 70, 40 setX2, setY2 withX2, withY2

Examples using simple vector graphics

   ● To draw a circle with a coloured circumference:

+main 22 variable vgname? set to createVectorGraphics()value or expression?23 variable circname? set to new CircleVG()value or expression?24 call circ.setCentreXprocedureName?(20arguments?)25 call circ.setCentreYprocedureName?(20arguments?)26 call circ.setRadiusprocedureName?(5arguments?)27 call circ.setFillColourprocedureName?(greenarguments?)28 call circ.setStrokeColourprocedureName?(redarguments?)29 call circ.setStrokeWidthprocedureName?(2arguments?)30 call vg.appendprocedureName?(circarguments?)31 call displayVectorGraphicsprocedureName?(vgarguments?)32 end main
+def main() -> None: 33 vgname? = createVectorGraphics()value or expression? # variable definition34 circname? = CircleVG()value or expression? # variable definition35 circ.setCentreXprocedureName?(20arguments?) # procedure call36 circ.setCentreYprocedureName?(20arguments?) # procedure call37 circ.setRadiusprocedureName?(5arguments?) # procedure call38 circ.setFillColourprocedureName?(greenarguments?) # procedure call39 circ.setStrokeColourprocedureName?(redarguments?) # procedure call40 circ.setStrokeWidthprocedureName?(2arguments?) # procedure call41 vg.appendprocedureName?(circarguments?) # procedure call42 displayVectorGraphicsprocedureName?(vgarguments?) # procedure call43 # end main
+static void main() { 44 var vgname? = createVectorGraphics()value or expression?;45 var circname? = new CircleVG()value or expression?;46 circ.setCentreXprocedureName?(20arguments?); // procedure call47 circ.setCentreYprocedureName?(20arguments?); // procedure call48 circ.setRadiusprocedureName?(5arguments?); // procedure call49 circ.setFillColourprocedureName?(greenarguments?); // procedure call50 circ.setStrokeColourprocedureName?(redarguments?); // procedure call51 circ.setStrokeWidthprocedureName?(2arguments?); // procedure call52 vg.appendprocedureName?(circarguments?); // procedure call53 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call54 } // end main
+Sub main() 55 Dim vgname? = createVectorGraphics()value or expression? ' variable definition56 Dim circname? = New CircleVG()value or expression? ' variable definition57 circ.setCentreXprocedureName?(20arguments?) ' procedure call58 circ.setCentreYprocedureName?(20arguments?) ' procedure call59 circ.setRadiusprocedureName?(5arguments?) ' procedure call60 circ.setFillColourprocedureName?(greenarguments?) ' procedure call61 circ.setStrokeColourprocedureName?(redarguments?) ' procedure call62 circ.setStrokeWidthprocedureName?(2arguments?) ' procedure call63 vg.appendprocedureName?(circarguments?) ' procedure call64 displayVectorGraphicsprocedureName?(vgarguments?) ' procedure call65 End Sub
+static void main() { 66 var vgname? = createVectorGraphics()value or expression?;67 var circname? = new CircleVG()value or expression?;68 circ.setCentreXprocedureName?(20arguments?); // procedure call69 circ.setCentreYprocedureName?(20arguments?); // procedure call70 circ.setRadiusprocedureName?(5arguments?); // procedure call71 circ.setFillColourprocedureName?(greenarguments?); // procedure call72 circ.setStrokeColourprocedureName?(redarguments?); // procedure call73 circ.setStrokeWidthprocedureName?(2arguments?); // procedure call74 vg.appendprocedureName?(circarguments?); // procedure call75 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call76 } // end main

circle

   ● To draw a circle that changes between red and green every second:

+main 77 variable vgname? set to new List<of VectorGraphic>()value or expression?78 variable circname? set to new CircleVG()value or expression?79 call circ.setCentreXprocedureName?(50arguments?)80 call circ.setCentreYprocedureName?(37.5arguments?)81 call circ.setRadiusprocedureName?(30arguments?)82 call circ.setFillColourprocedureName?(greenarguments?)83 call vg.appendprocedureName?(circarguments?)84 +while truecondition? 85 call displayVectorGraphicsprocedureName?(vgarguments?)86 call sleepprocedureName?(1arguments?)87 call circ.setFillColourprocedureName?(redarguments?)88 call displayVectorGraphicsprocedureName?(vgarguments?)89 call sleepprocedureName?(1arguments?)90 call circ.setFillColourprocedureName?(greenarguments?)91 end while call displayVectorGraphicsprocedureName?(vgarguments?)92 end main
+def main() -> None: 93 vgname? = list[VectorGraphic]()value or expression? # variable definition94 circname? = CircleVG()value or expression? # variable definition95 circ.setCentreXprocedureName?(50arguments?) # procedure call96 circ.setCentreYprocedureName?(37.5arguments?) # procedure call97 circ.setRadiusprocedureName?(30arguments?) # procedure call98 circ.setFillColourprocedureName?(greenarguments?) # procedure call99 vg.appendprocedureName?(circarguments?) # procedure call100 +while Truecondition?: 101 displayVectorGraphicsprocedureName?(vgarguments?) # procedure call102 sleepprocedureName?(1arguments?) # procedure call103 circ.setFillColourprocedureName?(redarguments?) # procedure call104 displayVectorGraphicsprocedureName?(vgarguments?) # procedure call105 sleepprocedureName?(1arguments?) # procedure call106 circ.setFillColourprocedureName?(greenarguments?) # procedure call107 # end while displayVectorGraphicsprocedureName?(vgarguments?) # procedure call108 # end main
+static void main() { 109 var vgname? = new List<VectorGraphic>()value or expression?;110 var circname? = new CircleVG()value or expression?;111 circ.setCentreXprocedureName?(50arguments?); // procedure call112 circ.setCentreYprocedureName?(37.5arguments?); // procedure call113 circ.setRadiusprocedureName?(30arguments?); // procedure call114 circ.setFillColourprocedureName?(greenarguments?); // procedure call115 vg.appendprocedureName?(circarguments?); // procedure call116 +while (truecondition?) { 117 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call118 sleepprocedureName?(1arguments?); // procedure call119 circ.setFillColourprocedureName?(redarguments?); // procedure call120 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call121 sleepprocedureName?(1arguments?); // procedure call122 circ.setFillColourprocedureName?(greenarguments?); // procedure call123 } // end while displayVectorGraphicsprocedureName?(vgarguments?); // procedure call124 } // end main
+Sub main() 125 Dim vgname? = New List(Of VectorGraphic)()value or expression? ' variable definition126 Dim circname? = New CircleVG()value or expression? ' variable definition127 circ.setCentreXprocedureName?(50arguments?) ' procedure call128 circ.setCentreYprocedureName?(37.5arguments?) ' procedure call129 circ.setRadiusprocedureName?(30arguments?) ' procedure call130 circ.setFillColourprocedureName?(greenarguments?) ' procedure call131 vg.appendprocedureName?(circarguments?) ' procedure call132 +While Truecondition? 133 displayVectorGraphicsprocedureName?(vgarguments?) ' procedure call134 sleepprocedureName?(1arguments?) ' procedure call135 circ.setFillColourprocedureName?(redarguments?) ' procedure call136 displayVectorGraphicsprocedureName?(vgarguments?) ' procedure call137 sleepprocedureName?(1arguments?) ' procedure call138 circ.setFillColourprocedureName?(greenarguments?) ' procedure call139 End While displayVectorGraphicsprocedureName?(vgarguments?) ' procedure call140 End Sub
+static void main() { 141 var vgname? = new List<VectorGraphic>()value or expression?;142 var circname? = new CircleVG()value or expression?;143 circ.setCentreXprocedureName?(50arguments?); // procedure call144 circ.setCentreYprocedureName?(37.5arguments?); // procedure call145 circ.setRadiusprocedureName?(30arguments?); // procedure call146 circ.setFillColourprocedureName?(greenarguments?); // procedure call147 vg.appendprocedureName?(circarguments?); // procedure call148 +while (truecondition?) { 149 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call150 sleepprocedureName?(1arguments?); // procedure call151 circ.setFillColourprocedureName?(redarguments?); // procedure call152 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call153 sleepprocedureName?(1arguments?); // procedure call154 circ.setFillColourprocedureName?(greenarguments?); // procedure call155 } // end while displayVectorGraphicsprocedureName?(vgarguments?); // procedure call156 } // end main

RawVGRawVGRawVGRawVGRawVG

Strings containing raw SVG tags may be assembled and plotted directly using class RawVGRawVGRawVGRawVGRawVG. By this means features such as simple SVG animation can be defined.

Example using RawVGRawVGRawVGRawVGRawVG

   ● To display a repeating movement of a circle:

+main 157 variable movingCirclename? set to "<circle cx='50' cy='50' r='50' style='fill:red;'>\n<animate attributeName='cx' begin='0s' dur='2s' from='50' to='90%' repeatCount='indefinite' /></circle>"value or expression?158 variable rawname? set to (new RawVG()).withContent(movingCircle)value or expression?159 call displayVectorGraphicsprocedureName?([raw]arguments?)160 end main
+def main() -> None: 161 movingCirclename? = "<circle cx='50' cy='50' r='50' style='fill:red;'>\n<animate attributeName='cx' begin='0s' dur='2s' from='50' to='90%' repeatCount='indefinite' /></circle>"value or expression? # variable definition162 rawname? = (RawVG()).withContent(movingCircle)value or expression? # variable definition163 displayVectorGraphicsprocedureName?([raw]arguments?) # procedure call164 # end main
+static void main() { 165 var movingCirclename? = "<circle cx='50' cy='50' r='50' style='fill:red;'>\n<animate attributeName='cx' begin='0s' dur='2s' from='50' to='90%' repeatCount='indefinite' /></circle>"value or expression?;166 var rawname? = (new RawVG()).withContent(movingCircle)value or expression?;167 displayVectorGraphicsprocedureName?(new [] {raw}arguments?); // procedure call168 } // end main
+Sub main() 169 Dim movingCirclename? = "<circle cx='50' cy='50' r='50' style='fill:red;'>\n<animate attributeName='cx' begin='0s' dur='2s' from='50' to='90%' repeatCount='indefinite' /></circle>"value or expression? ' variable definition170 Dim rawname? = (New RawVG()).withContent(movingCircle)value or expression? ' variable definition171 displayVectorGraphicsprocedureName?({raw}arguments?) ' procedure call172 End Sub
+static void main() { 173 var movingCirclename? = "<circle cx='50' cy='50' r='50' style='fill:red;'>\n<animate attributeName='cx' begin='0s' dur='2s' from='50' to='90%' repeatCount='indefinite' /></circle>"value or expression?;174 var rawname? = (new RawVG()).withContent(movingCircle)value or expression?;175 displayVectorGraphicsprocedureName?(list(raw)arguments?); // procedure call176 } // end main

Combining graphic outputs

Program outputs, whether text or graphical, can be combined in the display. In particular, Block graphics and text or Html printing can share the display along with either Vector graphics or Turtle graphics (but not both).

If you want to share the display in this way, remember that both text and Html print outputs appear sequentially down the display (which can be scrolled), whereas the graphic outputs are positioned in the display using their own absolute coordinate systems.

The order in which the outputs are displayed (and therefore overwrite) is:

  1. Block graphics
  2. Vector or Turtle graphics
  3. Printed text or Html

So some care is needed to manage the layout in the display.

Note that, while vector graphics are being drawn, printed text that exceeds the height of the display does not scroll until the graphic completes.

Other types

Random

Generating random numbers within a function

It is not possible to use the system methods random or randint within a function because they create unseen side effects. You may use those system methods outside the function and pass the resulting random number (as an IntintintIntegerint or a FloatfloatdoubleDoubledouble) as an argument into a function.

It is, however, possible to create and use random numbers within a function, but it requires a different approach and is a little more complex. You use the special type RandomRandomRandomRandomRandom. (Note the upper case R required for a type name).

You start by getting a seed random number in your main routine or in a procedure using method initialiseFromClock:

variable rndname? set to new Random()value or expression?41rndname? = Random()value or expression? # variable definition42var rndname? = new Random()value or expression?;43Dim rndname? = New Random()value or expression? ' variable definition44var rndname? = new Random()value or expression?;45
call rnd.initialiseFromClockprocedureName?(arguments?)46rnd.initialiseFromClockprocedureName?(arguments?) # procedure call47rnd.initialiseFromClockprocedureName?(arguments?); // procedure call48rnd.initialiseFromClockprocedureName?(arguments?) ' procedure call49rnd.initialiseFromClockprocedureName?(arguments?); // procedure call50

Then, in a function, apply dot method asFloat or asInt as appropriate to the RandomRandomRandomRandomRandom passed in, and dot method nextGen to obtain a new instance of RandomRandomRandomRandomRandom for generating the next random number.

Avoid applying nextGen more than once on the same RandomRandomRandomRandomRandom instance, because it will return the same values.

If the initialiseFromClock call is absent, the program will still generate a sequence of random values, but the sequence will be exactly the same each time you run the program. Initialising from the clock ensures that you get a different sequence each run. Using RandomRandomRandomRandomRandom without so initialising, however, can be extremely useful for testing purposes since the results are repeatable.

