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? 195 variable hname? set to ""value or expression?196 +if (n < 1)condition? then 197 assign hvariableName? to "0"value or expression?198 else199 variable mname? set to nvalue or expression?200 +while m > 0condition? 201 assign hvariableName? to hexDigit(m mod 16) + hvalue or expression?202 assign mvariableName? to divAsInt(m, 16)value or expression?203 end while end if return hvalue or expression?204 end function
+def hexname?(n: intparameter definitions?) -> strType?: # function205 hname? = ""value or expression? # variable definition206 +if (n < 1)condition?: 207 hvariableName? = "0"value or expression? # assignment208 else:209 mname? = nvalue or expression? # variable definition210 +while m > 0condition?: 211 hvariableName? = hexDigit(m % 16) + hvalue or expression? # assignment212 mvariableName? = divAsInt(m, 16)value or expression? # assignment213 # end while # end if return hvalue or expression?214 # end function
+static stringType? hexname?(int nparameter definitions?) { // function215 var hname? = ""value or expression?;216 +if ((n < 1)condition?) { 217 hvariableName? = "0"value or expression?; // assignment218 } else {219 var mname? = nvalue or expression?;220 +while (m > 0condition?) { 221 hvariableName? = hexDigit(m % 16) + hvalue or expression?; // assignment222 mvariableName? = divAsInt(m, 16)value or expression?; // assignment223 } // end while } // end if return hvalue or expression?;224 } // end function
+Function hexname?(n As Integerparameter definitions?) As StringType? 225 Dim hname? = ""value or expression? ' variable definition226 +If (n < 1)condition? Then 227 hvariableName? = "0"value or expression? ' assignment228 Else229 Dim mname? = nvalue or expression? ' variable definition230 +While m > 0condition? 231 hvariableName? = hexDigit(m Mod 16) + hvalue or expression? ' assignment232 mvariableName? = divAsInt(m, 16)value or expression? ' assignment233 End While End If Return hvalue or expression?234 End Function
+static StringType? hexname?(int nparameter definitions?) { // function235 var hname? = ""value or expression?;236 +if ((n < 1)condition?) { 237 hvariableName? = "0"value or expression?; // assignment238 } else {239 var mname? = nvalue or expression?;240 +while (m > 0condition?) { 241 hvariableName? = hexDigit(m % 16) + hvalue or expression?; // assignment242 mvariableName? = divAsInt(m, 16)value or expression?; // assignment243 } // end while } // end if return hvalue or expression?;244 } // end function

Example of large numbers

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

+main 245 +for nitem? in range(50, 73)source? 246 variable npname? set to pow(2, n).floor()value or expression?247 call printTabprocedureName?(n.toString().length(), $"{n}"arguments?)248 call printTabprocedureName?(30 - np.toString().length(), $"{np}\n"arguments?)249 end for end main
+def main() -> None: 250 +for nitem? in range(50, 73)source?: 251 npname? = pow(2, n).floor()value or expression? # variable definition252 printTabprocedureName?(n.toString().length(), f"{n}"arguments?) # procedure call253 printTabprocedureName?(30 - np.toString().length(), f"{np}\n"arguments?) # procedure call254 # end for # end main
+static void main() { 255 +foreach (var nitem? in range(50, 73)source?) { 256 var npname? = pow(2, n).floor()value or expression?;257 printTabprocedureName?(n.toString().length(), $"{n}"arguments?); // procedure call258 printTabprocedureName?(30 - np.toString().length(), $"{np}\n"arguments?); // procedure call259 } // end foreach } // end main
+Sub main() 260 +For Each nitem? In range(50, 73)source? 261 Dim npname? = pow(2, n).floor()value or expression? ' variable definition262 printTabprocedureName?(n.toString().length(), $"{n}"arguments?) ' procedure call263 printTabprocedureName?(30 - np.toString().length(), $"{np}\n"arguments?) ' procedure call264 Next n End Sub
+static void main() { 265 +foreach (var nitem? in range(50, 73)source?) { 266 var npname? = pow(2, n).floor()value or expression?;267 printTabprocedureName?(n.toString().length(), String.format("%", n)arguments?); // procedure call268 printTabprocedureName?(30 - np.toString().length(), String.format("%\n", np)arguments?); // procedure call269 } // 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?20donename? = Truevalue or expression? # variable definition21var donename? = truevalue or expression?;22Dim donename? = Truevalue or expression? ' variable definition23var donename? = truevalue or expression?;24