Function method for random seed

procedure
method		 argument
type		 action
initialiseFromClock (none) uses the system clock to provide a seed
from which to generate fresh random values

Function dot methods on a RandomRandomRandomRandomRandom

function
dot method		 argument
types		 return
type		 returns
asFloat (none) FloatfloatdoubleDoubledouble random FloatfloatdoubleDoubledouble value in the range (0.0, 1.0)
asInt IntintintIntegerint, IntintintIntegerint IntintintIntegerint random IntintintIntegerint value in the range of the arguments
nextGen (none) RandomRandomRandomRandomRandom a new instance of RandomRandomRandomRandomRandom for subsequent use

Example using RandomRandomRandomRandomRandom

   ● To roll a dice 20 times in a function that returns a 2-tuple of random value and a new instance of RandomRandomRandomRandomRandom:

+main 1 variable rndname? set to new Random()value or expression?2 call rnd.initialiseFromClockprocedureName?(arguments?)3 +for iitem? in range(1, 20)source? 4 print(randomThrow(rnd).item_0value or expression?)5 assign rndvariableName? to randomThrow(rnd).item_1value or expression?6 end for end main +function randomThrowname?(rnd as Randomparameter definitions?) returns (Int, Random)Type? 7 return (rnd.asInt(1, 6), rnd.nextGen())value or expression?8 end function
+def main() -> None: 1 rndname? = Random()value or expression? # variable definition2 rnd.initialiseFromClockprocedureName?(arguments?) # procedure call3 +for iitem? in range(1, 20)source?: 4 print(randomThrow(rnd).item_0value or expression?)5 rndvariableName? = randomThrow(rnd).item_1value or expression? # assignment6 # end for # end main +def randomThrowname?(rnd: Randomparameter definitions?) -> tuple[int, Random]Type?: # function7 return (rnd.asInt(1, 6), rnd.nextGen())value or expression?8 # end function main()
+static void main() { 1 var rndname? = new Random()value or expression?;2 rnd.initialiseFromClockprocedureName?(arguments?); // procedure call3 +foreach (var iitem? in range(1, 20)source?) { 4 Console.WriteLine(randomThrow(rnd).item_0value or expression?); // print statement5 rndvariableName? = randomThrow(rnd).item_1value or expression?; // assignment6 } // end foreach } // end main +static (int, Random)Type? randomThrowname?(Random rndparameter definitions?) { // function7 return (rnd.asInt(1, 6), rnd.nextGen())value or expression?;8 } // end function
+Sub main() 1 Dim rndname? = New Random()value or expression? ' variable definition2 rnd.initialiseFromClockprocedureName?(arguments?) ' procedure call3 +For Each iitem? In range(1, 20)source? 4 Console.WriteLine(randomThrow(rnd).item_0value or expression?) ' print statement5 rndvariableName? = randomThrow(rnd).item_1value or expression? ' assignment6 Next i End Sub +Function randomThrowname?(rnd As Randomparameter definitions?) As (Integer, Random)Type? 7 Return (rnd.asInt(1, 6), rnd.nextGen())value or expression?8 End Function
public class Global {

+static void main() { 1 var rndname? = new Random()value or expression?;2 rnd.initialiseFromClockprocedureName?(arguments?); // procedure call3 +foreach (var iitem? in range(1, 20)source?) { 4 System.out.println(randomThrow(rnd).item_0value or expression?); // print statement5 rndvariableName? = randomThrow(rnd).item_1value or expression?; // assignment6 } // end foreach } // end main +static (int, Random)Type? randomThrowname?(Random rndparameter definitions?) { // function7 return (rnd.asInt(1, 6), rnd.nextGen())value or expression?;8 } // end function
} // end Global

Input/output

This section covers a variety of input and output facilities:

Keyboard input

soliciting and retrieving keyboard input requires using these system methods:

system
method		 argument
types		 return
types		 action
getKey (none) StringstrstringStringString returns the last character last pressed on the keyboard during program execution
getKeyWithModifier (none) 2-tuple:
(StringstrstringStringString, StringstrstringStringString)		 returns the last key combination pressed on the keyboard:
the key pressed and the modifier key's name (if also pressed)
getNumericKey (none) StringstrstringStringString returns either the numeric key last pressed or, if the last pressed key was not numeric, then "-1"
input StringstrstringStringString StringstrstringStringString prints the string as a prompt, and returns the typed input when Enter is pressed, similar to the input statement.
inputStringWithLimits StringstrstringStringString, IntintintIntegerint, IntintintIntegerint StringstrstringStringString prints the string as a prompt and returns the typed input when Enter is pressed
provided the length of the response is within the minimum and maximum limits specified.
If it is not, the prompt is repeated with the relevant limit displayed
inputStringFromOptions StringstrstringStringString, List<of String>list[str]List<string>List(Of String)List<String> StringstrstringStringString prints the string as a prompt and returns the typed input when Enter is pressed
provided it is one of the options in the ListlistListListList.
If it is not, the prompt is repeated with the options displayed
inputInt StringstrstringStringString IntintintIntegerint prints the string as a prompt and returns the value of the typed input when Enter is pressed
provided that it is an integer.
If it is not, the prompt is repeated with an error message
inputIntBetween StringstrstringStringString, IntintintIntegerint, IntintintIntegerint IntintintIntegerint prints the string as a prompt and returns the value of the typed input when Enter is pressed
provided that it is an integer with a value in the (inclusive) range.
The first range value must be less than or equal to the second
inputFloat StringstrstringStringString FloatfloatdoubleDoubledouble prints the string as a prompt and returns the value of the typed input when Enter is pressed
provided that it is a number.
If it is not, the prompt is repeated with an error message
inputFloatBetween StringstrstringStringString, IntintintIntegerint, IntintintIntegerint FloatfloatdoubleDoubledouble prints the string as a prompt and returns the value of the typed input when Enter is pressed
provided that it is a number with a value in the (inclusive) range.
The first range value must be less than or equal to the second
waitForKey (none) StringstrstringStringString pauses execution of the program until a key is pressed on the keyboard,
and returns either a character or the name of a non-character key

Reading keys 'on the fly'

In some applications – especially in games, for example – you want the program to react to a key pressed by the user, but without holding up the program to wait for value to be input.

Whether your application makes use of graphics, or uses the display just for text, reading keystrokes 'on the fly' is done via one of the three methods shown here:

+main 9 variable key1name? set to getKey()value or expression?10 variable key2name? set to getNumericKey()value or expression?11 variable kmname? set to getKeyWithModifier()value or expression?12 variable keyCapname? set to km.item_0value or expression?13 variable keyModname? set to km.item_1value or expression?14 end main
+def main() -> None: 15 key1name? = getKey()value or expression? # variable definition16 key2name? = getNumericKey()value or expression? # variable definition17 kmname? = getKeyWithModifier()value or expression? # variable definition18 keyCapname? = km.item_0value or expression? # variable definition19 keyModname? = km.item_1value or expression? # variable definition20 # end main
+static void main() { 21 var key1name? = getKey()value or expression?;22 var key2name? = getNumericKey()value or expression?;23 var kmname? = getKeyWithModifier()value or expression?;24 var keyCapname? = km.item_0value or expression?;25 var keyModname? = km.item_1value or expression?;26 } // end main
+Sub main() 27 Dim key1name? = getKey()value or expression? ' variable definition28 Dim key2name? = getNumericKey()value or expression? ' variable definition29 Dim kmname? = getKeyWithModifier()value or expression? ' variable definition30 Dim keyCapname? = km.item_0value or expression? ' variable definition31 Dim keyModname? = km.item_1value or expression? ' variable definition32 End Sub
+static void main() { 33 var key1name? = getKey()value or expression?;34 var key2name? = getNumericKey()value or expression?;35 var kmname? = getKeyWithModifier()value or expression?;36 var keyCapname? = km.item_0value or expression?;37 var keyModname? = km.item_1value or expression?;38 } // end main
+main 39 call pressAnyKeyToContinueprocedureName?(arguments?)40 print("OK, press A or B"value or expression?)41 variable keyname? set to waitForKey()value or expression?42 print($"That was {key}"value or expression?)43 end main
+def main() -> None: 44 pressAnyKeyToContinueprocedureName?(arguments?) # procedure call45 print("OK, press A or B"value or expression?)46 keyname? = waitForKey()value or expression? # variable definition47 print(f"That was {key}"value or expression?)48 # end main
+static void main() { 49 pressAnyKeyToContinueprocedureName?(arguments?); // procedure call50 Console.WriteLine("OK, press A or B"value or expression?); // print statement51 var keyname? = waitForKey()value or expression?;52 Console.WriteLine($"That was {key}"value or expression?); // print statement53 } // end main
+Sub main() 54 pressAnyKeyToContinueprocedureName?(arguments?) ' procedure call55 Console.WriteLine("OK, press A or B"value or expression?) ' print statement56 Dim keyname? = waitForKey()value or expression? ' variable definition57 Console.WriteLine($"That was {key}"value or expression?) ' print statement58 End Sub
+static void main() { 59 pressAnyKeyToContinueprocedureName?(arguments?); // procedure call60 System.out.println("OK, press A or B"value or expression?); // print statement61 var keyname? = waitForKey()value or expression?;62 System.out.println(String.format("That was %", key)value or expression?); // print statement63 } // end main

Text file input/output

Reading or writing a text file requires that you open (for reading) or create (for writing) a file using these system methods:

system
method		 argument
types		 return
class		 action
createFileForWriting StringstrstringStringString TextFileWriterTextFileWriterTextFileWriterTextFileWriterTextFileWriter sets up a buffer for the data to be output, and specifies a filename (or the empty string) with or without the default filetype of .txt, and returns a file handle
see Writing text files
openFileForReading (none) TextFileReaderTextFileReaderTextFileReaderTextFileReaderTextFileReader opens a file system dialog to choose the filename of filetype .txt to be read, and returns a file handle
see Reading text files

Writing text files

The TextFileWriterTextFileWriterTextFileWriterTextFileWriterTextFileWriter class is used to write textual data to a file.

An instance is created by the system method createFileForWriting.

The available procedure methods are:

procedure
method		 argument
type		 action
writeLine StringstrstringStringString writes the string to the buffer
writeWholeFile StringstrstringStringString writes the string to the buffer and then outputs the buffer to the file system
saveAndClose none writes the buffer to the file system

These methods may be used to write a whole file in one go:

+main 64 variable filename? set to createFileForWriting("myFile.txt")value or expression?65 call file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?)66 end main
+def main() -> None: 67 filename? = createFileForWriting("myFile.txt")value or expression? # variable definition68 file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?) # procedure call69 # end main
+static void main() { 70 var filename? = createFileForWriting("myFile.txt")value or expression?;71 file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?); // procedure call72 } // end main
+Sub main() 73 Dim filename? = createFileForWriting("myFile.txt")value or expression? ' variable definition74 file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?) ' procedure call75 End Sub
+static void main() { 76 var filename? = createFileForWriting("myFile.txt")value or expression?;77 file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?); // procedure call78 } // end main

Notes

Reading text files

The TextFileReaderTextFileReaderTextFileReaderTextFileReaderTextFileReader class is used to read text data from a file with type extension .txt.

An instance is created by the system method openFileForReading.

The available procedure methods are:

procedure
method		 argument
type		 action
readLine (none) reads the next substring from the file that is terminated with a newline
readWholeFile (none) reads the whole file and closes the file
endOfFile (none) returns trueTruetrueTruetrue after the last line has been read
– otherwise falseFalsefalseFalsefalse
close (none) closes the file

These methods may be used to read a whole file in one go:

+main 119 variable filename? set to openFileForReading()value or expression?120 variable textname? set to file.readWholeFile()value or expression?121 print(textvalue or expression?)122 end main
+def main() -> None: 123 filename? = openFileForReading()value or expression? # variable definition124 textname? = file.readWholeFile()value or expression? # variable definition125 print(textvalue or expression?)126 # end main
+static void main() { 127 var filename? = openFileForReading()value or expression?;128 var textname? = file.readWholeFile()value or expression?;129 Console.WriteLine(textvalue or expression?); // print statement130 } // end main
+Sub main() 131 Dim filename? = openFileForReading()value or expression? ' variable definition132 Dim textname? = file.readWholeFile()value or expression? ' variable definition133 Console.WriteLine(textvalue or expression?) ' print statement134 End Sub
+static void main() { 135 var filename? = openFileForReading()value or expression?;136 var textname? = file.readWholeFile()value or expression?;137 System.out.println(textvalue or expression?); // print statement138 } // end main

Notes

Rendering Html in the display

If you embed Html code in a string and then attempt to print it, you will see the string displayed literally: the Html tags will not be recognised. This is for security reasons. However, it is possible to display formatted Html in the display. The following code:

call displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?)139
displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?) # procedure call140
displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?); // procedure call141
displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?) ' procedure call142
displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?); // procedure call143

will produce:

Html 1

This Html forms another 'layer' in the IDE's display pane. Any plain text that you print (using call procedure print() or any of the print procedures) will be overlaid on top of this.

You can clear just the Html layer in the display using the procedure clearHtml .

For specifying style or other attributes within Html tags, the attribute values should be enclosed in single quotation marks ' as shown above. Html will recognise single or double quotation marks, but entering double quotation marks would terminate the Elan string. Alternatively, you could use the constant quotesquotesquotesquotesquotes within curly braces as an interpolated field .

Using an embedded CSS stylesheet

You can also specify a <style> tag at the start of your Html string, to apply to the whole Html being displayed. In this case you would put the style definition into a named value as a literal but enclosed in single quotes, for example:

+main 144 variable stylename? set to "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression?145 call displayHtmlprocedureName?($"{style}<h1>New heading</h1><p>some new text</p>"arguments?)146 end main
+def main() -> None: 147 stylename? = "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression? # variable definition148 displayHtmlprocedureName?(f"{style}<h1>New heading</h1><p>some new text</p>"arguments?) # procedure call149 # end main
+static void main() { 150 var stylename? = "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression?;151 displayHtmlprocedureName?($"{style}<h1>New heading</h1><p>some new text</p>"arguments?); // procedure call152 } // end main
+Sub main() 153 Dim stylename? = "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression? ' variable definition154 displayHtmlprocedureName?($"{style}<h1>New heading</h1><p>some new text</p>"arguments?) ' procedure call155 End Sub
+static void main() { 156 var stylename? = "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression?;157 displayHtmlprocedureName?(String.format("%<h1>New heading</h1><p>some new text</p>", style)arguments?); // procedure call158 } // end main

will produce:

Html 2

Displaying images from URLs

An image that can be retrieved with an http or https URL may be sent to the display, though note that other URI schemes, such as in file://host/path to access an image from your local file system, are not supported. Here are two techniques:

Sound

The tone procedure allows the generation of a simple tone. It requires three arguments to be provided:

Note that the volume parameter is only relative in that the actual volume will be modified by the various sound settings on the output device, and may even be muted.

Example using tone

   ● An example that plays a C major scale first ascending then descending:

+main 209 variable scalename? set to [262, 294, 330, 349, 392, 440, 494, 523]value or expression?210 variable scaleLname? set to scale.length()value or expression?211 variable quavername? set to 250value or expression?212 variable volumename? set to 1.5value or expression?213 +for iitem? in range(0, scaleL)source? 214 call toneprocedureName?(quaver, scale[i], volumearguments?)215 end for call sleepprocedureName?(1arguments?)216 +for iitem? in range(0, scaleL)source? 217 call toneprocedureName?(quaver, scale[scaleL - 1 - i], volumearguments?)218 end for end main
+def main() -> None: 219 scalename? = [262, 294, 330, 349, 392, 440, 494, 523]value or expression? # variable definition220 scaleLname? = scale.length()value or expression? # variable definition221 quavername? = 250value or expression? # variable definition222 volumename? = 1.5value or expression? # variable definition223 +for iitem? in range(0, scaleL)source?: 224 toneprocedureName?(quaver, scale[i], volumearguments?) # procedure call225 # end for sleepprocedureName?(1arguments?) # procedure call226 +for iitem? in range(0, scaleL)source?: 227 toneprocedureName?(quaver, scale[scaleL - 1 - i], volumearguments?) # procedure call228 # end for # end main
+static void main() { 229 var scalename? = new [] {262, 294, 330, 349, 392, 440, 494, 523}value or expression?;230 var scaleLname? = scale.length()value or expression?;231 var quavername? = 250value or expression?;232 var volumename? = 1.5value or expression?;233 +foreach (var iitem? in range(0, scaleL)source?) { 234 toneprocedureName?(quaver, scale[i], volumearguments?); // procedure call235 } // end foreach sleepprocedureName?(1arguments?); // procedure call236 +foreach (var iitem? in range(0, scaleL)source?) { 237 toneprocedureName?(quaver, scale[scaleL - 1 - i], volumearguments?); // procedure call238 } // end foreach } // end main
+Sub main() 239 Dim scalename? = {262, 294, 330, 349, 392, 440, 494, 523}value or expression? ' variable definition240 Dim scaleLname? = scale.length()value or expression? ' variable definition241 Dim quavername? = 250value or expression? ' variable definition242 Dim volumename? = 1.5value or expression? ' variable definition243 +For Each iitem? In range(0, scaleL)source? 244 toneprocedureName?(quaver, scale(i), volumearguments?) ' procedure call245 Next i sleepprocedureName?(1arguments?) ' procedure call246 +For Each iitem? In range(0, scaleL)source? 247 toneprocedureName?(quaver, scale(scaleL - 1 - i), volumearguments?) ' procedure call248 Next i End Sub
+static void main() { 249 var scalename? = list(262, 294, 330, 349, 392, 440, 494, 523)value or expression?;250 var scaleLname? = scale.length()value or expression?;251 var quavername? = 250value or expression?;252 var volumename? = 1.5value or expression?;253 +foreach (var iitem? in range(0, scaleL)source?) { 254 toneprocedureName?(quaver, scale[i], volumearguments?); // procedure call255 } // end foreach sleepprocedureName?(1arguments?); // procedure call256 +foreach (var iitem? in range(0, scaleL)source?) { 257 toneprocedureName?(quaver, scale[scaleL - 1 - i], volumearguments?); // procedure call258 } // end foreach } // end main

Common methods

Common dot methods

Click on a type to go to the type's function dot methods, or on  to go to the specific method on that type.

Dot method Value type Reference type Tuple
IntintintIntegerint FloatfloatdoubleDoubledouble BooleanboolboolBooleanboolean StringstrstringStringString ListlistListListList DictionaryDictionaryDictionaryDictionaryDictionary HashSetHashSetHashSetHashSetHashSet StackStackStackStackStack QueueQueueQueueQueueQueue
ceiling note 2.
contains note 4.
equals
floor note 2.
indexOf
isInfinite note 2.
isNan note 2.
length note 3.
notEqualTo
peek
round note 2.
toString note 1.
withPut note 5.
withRemoveAt

Notes

  1. The method toString is so widely applicable because it enables you to print all variables and data structures to the IDE's display pane for debugging purposes.
  2. methods ceiling, floor, isInfinite, isNaN and round are designed for use on FloatfloatdoubleDoubledouble values, but they can accept IntintintIntegerint values without raising an error.
  3. The length of a DictionaryDictionaryDictionaryDictionaryDictionary can be found by applying method length to the ListlistListListList returned by method keys on the dictionary:
    print(di.keys().length())print(di.keys().length())print(di.keys().length())print(di.keys().length())print(di.keys().length())⟶15
  4. Checking whether an item is contained in a DictionaryDictionaryDictionaryDictionaryDictionary can be done by applying method contains to the ListlistListListList returned by methods keys and values on the dictionary:
    print(di.keys().contains("widget"))print(di.keys().contains("widget"))print(di.keys().contains("widget"))print(di.keys().contains("widget"))print(di.keys().contains("widget"))⟶true or false
    print(di.values().contains(42))print(di.values().contains(42))print(di.values().contains(42))print(di.values().contains(42))print(di.values().contains(42))⟶true or false
  5. withPut supersedes the deprecated withSet

Library procedures

All procedures are accessed via a callcallcallcallcall instruction.

Standalone procedures

procedureinput
argument
types		output
argument
types		action
clearPrintedText (none) (none) clears the IDE's display pane
clearBlocks (none) (none) clears the block graphics layer of the IDE's display pane
clearVectorGraphics (none) (none) clears the vector graphics layer of the IDE's display pane
clearHtml (none) (none) clears the Html layer of the IDE's display pane
clearAllDisplays (none) (none) clears display pane as well as the blocks, vector graphics and Html layers
clearKeyBuffer (none) (none) clears the IDE's keyboard input
pressAnyKeyToContinue BooleanboolboolBooleanboolean (none) pauses execution of the program until a keyboard key is pressed
if the argument is trueTruetrueTruetrue 'Press any key to continue' is first displayed,
if falseFalsefalseFalsefalse nothing is displayed
printNoLine StringstrstringStringString (none) prints the string to the display without appending a newline so
a following call will output on the same line.
You can put your own \n newlines in the argument string
printTab IntintintIntegerint, StringstrstringStringString (none) prints the string to the display starting at the tab position given (from 0)
without appending a newline
sleep IntintintIntegerint (none) pauses the execution of the program for the specified number of seconds,
e.g. for a game sleep(1.5)sleep(1.5)sleep(1.5)sleep(1.5)sleep(1.5) delays execution for 1.5 seconds
sleep_ms IntintintIntegerint (none) pauses the execution of the program for the specified number of milliseconds,
e.g. sleep(100)sleep(100)sleep(100)sleep(100)sleep(100) delays execution for one tenth of a second

Examples using print and printTab

   ● Procedure print sends text strings to the display pane:

+main 259 print("Hello"value or expression?)260 variable aname? set to 3value or expression?261 variable bname? set to 4value or expression?262 print(a*bvalue or expression?)263 print($"{a} times {b}) equals {a*b}"value or expression?)264 variable tname? set to (true, 42)value or expression?265 print(t.item_0value or expression?)266 print(t.item_1value or expression?)267 end main
+def main() -> None: 268 print("Hello"value or expression?)269 aname? = 3value or expression? # variable definition270 bname? = 4value or expression? # variable definition271 print(a*bvalue or expression?)272 print(f"{a} times {b}) equals {a*b}"value or expression?)273 tname? = (True, 42)value or expression? # variable definition274 print(t.item_0value or expression?)275 print(t.item_1value or expression?)276 # end main
+static void main() { 277 Console.WriteLine("Hello"value or expression?); // print statement278 var aname? = 3value or expression?;279 var bname? = 4value or expression?;280 Console.WriteLine(a*bvalue or expression?); // print statement281 Console.WriteLine($"{a} times {b}) equals {a*b}"value or expression?); // print statement282 var tname? = (true, 42)value or expression?;283 Console.WriteLine(t.item_0value or expression?); // print statement284 Console.WriteLine(t.item_1value or expression?); // print statement285 } // end main
+Sub main() 286 Console.WriteLine("Hello"value or expression?) ' print statement287 Dim aname? = 3value or expression? ' variable definition288 Dim bname? = 4value or expression? ' variable definition289 Console.WriteLine(a*bvalue or expression?) ' print statement290 Console.WriteLine($"{a} times {b}) equals {a*b}"value or expression?) ' print statement291 Dim tname? = (True, 42)value or expression? ' variable definition292 Console.WriteLine(t.item_0value or expression?) ' print statement293 Console.WriteLine(t.item_1value or expression?) ' print statement294 End Sub
+static void main() { 295 System.out.println("Hello"value or expression?); // print statement296 var aname? = 3value or expression?;297 var bname? = 4value or expression?;298 System.out.println(a*bvalue or expression?); // print statement299 System.out.println(String.format("% times %) equals %", a, b, a*b)value or expression?); // print statement300 var tname? = (true, 42)value or expression?;301 System.out.println(t.item_0value or expression?); // print statement302 System.out.println(t.item_1value or expression?); // print statement303 } // end main
⟶


⟶
⟶

⟶
⟶		 Hello


12
3 times 4 equals 12 [using interpolated strings ]
[defining a 2-tuple ]
true
42

   ● Procedure printTab helps in the layout of information printed to the display, e.g. when printing columns of data:

+main 304 call printTabprocedureName?(0, "Number"arguments?)305 call printTabprocedureName?(10, "Square"arguments?)306 call printTabprocedureName?(20, "Cube\n"arguments?)307 +for iitem? in range(1, 11)source? 308 call printTabprocedureName?(0, i.toString()arguments?)309 call printTabprocedureName?(10, $"{pow(i, 2)}"arguments?)310 call printTabprocedureName?(20, $"{pow(i, 3)}\n"arguments?)311 end for end main
+def main() -> None: 312 printTabprocedureName?(0, "Number"arguments?) # procedure call313 printTabprocedureName?(10, "Square"arguments?) # procedure call314 printTabprocedureName?(20, "Cube\n"arguments?) # procedure call315 +for iitem? in range(1, 11)source?: 316 printTabprocedureName?(0, i.toString()arguments?) # procedure call317 printTabprocedureName?(10, f"{pow(i, 2)}"arguments?) # procedure call318 printTabprocedureName?(20, f"{pow(i, 3)}\n"arguments?) # procedure call319 # end for # end main
+static void main() { 320 printTabprocedureName?(0, "Number"arguments?); // procedure call321 printTabprocedureName?(10, "Square"arguments?); // procedure call322 printTabprocedureName?(20, "Cube\n"arguments?); // procedure call323 +foreach (var iitem? in range(1, 11)source?) { 324 printTabprocedureName?(0, i.toString()arguments?); // procedure call325 printTabprocedureName?(10, $"{pow(i, 2)}"arguments?); // procedure call326 printTabprocedureName?(20, $"{pow(i, 3)}\n"arguments?); // procedure call327 } // end foreach } // end main
+Sub main() 328 printTabprocedureName?(0, "Number"arguments?) ' procedure call329 printTabprocedureName?(10, "Square"arguments?) ' procedure call330 printTabprocedureName?(20, "Cube\n"arguments?) ' procedure call331 +For Each iitem? In range(1, 11)source? 332 printTabprocedureName?(0, i.toString()arguments?) ' procedure call333 printTabprocedureName?(10, $"{pow(i, 2)}"arguments?) ' procedure call334 printTabprocedureName?(20, $"{pow(i, 3)}\n"arguments?) ' procedure call335 Next i End Sub
+static void main() { 336 printTabprocedureName?(0, "Number"arguments?); // procedure call337 printTabprocedureName?(10, "Square"arguments?); // procedure call338 printTabprocedureName?(20, "Cube\n"arguments?); // procedure call339 +foreach (var iitem? in range(1, 11)source?) { 340 printTabprocedureName?(0, i.toString()arguments?); // procedure call341 printTabprocedureName?(10, String.format("%", pow(i, 2))arguments?); // procedure call342 printTabprocedureName?(20, String.format("%\n", pow(i, 3))arguments?); // procedure call343 } // end foreach } // end main