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?25+titlename? = "Ulysses"literal value or data structure? # constant26+const String titlename? = "Ulysses"literal value or data structure?;27+Const titlename? = "Ulysses"literal value or data structure?28+static final String titlename? = "Ulysses"literal value or data structure?; // constant29 delimited by double quotes
StringstrstringStringString variable quotename? set to "'Hello', she said"value or expression?30quotename? = "'Hello', she said"value or expression? # variable definition31var quotename? = "'Hello', she said"value or expression?;32Dim quotename? = "'Hello', she said"value or expression? ' variable definition33var quotename? = "'Hello', she said"value or expression?;34 ' may be used in a string delimited by "
StringstrstringStringString variable emptyStringname? set to ""value or expression?35emptyStringname? = ""value or expression? # variable definition36var emptyStringname? = ""value or expression?;37Dim emptyStringname? = ""value or expression? ' variable definition38var emptyStringname? = ""value or expression?;39 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($"Spanish introduces a question with {unicode(191)}"arguments?)40print(f"Spanish introduces a question with {unicode(191)}"arguments?)41Console.WriteLine($"Spanish introduces a question with {unicode(191)}"arguments?); // print statement42Console.WriteLine($"Spanish introduces a question with {unicode(191)}"arguments?) ' print statement43System.out.println(String.format("Spanish introduces a question with %", unicode(191))arguments?); // print statement44 ⟶Spanish introduces a question with ¿
print($"This is an up arrow: {unicode(0x2191)}"arguments?)45print(f"This is an up arrow: {unicode(0x2191)}"arguments?)46Console.WriteLine($"This is an up arrow: {unicode(0x2191)}"arguments?); // print statement47Console.WriteLine($"This is an up arrow: {unicode(&H2191)}"arguments?) ' print statement48System.out.println(String.format("This is an up arrow: %", unicode(0x2191))arguments?); // print statement49 ⟶This is an up arrow: ↑

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

Manipulating strings

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

print("Hello " + "world"arguments?)50print("Hello " + "world"arguments?)51Console.WriteLine("Hello " + "world"arguments?); // print statement52Console.WriteLine("Hello " + "world"arguments?) ' print statement53System.out.println("Hello " + "world"arguments?); // print statement54 ⟶Hello world

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

print("Hello\nworld"arguments?)55print("Hello\nworld"arguments?)56Console.WriteLine("Hello\nworld"arguments?); // print statement57Console.WriteLine("Hello\nworld"arguments?) ' print statement58System.out.println("Hello\nworld"arguments?); // print statement59⟶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 list 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($"{a} times {b} equals {a*b}"arguments?)60print(f"{a} times {b} equals {a*b}"arguments?)61Console.WriteLine($"{a} times {b} equals {a*b}"arguments?); // print statement62Console.WriteLine($"{a} times {b} equals {a*b}"arguments?) ' print statement63System.out.println(String.format("% times % equals %", a, b, a*b)arguments?); // print statement64 ⟶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?65messagevariableName? = f"LANDED SAFELY AT SPEED {(velocity*100).floor()} FUEL {fuel.floor()}"value or expression? # assignment66messagevariableName? = $"LANDED SAFELY AT SPEED {(velocity*100).floor()} FUEL {fuel.floor()}"value or expression?; // assignment67messagevariableName? = $"LANDED SAFELY AT SPEED {(velocity*100).floor()} FUEL {fuel.floor()}"value or expression? ' assignment68messagevariableName? = String.format("LANDED SAFELY AT SPEED % FUEL %", (velocity*100).floor(), fuel.floor())value or expression?; // assignment69 print(messagearguments?)70print(messagearguments?)71Console.WriteLine(messagearguments?); // print statement72Console.WriteLine(messagearguments?) ' print statement73System.out.println(messagearguments?); // print statement74


⟶
LANDED SAFELY AT SPEED 300 FUEL 50

And for the area of a circle:

+main 275 variable rname? set to 2.0value or expression?276 print($"area = {(pi*r*r).round(2)}"arguments?)277 end main
+def main() -> None: 278 rname? = 2.0value or expression? # variable definition279 print(f"area = {(pi*r*r).round(2)}"arguments?)280 # end main
+static void main() { 281 var rname? = 2.0value or expression?;282 Console.WriteLine($"area = {(pi*r*r).round(2)}"arguments?); // print statement283 } // end main
+Sub main() 284 Dim rname? = 2.0value or expression? ' variable definition285 Console.WriteLine($"area = {(pi*r*r).round(2)}"arguments?) ' print statement286 End Sub
+static void main() { 287 var rname? = 2.0value or expression?;288 System.out.println(String.format("area = %", (pi*r*r).round(2))arguments?); // print statement289 } // 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		 Dictionary<of KeyType, ValueType>Dictionary[KeyType, ValueType]Dictionary<KeyType, ValueType>Dictionary(Of KeyType, ValueType)Dictionary<KeyType, ValueType>
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 Dictionary<of KeyType, ValueType>()Dictionary[KeyType, ValueType]()new Dictionary<KeyType, ValueType>()New Dictionary(Of KeyType, ValueType)()new Dictionary<KeyType, ValueType>() 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) 		createDictionarycreateDictionarycreateDictionarycreateDictionarycreateDictionary 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 List see Procedure methods on a Dictionary not available not available not available
function dot methods see Function dot methods on a List 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 List of n items are indexed from 0 to n-1.

To create a List, use either of:

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

A List'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 List of 'columns' each of which is a List of 'row' items, i.e. it is a List of Lists 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 List of Lists 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 List, that value must be of the same type as defined for the List's items.

procedure
method		 arguments action
append value of ListlistListListList item's type the item is added to the end of the List
appendList ListlistListListList the argument List is added to the end of the List
initialise IntintintIntegerint,
value of ListlistListListList item's type		 specify the number (> 0) of items in the List,
and an initial value for every item.
May be called at any time to redefine the List'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 list'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 List
prependList ListlistListListList the argument List is added to the start of the List
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 List
contains value BooleanboolboolBooleanboolean trueTruetrueTruetrue if the List contains the specified item
– falseFalsefalseFalsefalse otherwise
equals ListlistListListList BooleanboolboolBooleanboolean trueTruetrueTruetrue if list and argument are identical
– falseFalsefalseFalsefalse otherwise
filter lambdalambdalambdalambdalambda ListlistListListList a new List obtained from applying a lambda to the input List
see filter in HoFs
head (none) ListlistListListList item's type the first item of the List (i.e. index = 0, which must exist)
indexOf value of ListlistListListList item's type IntintintIntegerint the index of the first occurrence of the argument value in the List,
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 list,
with the specified String (which can be empty) inserted between the items
length (none) IntintintIntegerint the number of items in the List
map lambdalambdalambdalambdalambda ListlistListListList a new List obtained from applying a lambda to the input List
see map in HoFs
maxBy lambdalambdalambdalambdalambda ListlistListListList item's type the list item corresponding to the maximum of the values returned by a lambda
see maxBy in HoFs
minBy lambdalambdalambdalambdalambda ListlistListListList item's type the list item corresponding to the minimum of the values returned by a lambda
see minBy in HoFs
notEqualTo ListlistListListList BooleanboolboolBooleanboolean trueTruetrueTruetrue if list and argument differ l
– falseFalsefalseFalsefalse otherwise
orderBy lambdalambdalambdalambdalambda ListlistListListList a new list 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 List
taking account of the first argument as an initial (and default return) value
see reduce in HoFs
subList IntintintIntegerint, IntintintIntegerint ListlistListListList a new list that contains the items specified by the two positive integers (m,n) where
m indexes the first item of the list required (counting from 0) and
n indexes the item after the last item required (exclusive index)
if m ≥ n the result is the empty list
tail (none) ListlistListListList item's type all items except the first item in the List (i.e. index = 1..n, which must exist)
toString (none) StringstrstringStringString a String that is a comma+space-separated list of the List's items, enclosed in square brackets
withAppend item of ListlistListListList item's type ListlistListListList a new List lengthened with the item added after the end
withAppendList ListlistListListList of same type ListlistListListList a new List lengthened by appending the given List
withInsert IntintintIntegerint,
value of ListlistListListList item's type		 ListlistListListList a new List with the item inserted after the item at the given index position
withPrepend value of ListlistListListList item's type ListlistListListList a new List lengthened with the item added before the beginning
withPrependList ListlistListListList of same type ListlistListListList a new List lengthened by prepending the given List
withRemoveAll value of ListlistListListList item's type ListlistListListList a new List with items equal to the given item removed
withRemoveAt IntintintIntegerint ListlistListListList a new List with the item at the given index removed
withRemoveFirst value of ListlistListListList item's type ListlistListListList a new List with the first item equal to the given item removed
withSet IntintintIntegerint,
value of ListlistListListList item's type		 ListlistListListList a new List with the item replacing that at the given index