   ● For numeric output, it is preferable to right-align the columns, e.g. when listing powers of 9:

+main 1 variable tabname? set to 10value or expression?2 +for iitem? in range(1, tab)source? 3 variable jname? set to pow(9, i).floor()value or expression?4 call printTabprocedureName?(tab - strLen(j), $"{j}\n"arguments?)5 end for end main +function strLenname?(j as Intparameter definitions?) returns IntType? 6 return j.toString().length()value or expression?7 end function
+def main() -> None: 1 tabname? = 10value or expression? # variable definition2 +for iitem? in range(1, tab)source?: 3 jname? = pow(9, i).floor()value or expression? # variable definition4 printTabprocedureName?(tab - strLen(j), f"{j}\n"arguments?) # procedure call5 # end for # end main +def strLenname?(j: intparameter definitions?) -> intType?: # function6 return j.toString().length()value or expression?7 # end function main()
+static void main() { 1 var tabname? = 10value or expression?;2 +foreach (var iitem? in range(1, tab)source?) { 3 var jname? = pow(9, i).floor()value or expression?;4 printTabprocedureName?(tab - strLen(j), $"{j}\n"arguments?); // procedure call5 } // end foreach } // end main +static intType? strLenname?(int jparameter definitions?) { // function6 return j.toString().length()value or expression?;7 } // end function
+Sub main() 1 Dim tabname? = 10value or expression? ' variable definition2 +For Each iitem? In range(1, tab)source? 3 Dim jname? = pow(9, i).floor()value or expression? ' variable definition4 printTabprocedureName?(tab - strLen(j), $"{j}\n"arguments?) ' procedure call5 Next i End Sub +Function strLenname?(j As Integerparameter definitions?) As IntegerType? 6 Return j.toString().length()value or expression?7 End Function
public class Global {

+static void main() { 1 var tabname? = 10value or expression?;2 +foreach (var iitem? in range(1, tab)source?) { 3 var jname? = pow(9, i).floor()value or expression?;4 printTabprocedureName?(tab - strLen(j), String.format("%\n", j)arguments?); // procedure call5 } // end foreach } // end main +static intType? strLenname?(int jparameter definitions?) { // function6 return j.toString().length()value or expression?;7 } // end function
} // end Global

Type instance procedures

Procedures applicable to standard Reference types are linked from:

User-defined classes may have procedures that can be applied to their class instances.

Library methods

These methods may be referenced from within a function.

Standalone functions

Standalone library functions always return a value and are therefore used in contexts that expect a value, such as in the right-hand side of a variable definition declaration or an assign variable, either on their own or within a more complex expression.

Standalone library functions require at least one argument to be passed (in round brackets), corresponding to the parameters defined for that function.

These methods are pure functions and so may be referenced in your functions as well as in procedures:

library
method		 argument
types		 return
types		 returns
copy named value of any type same type as argument a copy of the named value
createBlockGraphics IntintintIntegerint List<of List<of Int>>list[list[int]]List<List<int>>List(Of List(Of Integer))List<List<int>> a 40×30 array with the specified value in every cell
createDictionary ListlistListListList of 2-tuples, each containg a key:value pair new codenew codenew codenew code
public class Global {

new code
} // end Global		 a Dictionary containing the specified key:value pairs
createPopulatedList IntintintIntegerint,
value of ListlistListListList item's type		 new codenew codenew codenew code
public class Global {

new code
} // end Global		 a ListlistListListList containing the specified number of items each initialised to the value in the second argument
createPopulatedListofLists IntintintIntegerint, IntintintIntegerint,
value of ListlistListListList item's type		 new codenew codenew codenew code
public class Global {

new code
} // end Global		 a ListlistListListList of length the first argument containing that number of ListlistListListLists
each initialised to a ListlistListListList of length the second argument
with each item therein initialised to the value in the third argument
max List<of Int>list[int]List<int>List(Of Integer)List<int> or
List<of Float>list[float]List<double>List(Of Double)List<double>		 IntintintIntegerint or
FloatfloatdoubleDoubledouble		 the maximum value found in the ListlistListListList
min List<of Int>list[int]List<int>List(Of Integer)List<int> or
List<of Float>list[float]List<double>List(Of Double)List<double>		 IntintintIntegerint or
FloatfloatdoubleDoubledouble		 the minimum value found in the ListlistListListList
range IntintintIntegerint, IntintintIntegerint ListlistListListList a ListlistListListList containing the integers from the first argument to one less than the second argument.
If the second argument is not greater than the first, then the empty ListlistListListList is returned
rangeInSteps IntintintIntegerint, IntintintIntegerint, IntintintIntegerint ListlistListListList a ListlistListListList containing the integers from the first argument to one less than the second argument
in increments specified by the third argument.
If the third argument is negative, the second argument must be less than the first,
and the integers returned will run from the first to one more than the second
unicode IntintintIntegerint StringstrstringStringString a string containing the one character defined at the given Unicode code point

Examples using standalone functions

   ● Test assertions that use methods asInt and asFloat:

+test test_parsetest_name? 8 assert asInt("31")actual (computed) value? evaluates to 31expected value? not run9 assert asInt("0")actual (computed) value? evaluates to 0expected value? not run10 assert asFloat("31")actual (computed) value? evaluates to 31expected value? not run11 assert asFloat("0")actual (computed) value? evaluates to 0expected value? not run12 assert asFloat("3.1")actual (computed) value? evaluates to 3.1expected value? not run13 end test
+class Test_parse(unittest.TestCase):
 def test_parsetest_name?(self) -> None: 14 self.assertEqual(asInt("31")actual (computed) value?, 31expected value?) not run15 self.assertEqual(asInt("0")actual (computed) value?, 0expected value?) not run16 self.assertEqual(asFloat("31")actual (computed) value?, 31expected value?) not run17 self.assertEqual(asFloat("0")actual (computed) value?, 0expected value?) not run18 self.assertEqual(asFloat("3.1")actual (computed) value?, 3.1expected value?) not run19 # end test
+[TestClass] class Test_parse
[TestMethod] static void test_parsetest_name?() { 20 Assert.AreEqual(31expected value?, asInt("31")actual (computed) value?); not run21 Assert.AreEqual(0expected value?, asInt("0")actual (computed) value?); not run22 Assert.AreEqual(31expected value?, asFloat("31")actual (computed) value?); not run23 Assert.AreEqual(0expected value?, asFloat("0")actual (computed) value?); not run24 Assert.AreEqual(3.1expected value?, asFloat("3.1")actual (computed) value?); not run25 }} // end test
+<TestClass Class Test_parse
 <TestMethod> Sub test_parsetest_name?() 26 Assert.AreEqual(31expected value?, asInt("31")actual (computed) value?) not run27 Assert.AreEqual(0expected value?, asInt("0")actual (computed) value?) not run28 Assert.AreEqual(31expected value?, asFloat("31")actual (computed) value?) not run29 Assert.AreEqual(0expected value?, asFloat("0")actual (computed) value?) not run30 Assert.AreEqual(3.1expected value?, asFloat("3.1")actual (computed) value?) not run31  End Sub
End Class
+class Test_parse {
@Test static void test_parsetest_name?() { 32 assertEquals(31expected value?, asInt("31")actual (computed) value?); not run33 assertEquals(0expected value?, asInt("0")actual (computed) value?); not run34 assertEquals(31expected value?, asFloat("31")actual (computed) value?); not run35 assertEquals(0expected value?, asFloat("0")actual (computed) value?); not run36 assertEquals(3.1expected value?, asFloat("3.1")actual (computed) value?); not run37 }} // end test
Notes

   ● Using method unicode:

print(unicode(0x2665))print(unicode(0x2665))print(unicode(0x2665))print(unicode(&H2665))print(unicode(0x2665))⟶♥

   ● Print every second item in a ListlistListListList:

+main 38 variable numbersname? set to ["zero", "one", "two", "three", "four", "five", "six"]value or expression?39 +for nitem? in rangeInSteps(0, numbers.length() + 1, 2)source? 40 print(numbers[n]value or expression?)41 end for end main
+def main() -> None: 42 numbersname? = ["zero", "one", "two", "three", "four", "five", "six"]value or expression? # variable definition43 +for nitem? in rangeInSteps(0, numbers.length() + 1, 2)source?: 44 print(numbers[n]value or expression?)45 # end for # end main
+static void main() { 46 var numbersname? = new [] {"zero", "one", "two", "three", "four", "five", "six"}value or expression?;47 +foreach (var nitem? in rangeInSteps(0, numbers.length() + 1, 2)source?) { 48 Console.WriteLine(numbers[n]value or expression?); // print statement49 } // end foreach } // end main
+Sub main() 50 Dim numbersname? = {"zero", "one", "two", "three", "four", "five", "six"}value or expression? ' variable definition51 +For Each nitem? In rangeInSteps(0, numbers.length() + 1, 2)source? 52 Console.WriteLine(numbers(n)value or expression?) ' print statement53 Next n End Sub
+static void main() { 54 var numbersname? = list("zero", "one", "two", "three", "four", "five", "six")value or expression?;55 +foreach (var nitem? in rangeInSteps(0, numbers.length() + 1, 2)source?) { 56 System.out.println(numbers[n]value or expression?); // print statement57 } // end foreach } // end main

   ● Using the Higher-order Function filter to print the prime numbers less than a given limit:

+main 1 print(primesFromList(range(2, 100))value or expression?)2 end main +function primesFromListname?(li as List<of Int>parameter definitions?) returns List<of Int>Type? 3 # returns primes from the list assuming it starts with a prime (e.g. 2)comment? return if_(li.length() is 0, li, [li.head()].withAppendList(primesFromList(li.tail().filter(lambda n as Int => (n mod li.head()) > 0))))value or expression?4 end function
+def main() -> None: 1 print(primesFromList(range(2, 100))value or expression?)2 # end main +def primesFromListname?(li: list[int]parameter definitions?) -> list[int]Type?: # function3 # returns primes from the list assuming it starts with a prime (e.g. 2)comment? return if_(li.length() == 0, li, [li.head()].withAppendList(primesFromList(li.tail().filter(lambda n: int: (n % li.head()) > 0))))value or expression?4 # end function main()
+static void main() { 1 Console.WriteLine(primesFromList(range(2, 100))value or expression?); // print statement2 } // end main +static List<int>Type? primesFromListname?(List<int> liparameter definitions?) { // function3 // returns primes from the list assuming it starts with a prime (e.g. 2)comment? return if_(li.length() == 0, li, new [] {li.head()}.withAppendList(primesFromList(li.tail().filter(int n => (n % li.head()) > 0))))value or expression?;4 } // end function
+Sub main() 1 Console.WriteLine(primesFromList(range(2, 100))value or expression?) ' print statement2 End Sub +Function primesFromListname?(li As List(Of Integer)parameter definitions?) As List(Of Integer)Type? 3 ' returns primes from the list assuming it starts with a prime (e.g. 2)comment? Return if_(li.length() = 0, li, {li.head()}.withAppendList(primesFromList(li.tail().filter(Function (n As Integer) (n Mod li.head()) > 0))))value or expression?4 End Function
public class Global {

+static void main() { 1 System.out.println(primesFromList(range(2, 100))value or expression?); // print statement2 } // end main +static List<int>Type? primesFromListname?(List<int> liparameter definitions?) { // function3 // returns primes from the list assuming it starts with a prime (e.g. 2)comment? return if_(li.length() == 0, li, list(li.head()).withAppendList(primesFromList(li.tail().filter((int n) -> (n % li.head()) > 0))))value or expression?;4 } // end function
} // end Global

Maths functions

All the maths functions expect FloatfloatdoubleDoubledouble arguments, but IntintintIntegerint arguments are accepted. They all return a value of type FloatfloatdoubleDoubledouble, except for divAsInt which returns an IntintintIntegerint.

functionargument
type		input
unit		returnsoutput
unit
absFloatfloatdoubleDoubledoubleabsolute value of the input
divAsFloatFloatfloatdoubleDoubledouble, FloatfloatdoubleDoubledoublefirst input value divided by second input value
divAsIntFloatfloatdoubleDoubledouble, FloatfloatdoubleDoubledoublefirst input value divided by second input value
and result rounded down to integer
powFloatfloatdoubleDoubledouble, FloatfloatdoubleDoubledoubleresult of raising first input to the power of the second
sqrtFloatfloatdoubleDoubledoublepositive square root of the input
exp FloatfloatdoubleDoubledouble 𝑒𝑥 where 𝑥 is the argument and
𝑒 is Euler's number 2.718281828459045..
the base of natural logarithms
logEFloatfloatdoubleDoubledoublenatural logarithm of the input
log10FloatfloatdoubleDoubledoublebase-10 logarithm of the input
log2FloatfloatdoubleDoubledoublebase-2 logarithm of the input
sinFloatfloatdoubleDoubledoubleradianssine of the input
cosFloatfloatdoubleDoubledoubleradianscosine of the input
tanFloatfloatdoubleDoubledoubleradianstangent of the input
asinFloatfloatdoubleDoubledoublearcsine of the inputradians
acosFloatfloatdoubleDoubledoublearccosine of the inputradians
atanFloatfloatdoubleDoubledoublearctangent of the inputradians
radiansFloatfloatdoubleDoubledoubledegreesconverts input from degrees to radiansradians
degreesFloatfloatdoubleDoubledoubleradiansconverts input from radians to degreesdegrees

Examples of some maths functions and constants being tested:

+test test_mathstest_name? 5 assert piactual (computed) value? evaluates to 3.141592653589793expected value? not run6 assert abs(-3.7)actual (computed) value? evaluates to 3.7expected value? not run7 assert pow(2, 10)actual (computed) value? evaluates to 1024expected value? not run8 assert sqrt(2).round(3)actual (computed) value? evaluates to 1.414expected value? not run9 assert asin(0.5).round(3)actual (computed) value? evaluates to 0.524expected value? not run10 assert acos(0.5).round(3)actual (computed) value? evaluates to 1.047expected value? not run11 assert atan(1).round(2)actual (computed) value? evaluates to 0.79expected value? not run12 assert sin(pi/6).round(2)actual (computed) value? evaluates to 0.5expected value? not run13 assert cos(pi/4).round(3)actual (computed) value? evaluates to 0.707expected value? not run14 assert tan(pi/4).round(2)actual (computed) value? evaluates to 1expected value? not run15 assert exp(2).round(3)actual (computed) value? evaluates to 7.389expected value? not run16 assert logE(7.389).round(2)actual (computed) value? evaluates to 2expected value? not run17 assert log10(1000)actual (computed) value? evaluates to 3expected value? not run18 assert log2(65536)actual (computed) value? evaluates to 16expected value? not run19 assert log2(0x10000)actual (computed) value? evaluates to 16expected value? not run20 end test
+class Test_maths(unittest.TestCase):
 def test_mathstest_name?(self) -> None: 21 self.assertEqual(piactual (computed) value?, 3.141592653589793expected value?) not run22 self.assertEqual(abs(-3.7)actual (computed) value?, 3.7expected value?) not run23 self.assertEqual(pow(2, 10)actual (computed) value?, 1024expected value?) not run24 self.assertEqual(sqrt(2).round(3)actual (computed) value?, 1.414expected value?) not run25 self.assertEqual(asin(0.5).round(3)actual (computed) value?, 0.524expected value?) not run26 self.assertEqual(acos(0.5).round(3)actual (computed) value?, 1.047expected value?) not run27 self.assertEqual(atan(1).round(2)actual (computed) value?, 0.79expected value?) not run28 self.assertEqual(sin(pi/6).round(2)actual (computed) value?, 0.5expected value?) not run29 self.assertEqual(cos(pi/4).round(3)actual (computed) value?, 0.707expected value?) not run30 self.assertEqual(tan(pi/4).round(2)actual (computed) value?, 1expected value?) not run31 self.assertEqual(exp(2).round(3)actual (computed) value?, 7.389expected value?) not run32 self.assertEqual(logE(7.389).round(2)actual (computed) value?, 2expected value?) not run33 self.assertEqual(log10(1000)actual (computed) value?, 3expected value?) not run34 self.assertEqual(log2(65536)actual (computed) value?, 16expected value?) not run35 self.assertEqual(log2(0x10000)actual (computed) value?, 16expected value?) not run36 # end test
+[TestClass] class Test_maths
[TestMethod] static void test_mathstest_name?() { 37 Assert.AreEqual(3.141592653589793expected value?, piactual (computed) value?); not run38 Assert.AreEqual(3.7expected value?, abs(-3.7)actual (computed) value?); not run39 Assert.AreEqual(1024expected value?, pow(2, 10)actual (computed) value?); not run40 Assert.AreEqual(1.414expected value?, sqrt(2).round(3)actual (computed) value?); not run41 Assert.AreEqual(0.524expected value?, asin(0.5).round(3)actual (computed) value?); not run42 Assert.AreEqual(1.047expected value?, acos(0.5).round(3)actual (computed) value?); not run43 Assert.AreEqual(0.79expected value?, atan(1).round(2)actual (computed) value?); not run44 Assert.AreEqual(0.5expected value?, sin(pi/6).round(2)actual (computed) value?); not run45 Assert.AreEqual(0.707expected value?, cos(pi/4).round(3)actual (computed) value?); not run46 Assert.AreEqual(1expected value?, tan(pi/4).round(2)actual (computed) value?); not run47 Assert.AreEqual(7.389expected value?, exp(2).round(3)actual (computed) value?); not run48 Assert.AreEqual(2expected value?, logE(7.389).round(2)actual (computed) value?); not run49 Assert.AreEqual(3expected value?, log10(1000)actual (computed) value?); not run50 Assert.AreEqual(16expected value?, log2(65536)actual (computed) value?); not run51 Assert.AreEqual(16expected value?, log2(0x10000)actual (computed) value?); not run52 }} // end test
+<TestClass Class Test_maths
 <TestMethod> Sub test_mathstest_name?() 53 Assert.AreEqual(3.141592653589793expected value?, piactual (computed) value?) not run54 Assert.AreEqual(3.7expected value?, abs(-3.7)actual (computed) value?) not run55 Assert.AreEqual(1024expected value?, pow(2, 10)actual (computed) value?) not run56 Assert.AreEqual(1.414expected value?, sqrt(2).round(3)actual (computed) value?) not run57 Assert.AreEqual(0.524expected value?, asin(0.5).round(3)actual (computed) value?) not run58 Assert.AreEqual(1.047expected value?, acos(0.5).round(3)actual (computed) value?) not run59 Assert.AreEqual(0.79expected value?, atan(1).round(2)actual (computed) value?) not run60 Assert.AreEqual(0.5expected value?, sin(pi/6).round(2)actual (computed) value?) not run61 Assert.AreEqual(0.707expected value?, cos(pi/4).round(3)actual (computed) value?) not run62 Assert.AreEqual(1expected value?, tan(pi/4).round(2)actual (computed) value?) not run63 Assert.AreEqual(7.389expected value?, exp(2).round(3)actual (computed) value?) not run64 Assert.AreEqual(2expected value?, logE(7.389).round(2)actual (computed) value?) not run65 Assert.AreEqual(3expected value?, log10(1000)actual (computed) value?) not run66 Assert.AreEqual(16expected value?, log2(65536)actual (computed) value?) not run67 Assert.AreEqual(16expected value?, log2(&H10000)actual (computed) value?) not run68  End Sub
End Class
+class Test_maths {
@Test static void test_mathstest_name?() { 69 assertEquals(3.141592653589793expected value?, piactual (computed) value?); not run70 assertEquals(3.7expected value?, abs(-3.7)actual (computed) value?); not run71 assertEquals(1024expected value?, pow(2, 10)actual (computed) value?); not run72 assertEquals(1.414expected value?, sqrt(2).round(3)actual (computed) value?); not run73 assertEquals(0.524expected value?, asin(0.5).round(3)actual (computed) value?); not run74 assertEquals(1.047expected value?, acos(0.5).round(3)actual (computed) value?); not run75 assertEquals(0.79expected value?, atan(1).round(2)actual (computed) value?); not run76 assertEquals(0.5expected value?, sin(pi/6).round(2)actual (computed) value?); not run77 assertEquals(0.707expected value?, cos(pi/4).round(3)actual (computed) value?); not run78 assertEquals(1expected value?, tan(pi/4).round(2)actual (computed) value?); not run79 assertEquals(7.389expected value?, exp(2).round(3)actual (computed) value?); not run80 assertEquals(2expected value?, logE(7.389).round(2)actual (computed) value?); not run81 assertEquals(3expected value?, log10(1000)actual (computed) value?); not run82 assertEquals(16expected value?, log2(65536)actual (computed) value?); not run83 assertEquals(16expected value?, log2(0x10000)actual (computed) value?); not run84 }} // end test

Bitwise functions

These functions take in an integer value, and manipulate the bit representation of that value.

function argument
types		 return
type		 returns
bitAnd IntintintIntegerint, IntintintIntegerint IntintintIntegerint integer whose binary representation is the bitwise AND of the inputs
bitOr IntintintIntegerint, IntintintIntegerint IntintintIntegerint integer whose binary representation is the bitwise OR of the inputs
bitNot IntintintIntegerint IntintintIntegerint integer whose binary representation is the bitwise complement of the input
bitXor IntintintIntegerint, IntintintIntegerint IntintintIntegerint integer whose binary representation is the bitwise XOR of the inputs
bitShiftL IntintintIntegerint, IntintintIntegerint IntintintIntegerint integer bit shifted to the left by the value of the second argument,
i.e. multiplied by 2 to the power of the second argument
bitShiftR IntintintIntegerint, IntintintIntegerint IntintintIntegerint integer bit shifted to the right by the value of the second argument,
i.e. divided by 2 to the power of the second argument

Examples of the bitwise functions being tested

   ● Examples of the bitwise functions being tested

+test test_bitwisetest_name? 85 variable aname? set to 13value or expression?86 assert aactual (computed) value? evaluates to 0xdexpected value? not run87 assert aactual (computed) value? evaluates to 0b1101expected value? not run88 assert a.asBinary()actual (computed) value? evaluates to "1101"expected value? not run89 variable bname? set to 30value or expression?90 assert bactual (computed) value? evaluates to 0b11110expected value? not run91 assert bitAnd(a, b)actual (computed) value? evaluates to 0b1100expected value? not run92 variable aobname? set to bitOr(a, b)value or expression?93 assert aobactual (computed) value? evaluates to 0b11111expected value? not run94 variable axbname? set to bitXor(a, b)value or expression?95 assert axbactual (computed) value? evaluates to 0b10011expected value? not run96 variable notaname? set to bitNot(a)value or expression?97 assert notaactual (computed) value? evaluates to -14expected value? not run98 variable aLname? set to bitShiftL(a, 2)value or expression?99 assert aLactual (computed) value? evaluates to 0b110100expected value? not run100 assert bitShiftR(a, 2)actual (computed) value? evaluates to 0b11expected value? not run101 end test
+class Test_bitwise(unittest.TestCase):
 def test_bitwisetest_name?(self) -> None: 102 aname? = 13value or expression? # variable definition103 self.assertEqual(aactual (computed) value?, 0xdexpected value?) not run104 self.assertEqual(aactual (computed) value?, 0b1101expected value?) not run105 self.assertEqual(a.asBinary()actual (computed) value?, "1101"expected value?) not run106 bname? = 30value or expression? # variable definition107 self.assertEqual(bactual (computed) value?, 0b11110expected value?) not run108 self.assertEqual(bitAnd(a, b)actual (computed) value?, 0b1100expected value?) not run109 aobname? = bitOr(a, b)value or expression? # variable definition110 self.assertEqual(aobactual (computed) value?, 0b11111expected value?) not run111 axbname? = bitXor(a, b)value or expression? # variable definition112 self.assertEqual(axbactual (computed) value?, 0b10011expected value?) not run113 notaname? = bitNot(a)value or expression? # variable definition114 self.assertEqual(notaactual (computed) value?, -14expected value?) not run115 aLname? = bitShiftL(a, 2)value or expression? # variable definition116 self.assertEqual(aLactual (computed) value?, 0b110100expected value?) not run117 self.assertEqual(bitShiftR(a, 2)actual (computed) value?, 0b11expected value?) not run118 # end test
+[TestClass] class Test_bitwise
[TestMethod] static void test_bitwisetest_name?() { 119 var aname? = 13value or expression?;120 Assert.AreEqual(0xdexpected value?, aactual (computed) value?); not run121 Assert.AreEqual(0b1101expected value?, aactual (computed) value?); not run122 Assert.AreEqual("1101"expected value?, a.asBinary()actual (computed) value?); not run123 var bname? = 30value or expression?;124 Assert.AreEqual(0b11110expected value?, bactual (computed) value?); not run125 Assert.AreEqual(0b1100expected value?, bitAnd(a, b)actual (computed) value?); not run126 var aobname? = bitOr(a, b)value or expression?;127 Assert.AreEqual(0b11111expected value?, aobactual (computed) value?); not run128 var axbname? = bitXor(a, b)value or expression?;129 Assert.AreEqual(0b10011expected value?, axbactual (computed) value?); not run130 var notaname? = bitNot(a)value or expression?;131 Assert.AreEqual(-14expected value?, notaactual (computed) value?); not run132 var aLname? = bitShiftL(a, 2)value or expression?;133 Assert.AreEqual(0b110100expected value?, aLactual (computed) value?); not run134 Assert.AreEqual(0b11expected value?, bitShiftR(a, 2)actual (computed) value?); not run135 }} // end test
+<TestClass Class Test_bitwise
 <TestMethod> Sub test_bitwisetest_name?() 136 Dim aname? = 13value or expression? ' variable definition137 Assert.AreEqual(&Hdexpected value?, aactual (computed) value?) not run138 Assert.AreEqual(&B1101expected value?, aactual (computed) value?) not run139 Assert.AreEqual("1101"expected value?, a.asBinary()actual (computed) value?) not run140 Dim bname? = 30value or expression? ' variable definition141 Assert.AreEqual(&B11110expected value?, bactual (computed) value?) not run142 Assert.AreEqual(&B1100expected value?, bitAnd(a, b)actual (computed) value?) not run143 Dim aobname? = bitOr(a, b)value or expression? ' variable definition144 Assert.AreEqual(&B11111expected value?, aobactual (computed) value?) not run145 Dim axbname? = bitXor(a, b)value or expression? ' variable definition146 Assert.AreEqual(&B10011expected value?, axbactual (computed) value?) not run147 Dim notaname? = bitNot(a)value or expression? ' variable definition148 Assert.AreEqual(-14expected value?, notaactual (computed) value?) not run149 Dim aLname? = bitShiftL(a, 2)value or expression? ' variable definition150 Assert.AreEqual(&B110100expected value?, aLactual (computed) value?) not run151 Assert.AreEqual(&B11expected value?, bitShiftR(a, 2)actual (computed) value?) not run152  End Sub
End Class
+class Test_bitwise {
@Test static void test_bitwisetest_name?() { 153 var aname? = 13value or expression?;154 assertEquals(0xdexpected value?, aactual (computed) value?); not run155 assertEquals(0b1101expected value?, aactual (computed) value?); not run156 assertEquals("1101"expected value?, a.asBinary()actual (computed) value?); not run157 var bname? = 30value or expression?;158 assertEquals(0b11110expected value?, bactual (computed) value?); not run159 assertEquals(0b1100expected value?, bitAnd(a, b)actual (computed) value?); not run160 var aobname? = bitOr(a, b)value or expression?;161 assertEquals(0b11111expected value?, aobactual (computed) value?); not run162 var axbname? = bitXor(a, b)value or expression?;163 assertEquals(0b10011expected value?, axbactual (computed) value?); not run164 var notaname? = bitNot(a)value or expression?;165 assertEquals(-14expected value?, notaactual (computed) value?); not run166 var aLname? = bitShiftL(a, 2)value or expression?;167 assertEquals(0b110100expected value?, aLactual (computed) value?); not run168 assertEquals(0b11expected value?, bitShiftR(a, 2)actual (computed) value?); not run169 }} // end test