Dictionary

A DictionaryDictionaryDictionaryDictionaryDictionary is like a List 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 290 variable dLname? set to new Dictionary<of String, Int>()value or expression?291 variable dLRefname? set to new AsRef<of Dictionary<of String, Int>>(dL)value or expression?292 call greekLettersprocedureName?(dLRefarguments?)293 assign dLvariableName? to dLRef.value()value or expression?294 print(dLarguments?)295 call printDprocedureName?(dLarguments?)296 print(getDItem(dL, "alpha")arguments?)297 end main
+def main() -> None: 298 dLname? = Dictionary[str, int]()value or expression? # variable definition299 dLRefname? = AsRef[Dictionary[str, int]](dL)value or expression? # variable definition300 greekLettersprocedureName?(dLRefarguments?) # procedure call301 dLvariableName? = dLRef.value()value or expression? # assignment302 print(dLarguments?)303 printDprocedureName?(dLarguments?) # procedure call304 print(getDItem(dL, "alpha")arguments?)305 # end main
+static void main() { 306 var dLname? = new Dictionary<string, int>()value or expression?;307 var dLRefname? = new AsRef<Dictionary<string, int>>(dL)value or expression?;308 greekLettersprocedureName?(dLRefarguments?); // procedure call309 dLvariableName? = dLRef.value()value or expression?; // assignment310 Console.WriteLine(dLarguments?); // print statement311 printDprocedureName?(dLarguments?); // procedure call312 Console.WriteLine(getDItem(dL, "alpha")arguments?); // print statement313 } // end main
+Sub main() 314 Dim dLname? = New Dictionary(Of String, Integer)()value or expression? ' variable definition315 Dim dLRefname? = New AsRef(Of Dictionary(Of String, Integer))(dL)value or expression? ' variable definition316 greekLettersprocedureName?(dLRefarguments?) ' procedure call317 dLvariableName? = dLRef.value()value or expression? ' assignment318 Console.WriteLine(dLarguments?) ' print statement319 printDprocedureName?(dLarguments?) ' procedure call320 Console.WriteLine(getDItem(dL, "alpha")arguments?) ' print statement321 End Sub
+static void main() { 322 var dLname? = new Dictionary<String, int>()value or expression?;323 var dLRefname? = new AsRef<Dictionary<String, int>>(dL)value or expression?;324 greekLettersprocedureName?(dLRefarguments?); // procedure call325 dLvariableName? = dLRef.value()value or expression?; // assignment326 System.out.println(dLarguments?); // print statement327 printDprocedureName?(dLarguments?); // procedure call328 System.out.println(getDItem(dL, "alpha")arguments?); // print statement329 } // end main

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

+main 330 variable diname? set to createDictionary([("alpha", 1), ("beta", 2), ("gamma", 3)])value or expression?331 print(di["beta"]arguments?)332 end main
+def main() -> None: 333 diname? = createDictionary([("alpha", 1), ("beta", 2), ("gamma", 3)])value or expression? # variable definition334 print(di["beta"]arguments?)335 # end main
+static void main() { 336 var diname? = createDictionary(new [] {("alpha", 1), ("beta", 2), ("gamma", 3)})value or expression?;337 Console.WriteLine(di["beta"]arguments?); // print statement338 } // end main
+Sub main() 339 Dim diname? = createDictionary({("alpha", 1), ("beta", 2), ("gamma", 3)})value or expression? ' variable definition340 Console.WriteLine(di("beta")arguments?) ' print statement341 End Sub
+static void main() { 342 var diname? = createDictionary(list(("alpha", 1), ("beta", 2), ("gamma", 3)))value or expression?;343 System.out.println(di["beta"]arguments?); // print statement344 } // end main

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 List 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 List containing the values
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 (also referred to merely as a Set) is a standard data structure containing Set members, that works somewhat like a ListlistListListList with two important differences:

This enables a Set 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 Set from a literal List and changing its content:

variable stname? set to new HashSet<of Int>()value or expression?345
stname? = HashSet[int]()value or expression? # variable definition346
var stname? = new HashSet<int>()value or expression?;347
Dim stname? = New HashSet(Of Integer)()value or expression? ' variable definition348
var stname? = new HashSet<int>()value or expression?;349

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3


2

2
[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 List that are not already in the Set
asList (none) ListlistListListList a List containing the Set's members as List 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 list 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

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
push value
(of StackStackStackStackStack item's type)		 StackStackStackStackStack the Stack with the value added to its top
pop (none) StackStackStackStackStack item,
StackStackStackStackStack		 the topmost item of the Stack, and the Stack with the item removed
peek (none) StackStackStackStackStack item the topmost item on 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

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
enqueue value
(of QueueQueueQueueQueueQueue item's type)		 QueueQueueQueueQueueQueue the Queue with the item added to the end of the Queue
dequeue (none) QueueQueueQueueQueueQueue item,
QueueQueueQueueQueueQueue		 the next item in the Queue, and the Queue with the item removed
peek (none) QueueQueueQueueQueueQueue item the next item in 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

Examples using StackStackStackStackStack and QueueQueueQueueQueueQueue

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

+main 350 variable skname? set to new Stack<of String>()value or expression?351 print(sk.length()arguments?)352 assign skvariableName? to sk.push("apple")value or expression?353 assign skvariableName? to sk.push("banana")value or expression?354 assign skvariableName? to sk.push("cherry")value or expression?355 print(sk.length()arguments?)356 print(skarguments?)357 print(sk.peek()arguments?)358 print(sk.pop()arguments?)359 print(skarguments?)360 print(sk.pop().item_0arguments?)361 print(skarguments?)362 assign skvariableName? to sk.pop().item_1value or expression?363 print(skarguments?)364 end main
+def main() -> None: 365 skname? = Stack[str]()value or expression? # variable definition366 print(sk.length()arguments?)367 skvariableName? = sk.push("apple")value or expression? # assignment368 skvariableName? = sk.push("banana")value or expression? # assignment369 skvariableName? = sk.push("cherry")value or expression? # assignment370 print(sk.length()arguments?)371 print(skarguments?)372 print(sk.peek()arguments?)373 print(sk.pop()arguments?)374 print(skarguments?)375 print(sk.pop().item_0arguments?)376 print(skarguments?)377 skvariableName? = sk.pop().item_1value or expression? # assignment378 print(skarguments?)379 # end main
+static void main() { 380 var skname? = new Stack<string>()value or expression?;381 Console.WriteLine(sk.length()arguments?); // print statement382 skvariableName? = sk.push("apple")value or expression?; // assignment383 skvariableName? = sk.push("banana")value or expression?; // assignment384 skvariableName? = sk.push("cherry")value or expression?; // assignment385 Console.WriteLine(sk.length()arguments?); // print statement386 Console.WriteLine(skarguments?); // print statement387 Console.WriteLine(sk.peek()arguments?); // print statement388 Console.WriteLine(sk.pop()arguments?); // print statement389 Console.WriteLine(skarguments?); // print statement390 Console.WriteLine(sk.pop().item_0arguments?); // print statement391 Console.WriteLine(skarguments?); // print statement392 skvariableName? = sk.pop().item_1value or expression?; // assignment393 Console.WriteLine(skarguments?); // print statement394 } // end main
+Sub main() 395 Dim skname? = New Stack(Of String)()value or expression? ' variable definition396 Console.WriteLine(sk.length()arguments?) ' print statement397 skvariableName? = sk.push("apple")value or expression? ' assignment398 skvariableName? = sk.push("banana")value or expression? ' assignment399 skvariableName? = sk.push("cherry")value or expression? ' assignment400 Console.WriteLine(sk.length()arguments?) ' print statement401 Console.WriteLine(skarguments?) ' print statement402 Console.WriteLine(sk.peek()arguments?) ' print statement403 Console.WriteLine(sk.pop()arguments?) ' print statement404 Console.WriteLine(skarguments?) ' print statement405 Console.WriteLine(sk.pop().item_0arguments?) ' print statement406 Console.WriteLine(skarguments?) ' print statement407 skvariableName? = sk.pop().item_1value or expression? ' assignment408 Console.WriteLine(skarguments?) ' print statement409 End Sub
+static void main() { 410 var skname? = new Stack<String>()value or expression?;411 System.out.println(sk.length()arguments?); // print statement412 skvariableName? = sk.push("apple")value or expression?; // assignment413 skvariableName? = sk.push("banana")value or expression?; // assignment414 skvariableName? = sk.push("cherry")value or expression?; // assignment415 System.out.println(sk.length()arguments?); // print statement416 System.out.println(skarguments?); // print statement417 System.out.println(sk.peek()arguments?); // print statement418 System.out.println(sk.pop()arguments?); // print statement419 System.out.println(skarguments?); // print statement420 System.out.println(sk.pop().item_0arguments?); // print statement421 System.out.println(skarguments?); // print statement422 skvariableName? = sk.pop().item_1value or expression?; // assignment423 System.out.println(skarguments?); // print statement424 } // end main


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3
[cherry, banana, apple]
cherry
(cherry, [banana, apple])
[cherry, banana, apple]
cherry
[cherry, banana, apple]

[banana, apple]