The result of bitNot(aaaaa) being -14-14-14-14-14 , when a is 1313131313, might be a surprise. But this is because the bitwise functions assume that the arguments are represented as 32-bit signed binary integers. So 13 is represented as
0000000000000000000000000000110100000000000000000000000000001101000000000000000000000000000011010000000000000000000000000000110100000000000000000000000000001101, and applying bitNot gives
1111111111111111111111111111001011111111111111111111111111110010111111111111111111111111111100101111111111111111111111111111001011111111111111111111111111110010which is the value -14-14-14-14-14in signed two's complement format,
the left-most bit being the sign (00000 positive, 11111 negative).

RegExp functions

Elan's regular expressions are modelled on those of JavaScript, including the syntax for literal regular expressions. See, for example this Guide to Regular Expressions .

More functions for using regular expressions will be added in a future release of Elan. For now:

The method matchesRegExp is applied to a StringstrstringStringString using dot syntax and requires a RegExpRegExpRegExpRegExpRegExp parameter specified as a literal or as variable. It returns a BooleanboolboolBooleanboolean. For example:

+test test_matchesRegExptest_name? 170 variable s1name? set to "hello"value or expression?171 variable s2name? set to "World"value or expression?172 variable rname? set to /^[a-z]*$/value or expression?173 assert s1.matchesRegExp(r)actual (computed) value? evaluates to trueexpected value? not run174 assert s2.matchesRegExp(r)actual (computed) value? evaluates to falseexpected value? not run175 end test
+class Test_matchesRegExp(unittest.TestCase):
 def test_matchesRegExptest_name?(self) -> None: 176 s1name? = "hello"value or expression? # variable definition177 s2name? = "World"value or expression? # variable definition178 rname? = /^[a-z]*$/value or expression? # variable definition179 self.assertEqual(s1.matchesRegExp(r)actual (computed) value?, Trueexpected value?) not run180 self.assertEqual(s2.matchesRegExp(r)actual (computed) value?, Falseexpected value?) not run181 # end test
+[TestClass] class Test_matchesRegExp
[TestMethod] static void test_matchesRegExptest_name?() { 182 var s1name? = "hello"value or expression?;183 var s2name? = "World"value or expression?;184 var rname? = /^[a-z]*$/value or expression?;185 Assert.AreEqual(trueexpected value?, s1.matchesRegExp(r)actual (computed) value?); not run186 Assert.AreEqual(falseexpected value?, s2.matchesRegExp(r)actual (computed) value?); not run187 }} // end test
+<TestClass Class Test_matchesRegExp
 <TestMethod> Sub test_matchesRegExptest_name?() 188 Dim s1name? = "hello"value or expression? ' variable definition189 Dim s2name? = "World"value or expression? ' variable definition190 Dim rname? = /^(a-z)*$/value or expression? ' variable definition191 Assert.AreEqual(Trueexpected value?, s1.matchesRegExp(r)actual (computed) value?) not run192 Assert.AreEqual(Falseexpected value?, s2.matchesRegExp(r)actual (computed) value?) not run193  End Sub
End Class
+class Test_matchesRegExp {
@Test static void test_matchesRegExptest_name?() { 194 var s1name? = "hello"value or expression?;195 var s2name? = "World"value or expression?;196 var rname? = /^[a-z]*$/value or expression?;197 assertEquals(trueexpected value?, s1.matchesRegExp(r)actual (computed) value?); not run198 assertEquals(falseexpected value?, s2.matchesRegExp(r)actual (computed) value?); not run199 }} // end test

You can convert a valid string without /..//..//..//..//../ delimiters to a RegExpRegExpRegExpRegExpRegExp using function asRegExp:

+test test_matchesRegExptest_name? 200 variable s1name? set to "hello"value or expression?201 variable s2name? set to "World"value or expression?202 variable rname? set to "^[a-z]*$".asRegExp()value or expression?203 assert s1.matchesRegExp(r)actual (computed) value? evaluates to trueexpected value? not run204 assert s2.matchesRegExp(r)actual (computed) value? evaluates to falseexpected value? not run205 end test
+class Test_matchesRegExp(unittest.TestCase):
 def test_matchesRegExptest_name?(self) -> None: 206 s1name? = "hello"value or expression? # variable definition207 s2name? = "World"value or expression? # variable definition208 rname? = "^[a-z]*$".asRegExp()value or expression? # variable definition209 self.assertEqual(s1.matchesRegExp(r)actual (computed) value?, Trueexpected value?) not run210 self.assertEqual(s2.matchesRegExp(r)actual (computed) value?, Falseexpected value?) not run211 # end test
+[TestClass] class Test_matchesRegExp
[TestMethod] static void test_matchesRegExptest_name?() { 212 var s1name? = "hello"value or expression?;213 var s2name? = "World"value or expression?;214 var rname? = "^[a-z]*$".asRegExp()value or expression?;215 Assert.AreEqual(trueexpected value?, s1.matchesRegExp(r)actual (computed) value?); not run216 Assert.AreEqual(falseexpected value?, s2.matchesRegExp(r)actual (computed) value?); not run217 }} // end test
+<TestClass Class Test_matchesRegExp
 <TestMethod> Sub test_matchesRegExptest_name?() 218 Dim s1name? = "hello"value or expression? ' variable definition219 Dim s2name? = "World"value or expression? ' variable definition220 Dim rname? = "^(a-z)*$".asRegExp()value or expression? ' variable definition221 Assert.AreEqual(Trueexpected value?, s1.matchesRegExp(r)actual (computed) value?) not run222 Assert.AreEqual(Falseexpected value?, s2.matchesRegExp(r)actual (computed) value?) not run223  End Sub
End Class
+class Test_matchesRegExp {
@Test static void test_matchesRegExptest_name?() { 224 var s1name? = "hello"value or expression?;225 var s2name? = "World"value or expression?;226 var rname? = "^[a-z]*$".asRegExp()value or expression?;227 assertEquals(trueexpected value?, s1.matchesRegExp(r)actual (computed) value?); not run228 assertEquals(falseexpected value?, s2.matchesRegExp(r)actual (computed) value?); not run229 }} // end test

Although it is recommended that literal regular expressions are written with /..//..//..//..//../ delimiters, the ability to convert a stringstringstringstringstring allows you to input a regular expression into a running program.

System methods

System methods appear to work like functions, because:

They are not, however, pure functions because:

Because of these properties, system methods may be used only within the main routine or a procedure. They may not be used inside a function that you have defined, because to do so would prevent the function from being pure.

You cannot write a system method yourself.

Input/output

Clock

Method clock returns the current value of the system clock. This can be useful for measuring elapsed time by comparing the values returned by two calls.

system
method		 argument
types		 return
types		 returns
clock (none) IntintintIntegerint the current value (in milliseconds) of the system clock

Random methods

Methods random and randint cannot be used in a function because of their dependence on external factors, i.e. they are subject to side effects.
To obtain random numbers within a function, use a variable of type RandomRandomRandomRandomRandom .
system
method		 argument
types		 return
types		 returns
random (none) FloatfloatdoubleDoubledouble a random number in the range [0..1]
randint IntintintIntegerint, IntintintIntegerint IntintintIntegerint a random number in the (inclusive) range between the two arguments

Higher-order Functions (HoFs)

A higher-order Function (HoF) is one that takes in a reference to another function as a parameter. (Strictly speaking, a HoF may also be a function that returns another function, but Elan does not currently support that pattern.)

Standard HoFs

The standard library contains several HoFs that are widely recognised and used within functional programming, namely:
filter , map and reduce ,
and also provides:
sumBy , maxBy , minBy and orderBy .

You cannot define your own Higher-order Functions.

Library functions that process Lists

These dot methods may be called on any ListlistListListList or StringstrstringStringString. As Higher-order Functions they take either a lambdalambdalambdalambdalambda or a function reference as one of their arguments.

These are not yet fully documented but, for readers familiar with HoFs from another programming language, some examples are shown below.

filter

You give a ListlistListListList to the Higher-order Function filter in order to return a new ListlistListListList containing a subset of items. The subset is chosen by a lambdalambdalambdalambdalambda that tests ListlistListListList item values and returns a Boolean to specify filtering in or out.

Example using filter

   ● Example from demo program pathfinder in which filter applies the lambdalambdalambdalambdalambda to the nodesnodesnodesnodesnodes (of class NodeNodeNodeNodeNode) to find one that contains ppppp (of class PointPointPointPointPoint):

+function getNodeForname?(p as Pointparameter definitions?) returns NodeType? 230 variable matchesname? set to this.nodes.filter(lambda n as Node => n.point.equals(p))value or expression?231 return if_(matches.length() is 1, matches.head(), emptyNode())value or expression?232 end function
+def getNodeForname?(p: Pointparameter definitions?) -> NodeType?: # function233 matchesname? = self.nodes.filter(lambda n: Node: n.point.equals(p))value or expression? # variable definition234 return if_(matches.length() == 1, matches.head(), emptyNode())value or expression?235 # end function
+static NodeType? getNodeForname?(Point pparameter definitions?) { // function236 var matchesname? = this.nodes.filter(Node n => n.point.equals(p))value or expression?;237 return if_(matches.length() == 1, matches.head(), emptyNode())value or expression?;238 } // end function
+Function getNodeForname?(p As Pointparameter definitions?) As NodeType? 239 Dim matchesname? = Me.nodes.filter(Function (n As Node) n.point.equals(p))value or expression? ' variable definition240 Return if_(matches.length() = 1, matches.head(), emptyNode())value or expression?241 End Function
+static NodeType? getNodeForname?(Point pparameter definitions?) { // function242 var matchesname? = this.nodes.filter((Node n) -> n.point.equals(p))value or expression?;243 return if_(matches.length() == 1, matches.head(), emptyNode())value or expression?;244 } // end function

map

The function map is used to apply a function to every item in a ListlistListListList, and return a new ListlistListListList. The function to be applied is usually specified as a lambdalambdalambdalambdalambda having a single argument of the type of the ListlistListListList's items, as in these examples:

Examples using map

   ● To cube each integer value in a ListlistListListList:

+main 245 variable liname? set to [1, 2, 3, 4, 5]value or expression?246 print(li.map(lambda n as Int => pow(n, 3))value or expression?)247 end main
+def main() -> None: 248 liname? = [1, 2, 3, 4, 5]value or expression? # variable definition249 print(li.map(lambda n: int: pow(n, 3))value or expression?)250 # end main
+static void main() { 251 var liname? = new [] {1, 2, 3, 4, 5}value or expression?;252 Console.WriteLine(li.map(int n => pow(n, 3))value or expression?); // print statement253 } // end main
+Sub main() 254 Dim liname? = {1, 2, 3, 4, 5}value or expression? ' variable definition255 Console.WriteLine(li.map(Function (n As Integer) pow(n, 3))value or expression?) ' print statement256 End Sub
+static void main() { 257 var liname? = list(1, 2, 3, 4, 5)value or expression?;258 System.out.println(li.map((int n) -> pow(n, 3))value or expression?); // print statement259 } // end main