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

+main 425 variable quname? set to new Queue<of String>()value or expression?426 print(qu.length()arguments?)427 assign quvariableName? to qu.enqueue("apple")value or expression?428 assign quvariableName? to qu.enqueue("banana")value or expression?429 assign quvariableName? to qu.enqueue("cherry")value or expression?430 print(qu.length()arguments?)431 print(quarguments?)432 print(qu.peek()arguments?)433 print(qu.dequeue()arguments?)434 print(quarguments?)435 print(qu.dequeue().item_0arguments?)436 print(quarguments?)437 assign quvariableName? to qu.dequeue().item_1value or expression?438 print(quarguments?)439 end main
+def main() -> None: 440 quname? = Queue[str]()value or expression? # variable definition441 print(qu.length()arguments?)442 quvariableName? = qu.enqueue("apple")value or expression? # assignment443 quvariableName? = qu.enqueue("banana")value or expression? # assignment444 quvariableName? = qu.enqueue("cherry")value or expression? # assignment445 print(qu.length()arguments?)446 print(quarguments?)447 print(qu.peek()arguments?)448 print(qu.dequeue()arguments?)449 print(quarguments?)450 print(qu.dequeue().item_0arguments?)451 print(quarguments?)452 quvariableName? = qu.dequeue().item_1value or expression? # assignment453 print(quarguments?)454 # end main
+static void main() { 455 var quname? = new Queue<string>()value or expression?;456 Console.WriteLine(qu.length()arguments?); // print statement457 quvariableName? = qu.enqueue("apple")value or expression?; // assignment458 quvariableName? = qu.enqueue("banana")value or expression?; // assignment459 quvariableName? = qu.enqueue("cherry")value or expression?; // assignment460 Console.WriteLine(qu.length()arguments?); // print statement461 Console.WriteLine(quarguments?); // print statement462 Console.WriteLine(qu.peek()arguments?); // print statement463 Console.WriteLine(qu.dequeue()arguments?); // print statement464 Console.WriteLine(quarguments?); // print statement465 Console.WriteLine(qu.dequeue().item_0arguments?); // print statement466 Console.WriteLine(quarguments?); // print statement467 quvariableName? = qu.dequeue().item_1value or expression?; // assignment468 Console.WriteLine(quarguments?); // print statement469 } // end main
+Sub main() 470 Dim quname? = New Queue(Of String)()value or expression? ' variable definition471 Console.WriteLine(qu.length()arguments?) ' print statement472 quvariableName? = qu.enqueue("apple")value or expression? ' assignment473 quvariableName? = qu.enqueue("banana")value or expression? ' assignment474 quvariableName? = qu.enqueue("cherry")value or expression? ' assignment475 Console.WriteLine(qu.length()arguments?) ' print statement476 Console.WriteLine(quarguments?) ' print statement477 Console.WriteLine(qu.peek()arguments?) ' print statement478 Console.WriteLine(qu.dequeue()arguments?) ' print statement479 Console.WriteLine(quarguments?) ' print statement480 Console.WriteLine(qu.dequeue().item_0arguments?) ' print statement481 Console.WriteLine(quarguments?) ' print statement482 quvariableName? = qu.dequeue().item_1value or expression? ' assignment483 Console.WriteLine(quarguments?) ' print statement484 End Sub
+static void main() { 485 var quname? = new Queue<String>()value or expression?;486 System.out.println(qu.length()arguments?); // print statement487 quvariableName? = qu.enqueue("apple")value or expression?; // assignment488 quvariableName? = qu.enqueue("banana")value or expression?; // assignment489 quvariableName? = qu.enqueue("cherry")value or expression?; // assignment490 System.out.println(qu.length()arguments?); // print statement491 System.out.println(quarguments?); // print statement492 System.out.println(qu.peek()arguments?); // print statement493 System.out.println(qu.dequeue()arguments?); // print statement494 System.out.println(quarguments?); // print statement495 System.out.println(qu.dequeue().item_0arguments?); // print statement496 System.out.println(quarguments?); // print statement497 quvariableName? = qu.dequeue().item_1value or expression?; // assignment498 System.out.println(quarguments?); // print statement499 } // end main


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[apple, banana, cherry]
apple
(apple, [banana, cherry])
[apple, banana, cherry]
apple
[apple, banana, cherry]

[banana, cherry]

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 List 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?145pointname? = (3, 4)value or expression? # variable definition146var pointname? = (3, 4)value or expression?;147Dim pointname? = (3, 4)value or expression? ' variable definition148var pointname? = (3, 4)value or expression?;149 variable tname? set to (3, "apple", true)value or expression?150tname? = (3, "apple", True)value or expression? # variable definition151var tname? = (3, "apple", true)value or expression?;152Dim tname? = (3, "apple", True)value or expression? ' variable definition153var tname? = (3, "apple", true)value or expression?;154

Accessing items in a Tuple

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

variable tname? set to (3, "apple", true)value or expression?500
tname? = (3, "apple", True)value or expression? # variable definition501
var tname? = (3, "apple", true)value or expression?;502
Dim tname? = (3, "apple", True)value or expression? ' variable definition503
var tname? = (3, "apple", true)value or expression?;504
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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? 505 return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?506 end function
+def distanceBetweenname?(p1: tuple[float, float], p2: tuple[float, float]parameter definitions?) -> floatType?: # function507 return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?508 # end function
+static doubleType? distanceBetweenname?((double, double) p1, (double, double) p2parameter definitions?) { // function509 return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?;510 } // end function
+Function distanceBetweenname?(p1 As (Double, Double), p2 As (Double, Double)parameter definitions?) As DoubleType? 511 Return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?512 End Function
+static doubleType? distanceBetweenname?((double, double) p1, (double, double) p2parameter definitions?) { // function513 return sqrt(pow(p2.item_0 - p1.item_0, 2) + pow(p2.item_1 - p1.item_1, 2))value or expression?;514 } // 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 515 variable gridname? set to createBlockGraphics(white)value or expression?516 +while truecondition? 517 variable xname? set to randint(0, 39)value or expression?518 variable yname? set to randint(0, 29)value or expression?519 variable colourname? set to randint(0, white - 1)value or expression?520 assign grid[x][y]variableName? to colourvalue or expression?521 call displayBlocksprocedureName?(gridarguments?)522 end while end main
+def main() -> None: 523 gridname? = createBlockGraphics(white)value or expression? # variable definition524 +while Truecondition?: 525 xname? = randint(0, 39)value or expression? # variable definition526 yname? = randint(0, 29)value or expression? # variable definition527 colourname? = randint(0, white - 1)value or expression? # variable definition528 grid[x][y]variableName? = colourvalue or expression? # assignment529 displayBlocksprocedureName?(gridarguments?) # procedure call530 # end while # end main
+static void main() { 531 var gridname? = createBlockGraphics(white)value or expression?;532 +while (truecondition?) { 533 var xname? = randint(0, 39)value or expression?;534 var yname? = randint(0, 29)value or expression?;535 var colourname? = randint(0, white - 1)value or expression?;536 grid[x][y]variableName? = colourvalue or expression?; // assignment537 displayBlocksprocedureName?(gridarguments?); // procedure call538 } // end while } // end main
+Sub main() 539 Dim gridname? = createBlockGraphics(white)value or expression? ' variable definition540 +While Truecondition? 541 Dim xname? = randint(0, 39)value or expression? ' variable definition542 Dim yname? = randint(0, 29)value or expression? ' variable definition543 Dim colourname? = randint(0, white - 1)value or expression? ' variable definition544 grid(x)(y)variableName? = colourvalue or expression? ' assignment545 displayBlocksprocedureName?(gridarguments?) ' procedure call546 End While End Sub
+static void main() { 547 var gridname? = createBlockGraphics(white)value or expression?;548 +while (truecondition?) { 549 var xname? = randint(0, 39)value or expression?;550 var yname? = randint(0, 29)value or expression?;551 var colourname? = randint(0, white - 1)value or expression?;552 grid[x][y]variableName? = colourvalue or expression?; // assignment553 displayBlocksprocedureName?(gridarguments?); // procedure call554 } // 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 555 variable tname? set to new Turtle()value or expression?556 call t.placeAtprocedureName?(-75, 50arguments?)557 call t.showprocedureName?(arguments?)558 +for iitem? in range(1, 5)source? 559 call t.turnprocedureName?(90arguments?)560 call t.moveprocedureName?(80arguments?)561 call sleepprocedureName?(0.5arguments?)562 end for end main
+def main() -> None: 563 tname? = Turtle()value or expression? # variable definition564 t.placeAtprocedureName?(-75, 50arguments?) # procedure call565 t.showprocedureName?(arguments?) # procedure call566 +for iitem? in range(1, 5)source?: 567 t.turnprocedureName?(90arguments?) # procedure call568 t.moveprocedureName?(80arguments?) # procedure call569 sleepprocedureName?(0.5arguments?) # procedure call570 # end for # end main
+static void main() { 571 var tname? = new Turtle()value or expression?;572 t.placeAtprocedureName?(-75, 50arguments?); // procedure call573 t.showprocedureName?(arguments?); // procedure call574 +foreach (var iitem? in range(1, 5)source?) { 575 t.turnprocedureName?(90arguments?); // procedure call576 t.moveprocedureName?(80arguments?); // procedure call577 sleepprocedureName?(0.5arguments?); // procedure call578 } // end foreach } // end main
+Sub main() 579 Dim tname? = New Turtle()value or expression? ' variable definition580 t.placeAtprocedureName?(-75, 50arguments?) ' procedure call581 t.showprocedureName?(arguments?) ' procedure call582 +For Each iitem? In range(1, 5)source? 583 t.turnprocedureName?(90arguments?) ' procedure call584 t.moveprocedureName?(80arguments?) ' procedure call585 sleepprocedureName?(0.5arguments?) ' procedure call586 Next i End Sub
+static void main() { 587 var tname? = new Turtle()value or expression?;588 t.placeAtprocedureName?(-75, 50arguments?); // procedure call589 t.showprocedureName?(arguments?); // procedure call590 +foreach (var iitem? in range(1, 5)source?) { 591 t.turnprocedureName?(90arguments?); // procedure call592 t.moveprocedureName?(80arguments?); // procedure call593 sleepprocedureName?(0.5arguments?); // procedure call594 } // end foreach } // end main