⟶

[1, 8, 27, 125][1, 8, 27, 125]new [] {1, 8, 27, 125}{1, 8, 27, 125}list(1, 8, 27, 125)

   ● To change each string in a ListlistListListList to upper case:

+main 260 variable namesname? set to ["Tom", "Dick", "Harriet"]value or expression?261 print(names.map(lambda s as String => s.upperCase())value or expression?)262 end main
+def main() -> None: 263 namesname? = ["Tom", "Dick", "Harriet"]value or expression? # variable definition264 print(names.map(lambda s: str: s.upperCase())value or expression?)265 # end main
+static void main() { 266 var namesname? = new [] {"Tom", "Dick", "Harriet"}value or expression?;267 Console.WriteLine(names.map(string s => s.upperCase())value or expression?); // print statement268 } // end main
+Sub main() 269 Dim namesname? = {"Tom", "Dick", "Harriet"}value or expression? ' variable definition270 Console.WriteLine(names.map(Function (s As String) s.upperCase())value or expression?) ' print statement271 End Sub
+static void main() { 272 var namesname? = list("Tom", "Dick", "Harriet")value or expression?;273 System.out.println(names.map((String s) -> s.upperCase())value or expression?); // print statement274 } // end main


⟶

[TOM, DICK, HARRIET]

   ● To reverse each string in the ListlistListListList of names using the function reverse:

+main 1 print(names.map(lambda s as String => reverse(s))value or expression?)2 end main +function reversename?(s as Stringparameter definitions?) returns StringType? 3 variable sReturnname? set to ""value or expression?4 +for chitem? in ssource? 5 assign sReturnvariableName? to ch + sReturnvalue or expression?6 end for return sReturnvalue or expression?7 end function
+def main() -> None: 1 print(names.map(lambda s: str: reverse(s))value or expression?)2 # end main +def reversename?(s: strparameter definitions?) -> strType?: # function3 sReturnname? = ""value or expression? # variable definition4 +for chitem? in ssource?: 5 sReturnvariableName? = ch + sReturnvalue or expression? # assignment6 # end for return sReturnvalue or expression?7 # end function main()
+static void main() { 1 Console.WriteLine(names.map(string s => reverse(s))value or expression?); // print statement2 } // end main +static stringType? reversename?(string sparameter definitions?) { // function3 var sReturnname? = ""value or expression?;4 +foreach (var chitem? in ssource?) { 5 sReturnvariableName? = ch + sReturnvalue or expression?; // assignment6 } // end foreach return sReturnvalue or expression?;7 } // end function
+Sub main() 1 Console.WriteLine(names.map(Function (s As String) reverse(s))value or expression?) ' print statement2 End Sub +Function reversename?(s As Stringparameter definitions?) As StringType? 3 Dim sReturnname? = ""value or expression? ' variable definition4 +For Each chitem? In ssource? 5 sReturnvariableName? = ch + sReturnvalue or expression? ' assignment6 Next ch Return sReturnvalue or expression?7 End Function
public class Global {

+static void main() { 1 System.out.println(names.map((String s) -> reverse(s))value or expression?); // print statement2 } // end main +static StringType? reversename?(String sparameter definitions?) { // function3 var sReturnname? = ""value or expression?;4 +foreach (var chitem? in ssource?) { 5 sReturnvariableName? = ch + sReturnvalue or expression?; // assignment6 } // end foreach return sReturnvalue or expression?;7 } // end function
} // end Global
⟶
[moT, kciD, teirraH]

   ● And this example from demo program maze-generator:

variable nname? set to p.neighbouringPoints().map(lambda p as Point => getValue(p, g))value or expression?8
nname? = p.neighbouringPoints().map(lambda p: Point: getValue(p, g))value or expression? # variable definition9
var nname? = p.neighbouringPoints().map(Point p => getValue(p, g))value or expression?;10
Dim nname? = p.neighbouringPoints().map(Function (p As Point) getValue(p, g))value or expression? ' variable definition11
var nname? = p.neighbouringPoints().map((Point p) -> getValue(p, g))value or expression?;12

reduce

The function reduce is used to combine the items in a ListlistListListList in some way to produce a single result. This result may be of the same type as the items in the ListlistListListList, for example to:

The result may, however, be of a different type than the items in the ListlistListListList, and may even be a data structure, for example to:

Method reduce requires two arguments:

  1. the initial, or 'seed', value, of the type that you wish to be returned by the function specified in the second argument. For example, if you were finding the sum of a ListlistListListList of type FloatfloatdoubleDoubledouble, the initial seed value would typically be 0.00.00.00.00.0. If you were creating a dictionary of words, the initial seed value would be an empty dictionary of the correct key and value types.
  2. the function or lambdalambdalambdalambdalambda to be applied, which itself requires two arguments:
    1. the accumulating named value, which is therefore of the same type as the initial seed value, (This will be the return value of the function or lambdalambdalambdalambdalambda).
    2. the item to which the function is applied, which is therefore of the same type as the items in the input ListlistListListList.

In other words, the specified function or lambdalambdalambdalambdalambda is applied to each item of the input ListlistListListList in turn, in each case passing in the current value of the result. The function makes use of both to generate a new value for the result, replacing the current one for application to the next item. This is best understood by looking at the examples.

Examples using reduce

   ● To reduce the floating point values in a ListlistListListList to their sum:

+main 13 variable nname? set to [0.1, 2, 2.5, 0.3, 5.75, 0.29]value or expression?14 print(n.reduce(0.0, lambda sum as Float, m as Float => (sum + m).round(2))value or expression?)15 end main
+def main() -> None: 16 nname? = [0.1, 2, 2.5, 0.3, 5.75, 0.29]value or expression? # variable definition17 print(n.reduce(0.0, lambda sum: float, m: float: (sum + m).round(2))value or expression?)18 # end main
+static void main() { 19 var nname? = new [] {0.1, 2, 2.5, 0.3, 5.75, 0.29}value or expression?;20 Console.WriteLine(n.reduce(0.0, double sum, double m => (sum + m).round(2))value or expression?); // print statement21 } // end main
+Sub main() 22 Dim nname? = {0.1, 2, 2.5, 0.3, 5.75, 0.29}value or expression? ' variable definition23 Console.WriteLine(n.reduce(0.0, Function (sum As Double, m As Double) (sum + m).round(2))value or expression?) ' print statement24 End Sub
+static void main() { 25 var nname? = list(0.1, 2, 2.5, 0.3, 5.75, 0.29)value or expression?;26 System.out.println(n.reduce(0.0, (double sum, double m) -> (sum + m).round(2))value or expression?); // print statement27 } // end main


⟶

10.9410.9410.9410.9410.94
   Notes

   ● To reverse the order of items in a ListlistListListList:

+main 28 variable nname? set to [2, 3, 5, 7, 11, 13]value or expression?29 variable nRname? set to new List<of Int>()value or expression?30 variable eLname? set to new List<of Int>()value or expression?31 print(n.reduce(eL, lambda nR as List<of Int>, m as Int => nR.withPrepend(m))value or expression?)32 end main
+def main() -> None: 33 nname? = [2, 3, 5, 7, 11, 13]value or expression? # variable definition34 nRname? = list[int]()value or expression? # variable definition35 eLname? = list[int]()value or expression? # variable definition36 print(n.reduce(eL, lambda nR: list[int], m: int: nR.withPrepend(m))value or expression?)37 # end main
+static void main() { 38 var nname? = new [] {2, 3, 5, 7, 11, 13}value or expression?;39 var nRname? = new List<int>()value or expression?;40 var eLname? = new List<int>()value or expression?;41 Console.WriteLine(n.reduce(eL, List<int> nR, int m => nR.withPrepend(m))value or expression?); // print statement42 } // end main
+Sub main() 43 Dim nname? = {2, 3, 5, 7, 11, 13}value or expression? ' variable definition44 Dim nRname? = New List(Of Integer)()value or expression? ' variable definition45 Dim eLname? = New List(Of Integer)()value or expression? ' variable definition46 Console.WriteLine(n.reduce(eL, Function (nR As List(Of Integer), m As Integer) nR.withPrepend(m))value or expression?) ' print statement47 End Sub
+static void main() { 48 var nname? = list(2, 3, 5, 7, 11, 13)value or expression?;49 var nRname? = new List<int>()value or expression?;50 var eLname? = new List<int>()value or expression?;51 System.out.println(n.reduce(eL, (List<int> nR, int m) -> nR.withPrepend(m))value or expression?); // print statement52 } // end main




⟶



[13, 11, 7, 5, 3, 2][13, 11, 7, 5, 3, 2]new [] {13, 11, 7, 5, 3, 2}{13, 11, 7, 5, 3, 2}list(13, 11, 7, 5, 3, 2)

   ● To reverse the order of the words in a StringstrstringStringString, use reduce on a ListlistListListList of words (created by split and then reassembled by join):

+main 53 variable sname? set to "'Twas brillig and the slithy toves"value or expression?54 variable sRname? set to ""value or expression?55 variable eLname? set to new List<of String>()value or expression?56 assign sRvariableName? to s.split(" ").reduce(eL, lambda sR as List<of String>, word as String => sR.withPrepend(word)).join(" ")value or expression?57 print(sRvalue or expression?)58 end main
+def main() -> None: 59 sname? = "'Twas brillig and the slithy toves"value or expression? # variable definition60 sRname? = ""value or expression? # variable definition61 eLname? = list[str]()value or expression? # variable definition62 sRvariableName? = s.split(" ").reduce(eL, lambda sR: list[str], word: str: sR.withPrepend(word)).join(" ")value or expression? # assignment63 print(sRvalue or expression?)64 # end main
+static void main() { 65 var sname? = "'Twas brillig and the slithy toves"value or expression?;66 var sRname? = ""value or expression?;67 var eLname? = new List<string>()value or expression?;68 sRvariableName? = s.split(" ").reduce(eL, List<string> sR, string word => sR.withPrepend(word)).join(" ")value or expression?; // assignment69 Console.WriteLine(sRvalue or expression?); // print statement70 } // end main
+Sub main() 71 Dim sname? = "'Twas brillig and the slithy toves"value or expression? ' variable definition72 Dim sRname? = ""value or expression? ' variable definition73 Dim eLname? = New List(Of String)()value or expression? ' variable definition74 sRvariableName? = s.split(" ").reduce(eL, Function (sR As List(Of String), word As String) sR.withPrepend(word)).join(" ")value or expression? ' assignment75 Console.WriteLine(sRvalue or expression?) ' print statement76 End Sub
+static void main() { 77 var sname? = "'Twas brillig and the slithy toves"value or expression?;78 var sRname? = ""value or expression?;79 var eLname? = new List<String>()value or expression?;80 sRvariableName? = s.split(" ").reduce(eL, (List<String> sR, String word) -> sR.withPrepend(word)).join(" ")value or expression?; // assignment81 System.out.println(sRvalue or expression?); // print statement82 } // end main





⟶




"toves slithy the and brillig 'Twas""toves slithy the and brillig 'Twas""toves slithy the and brillig 'Twas""toves slithy the and brillig 'Twas""toves slithy the and brillig 'Twas"
   Note

maxBy and minBy

maxBy and minBy are dot methods on a ListlistListListList. They take a function as an argument, and return the ListlistListListList item corresponding to the maximum or minimum of the values returned by the function.

For simply finding the maximum or minimum value in a ListlistListListList, you can use max , min .

Examples using maxBy and minBy

   ● To find in a ListlistListListList the integer that has the highest last digit:

+main 83 variable aname? set to [33, 4, 0, 92, 89, 55, 102]value or expression?84 print(a.maxBy(lambda x as Int => x mod 10)value or expression?)85 end main
+def main() -> None: 86 aname? = [33, 4, 0, 92, 89, 55, 102]value or expression? # variable definition87 print(a.maxBy(lambda x: int: x % 10)value or expression?)88 # end main
+static void main() { 89 var aname? = new [] {33, 4, 0, 92, 89, 55, 102}value or expression?;90 Console.WriteLine(a.maxBy(int x => x % 10)value or expression?); // print statement91 } // end main
+Sub main() 92 Dim aname? = {33, 4, 0, 92, 89, 55, 102}value or expression? ' variable definition93 Console.WriteLine(a.maxBy(Function (x As Integer) x Mod 10)value or expression?) ' print statement94 End Sub
+static void main() { 95 var aname? = list(33, 4, 0, 92, 89, 55, 102)value or expression?;96 System.out.println(a.maxBy((int x) -> x % 10)value or expression?); // print statement97 } // end main


⟶

8989898989

   ● To find in a ListlistListListList the the shortest string:

+main 98 variable fruitname? set to ["apple", "orange", "pear"]value or expression?99 print(fruit.minBy(lambda x as String => x.length())value or expression?)100 end main
+def main() -> None: 101 fruitname? = ["apple", "orange", "pear"]value or expression? # variable definition102 print(fruit.minBy(lambda x: str: x.length())value or expression?)103 # end main
+static void main() { 104 var fruitname? = new [] {"apple", "orange", "pear"}value or expression?;105 Console.WriteLine(fruit.minBy(string x => x.length())value or expression?); // print statement106 } // end main
+Sub main() 107 Dim fruitname? = {"apple", "orange", "pear"}value or expression? ' variable definition108 Console.WriteLine(fruit.minBy(Function (x As String) x.length())value or expression?) ' print statement109 End Sub
+static void main() { 110 var fruitname? = list("apple", "orange", "pear")value or expression?;111 System.out.println(fruit.minBy((String x) -> x.length())value or expression?); // print statement112 } // end main


⟶

pearpearpearpearpear

sumBy

sumBy calculates the numerical sum of the items generated by the specified lambda (or named function) which must return a floating point value. This does not mean that the ListlistListListList on which sumBy has to be of type List<of Float>list[float]List<double>List(Of Double)List<double>. However, the lambda must process each element in a way that returns a FloatfloatdoubleDoubledouble.

Examples using sumBy

This example is taken from the Best Fit demo (offered when the paradigm is set to functional) to calculate the various 'sigma' (sum of) terms needed to estimate the best fit line:

+function bestFitLinename?(points as List<of Point>parameter definitions?) returns (Float, Float)Type? 113 let sumXname? be points.sumBy(lambda p as Point => p.x)value or expression?114 let sumXsqname? be points.sumBy(lambda p as Point => p.x*p.x)value or expression?115 let sumYname? be points.sumBy(lambda p as Point => p.y)value or expression?116 let sumXYname? be points.sumBy(lambda p as Point => p.x*p.y)value or expression?117 let nname? be points.length()value or expression?118 let aname? be (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression?119 let bname? be (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression?120 return (a, b)value or expression?121 end function
+def bestFitLinename?(points: list[Point]parameter definitions?) -> tuple[float, float]Type?: # function122 sumXname? = points.sumBy(lambda p: Point: p.x)value or expression? # let123 sumXsqname? = points.sumBy(lambda p: Point: p.x*p.x)value or expression? # let124 sumYname? = points.sumBy(lambda p: Point: p.y)value or expression? # let125 sumXYname? = points.sumBy(lambda p: Point: p.x*p.y)value or expression? # let126 nname? = points.length()value or expression? # let127 aname? = (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression? # let128 bname? = (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression? # let129 return (a, b)value or expression?130 # end function
+static (double, double)Type? bestFitLinename?(List<Point> pointsparameter definitions?) { // function131 var sumXname? = points.sumBy(Point p => p.x)value or expression?; // let132 var sumXsqname? = points.sumBy(Point p => p.x*p.x)value or expression?; // let133 var sumYname? = points.sumBy(Point p => p.y)value or expression?; // let134 var sumXYname? = points.sumBy(Point p => p.x*p.y)value or expression?; // let135 var nname? = points.length()value or expression?; // let136 var aname? = (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression?; // let137 var bname? = (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression?; // let138 return (a, b)value or expression?;139 } // end function
+Function bestFitLinename?(points As List(Of Point)parameter definitions?) As (Double, Double)Type? 140 Dim sumXname? = points.sumBy(Function (p As Point) p.x)value or expression? ' let141 Dim sumXsqname? = points.sumBy(Function (p As Point) p.x*p.x)value or expression? ' let142 Dim sumYname? = points.sumBy(Function (p As Point) p.y)value or expression? ' let143 Dim sumXYname? = points.sumBy(Function (p As Point) p.x*p.y)value or expression? ' let144 Dim nname? = points.length()value or expression? ' let145 Dim aname? = (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression? ' let146 Dim bname? = (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression? ' let147 Return (a, b)value or expression?148 End Function
+static (double, double)Type? bestFitLinename?(List<Point> pointsparameter definitions?) { // function149 var sumXname? = points.sumBy((Point p) -> p.x)value or expression?; // let150 var sumXsqname? = points.sumBy((Point p) -> p.x*p.x)value or expression?; // let151 var sumYname? = points.sumBy((Point p) -> p.y)value or expression?; // let152 var sumXYname? = points.sumBy((Point p) -> p.x*p.y)value or expression?; // let153 var nname? = points.length()value or expression?; // let154 var aname? = (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression?; // let155 var bname? = (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression?; // let156 return (a, b)value or expression?;157 } // end function

orderBy

orderBy takes a lambdalambdalambdalambdalambda that has two arguments of the same type as that of the ListlistListListList items to be re-ordered and compares them, returning a Boolean value that distinguishes between less than (or greater than) for numerics and before (or after) for strings.

Examples using orderBy

   ● To reorder integers in a ListlistListListList, using > for ascending (you would use < for descending):

+main 158 variable numbersname? set to [27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23]value or expression?159 variable orderedname? set to numbers.orderBy(lambda x as Int, y as Int => x > y)value or expression?160 print(orderedvalue or expression?)161 end main
+def main() -> None: 162 numbersname? = [27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23]value or expression? # variable definition163 orderedname? = numbers.orderBy(lambda x: int, y: int: x > y)value or expression? # variable definition164 print(orderedvalue or expression?)165 # end main
+static void main() { 166 var numbersname? = new [] {27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23}value or expression?;167 var orderedname? = numbers.orderBy(int x, int y => x > y)value or expression?;168 Console.WriteLine(orderedvalue or expression?); // print statement169 } // end main
+Sub main() 170 Dim numbersname? = {27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23}value or expression? ' variable definition171 Dim orderedname? = numbers.orderBy(Function (x As Integer, y As Integer) x > y)value or expression? ' variable definition172 Console.WriteLine(orderedvalue or expression?) ' print statement173 End Sub
+static void main() { 174 var numbersname? = list(27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23)value or expression?;175 var orderedname? = numbers.orderBy((int x, int y) -> x > y)value or expression?;176 System.out.println(orderedvalue or expression?); // print statement177 } // end main

⟶
[2, 3, 5, 7, 11, 13, 19, 23, 23, 27, 31, 37][2, 3, 5, 7, 11, 13, 19, 23, 23, 27, 31, 37]new [] {2, 3, 5, 7, 11, 13, 19, 23, 23, 27, 31, 37}{2, 3, 5, 7, 11, 13, 19, 23, 23, 27, 31, 37}list(2, 3, 5, 7, 11, 13, 19, 23, 23, 27, 31, 37)

   ● To reorder strings in a ListlistListListList, using method isBefore for descending (you would use isAfter for ascending):

+main 178 variable namesname? set to ["Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul"]value or expression?179 print(names.orderBy(lambda x as String, y as String => x.isBefore(y))value or expression?)180 end main
+def main() -> None: 181 namesname? = ["Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul"]value or expression? # variable definition182 print(names.orderBy(lambda x: str, y: str: x.isBefore(y))value or expression?)183 # end main
+static void main() { 184 var namesname? = new [] {"Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul"}value or expression?;185 Console.WriteLine(names.orderBy(string x, string y => x.isBefore(y))value or expression?); // print statement186 } // end main
+Sub main() 187 Dim namesname? = {"Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul"}value or expression? ' variable definition188 Console.WriteLine(names.orderBy(Function (x As String, y As String) x.isBefore(y))value or expression?) ' print statement189 End Sub
+static void main() { 190 var namesname? = list("Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul")value or expression?;191 System.out.println(names.orderBy((String x, String y) -> x.isBefore(y))value or expression?); // print statement192 } // end main



⟶


["Zelda", "Simon", "Pauline", "Paul", "Lance", "Jason", "Edith", "Alice"]["Zelda", "Simon", "Pauline", "Paul", "Lance", "Jason", "Edith", "Alice"]new [] {"Zelda", "Simon", "Pauline", "Paul", "Lance", "Jason", "Edith", "Alice"}{"Zelda", "Simon", "Pauline", "Paul", "Lance", "Jason", "Edith", "Alice"}list("Zelda", "Simon", "Pauline", "Paul", "Lance", "Jason", "Edith", "Alice")

Passing a function as a reference

To use a Higher-order Function (HoF), you have to pass in a reference to a function. This can be either a lambdalambdalambdalambdalambda or the name of a function. It is also possible to use references to functions not in the context of HoFs.

On most occasions when you write the name of an existing function elsewhere in code your intent is to evaluate the function and, to do so, you write the name of the function followed by round brackets containing such arguments as are required by the function. When passing a function, its name is not followed by round brackets (or arguments), as in this example:

+class PupilName? inheritance?1 +constructor(parameter definitions?) 2 new code end constructor property mathsPercentname? as IntType?3 +function toStringname?(parameter definitions?) returns StringType? 4 return "undefined"value or expression?5 end function end class +main 6 variable allPupilsname? set to new List<of Pupil>()value or expression?7 variable passesname? set to allPupils.filter(passedMathsTest)value or expression?8 end main +function passedMathsTestname?(p as Pupilparameter definitions?) returns BooleanType? 9 return p.mathsPercent > 35value or expression?10 end function
+class PupilName? inheritance?: # concrete class1 +def __init__(self: Pupil) -> None: 2 new code # end constructor mathsPercentname?: intType? # property3 +def toStringname?(self: Pupil) -> strType?: # function method4 return "undefined"value or expression?5 # end function method # end class +def main() -> None: 6 allPupilsname? = list[Pupil]()value or expression? # variable definition7 passesname? = allPupils.filter(passedMathsTest)value or expression? # variable definition8 # end main +def passedMathsTestname?(p: Pupilparameter definitions?) -> boolType?: # function9 return p.mathsPercent > 35value or expression?10 # end function main()
+class PupilName? inheritance? {1 +public Pupil(parameter definitions?) { 2 new code } // end constructor public intType? mathsPercentname? {get; private set;} // property3 +public stringType? toStringname?(parameter definitions?) { // function method4 return "undefined"value or expression?;5 } // end function method } // end class +static void main() { 6 var allPupilsname? = new List<Pupil>()value or expression?;7 var passesname? = allPupils.filter(passedMathsTest)value or expression?;8 } // end main +static boolType? passedMathsTestname?(Pupil pparameter definitions?) { // function9 return p.mathsPercent > 35value or expression?;10 } // end function
+Class PupilName? inheritance?1 +Sub New(parameter definitions?) 2 new code End Sub Property mathsPercentname? As IntegerType?3 +Function toStringname?(parameter definitions?) As StringType? 4 Return "undefined"value or expression?5 End Function End Class +Sub main() 6 Dim allPupilsname? = New List(Of Pupil)()value or expression? ' variable definition7 Dim passesname? = allPupils.filter(passedMathsTest)value or expression? ' variable definition8 End Sub +Function passedMathsTestname?(p As Pupilparameter definitions?) As BooleanType? 9 Return p.mathsPercent > 35value or expression?10 End Function
public class Global {

+class PupilName? inheritance? {1 +public Pupil(parameter definitions?) { 2 new code } // end constructor public intType? mathsPercentname?; // property3 +public StringType? toStringname?(parameter definitions?) { // function method4 return "undefined"value or expression?;5 } // end function method } // end class +static void main() { 6 var allPupilsname? = new List<Pupil>()value or expression?;7 var passesname? = allPupils.filter(passedMathsTest)value or expression?;8 } // end main +static booleanType? passedMathsTestname?(Pupil pparameter definitions?) { // function9 return p.mathsPercent > 35value or expression?;10 } // end function
} // end Global

System constants

System constants are unlike values that you define in your program constant , in that they are mutable named values, though it would be poor practice to change them.

String constants

These constants are of use when the characters { } and " are required within a string.

nametypevalue
openBraceopenBraceopenBraceopenBraceopenBrace StringstrstringStringString   {
closeBracecloseBracecloseBracecloseBracecloseBrace StringstrstringStringString   }
quotesquotesquotesquotesquotes StringstrstringStringString   "

Maths constant

nametypevalue
pipipipipi FloatfloatdoubleDoubledouble 𝜋 = 3.141592653589793..

Boolean constants

nametypevalue
trueTruetrueTruetrue BooleanboolboolBooleanboolean trueTruetrueTruetrue
falseFalsefalseFalsefalse BooleanboolboolBooleanboolean falseFalsefalseFalsefalse

Colour constants

colourdecimaldecimal
hexadecimal
nameinteger   R    G    B 0xrrggbb
blackblackblackblackblack ◼0   0    0    00x0000000x0000000x000000&H0000000x000000
whitewhitewhitewhitewhite ◼16777215 255  255  2550xffffff0xffffff0xffffff&Hffffff0xffffff
redredredredred ◼16711680 255    0    00xff00000xff00000xff0000&Hff00000xff0000
greengreengreengreengreen ◼32768  0  128    00x0080000x0080000x008000&H0080000x008000
blueblueblueblueblue ◼255   0    0  2550x0000ff0x0000ff0x0000ff&H0000ff0x0000ff
yellowyellowyellowyellowyellow◼16776960 255  255    00xffff000xffff000xffff00&Hffff000xffff00
brownbrownbrownbrownbrown ◼10824234 165   42   420xa52a2a0xa52a2a0xa52a2a&Ha52a2a0xa52a2a
greygreygreygreygrey ◼8421504 128  128  1280x8080800x8080800x808080&H8080800x808080
transparenttransparenttransparenttransparenttransparent ◻-1n/an/a

A colour is specified as an IntintintIntegerint value using one of these methods:

transparenttransparenttransparenttransparenttransparent is used only for filling vector graphics shapes.

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