Turtle square

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

+main 595 variable tname? set to new Turtle()value or expression?596 call t.placeAtprocedureName?(-50, 30arguments?)597 call t.turnprocedureName?(90arguments?)598 call t.showprocedureName?(arguments?)599 +for iitem? in range(1, 4)source? 600 call drawSideprocedureName?(side, targuments?)601 call t.turnprocedureName?(120arguments?)602 end for end main
+def main() -> None: 603 tname? = Turtle()value or expression? # variable definition604 t.placeAtprocedureName?(-50, 30arguments?) # procedure call605 t.turnprocedureName?(90arguments?) # procedure call606 t.showprocedureName?(arguments?) # procedure call607 +for iitem? in range(1, 4)source?: 608 drawSideprocedureName?(side, targuments?) # procedure call609 t.turnprocedureName?(120arguments?) # procedure call610 # end for # end main
+static void main() { 611 var tname? = new Turtle()value or expression?;612 t.placeAtprocedureName?(-50, 30arguments?); // procedure call613 t.turnprocedureName?(90arguments?); // procedure call614 t.showprocedureName?(arguments?); // procedure call615 +foreach (var iitem? in range(1, 4)source?) { 616 drawSideprocedureName?(side, targuments?); // procedure call617 t.turnprocedureName?(120arguments?); // procedure call618 } // end foreach } // end main
+Sub main() 619 Dim tname? = New Turtle()value or expression? ' variable definition620 t.placeAtprocedureName?(-50, 30arguments?) ' procedure call621 t.turnprocedureName?(90arguments?) ' procedure call622 t.showprocedureName?(arguments?) ' procedure call623 +For Each iitem? In range(1, 4)source? 624 drawSideprocedureName?(side, targuments?) ' procedure call625 t.turnprocedureName?(120arguments?) ' procedure call626 Next i End Sub
+static void main() { 627 var tname? = new Turtle()value or expression?;628 t.placeAtprocedureName?(-50, 30arguments?); // procedure call629 t.turnprocedureName?(90arguments?); // procedure call630 t.showprocedureName?(arguments?); // procedure call631 +foreach (var iitem? in range(1, 4)source?) { 632 drawSideprocedureName?(side, targuments?); // procedure call633 t.turnprocedureName?(120arguments?); // procedure call634 } // end foreach } // end main

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 - widthstroke - widthstroke - widthstroke - widthstroke - 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 list 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 list of shapes is not displayed until call procedure displayVectorGraphics with the list 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 635 variable vgname? set to createVectorGraphics()value or expression?636 variable circname? set to new CircleVG()value or expression?637 call circ.setCentreXprocedureName?(20arguments?)638 call circ.setCentreYprocedureName?(20arguments?)639 call circ.setRadiusprocedureName?(5arguments?)640 call circ.setFillColourprocedureName?(greenarguments?)641 call circ.setStrokeColourprocedureName?(redarguments?)642 call circ.setStrokeWidthprocedureName?(2arguments?)643 call vg.appendprocedureName?(circarguments?)644 call displayVectorGraphicsprocedureName?(vgarguments?)645 end main
+def main() -> None: 646 vgname? = createVectorGraphics()value or expression? # variable definition647 circname? = CircleVG()value or expression? # variable definition648 circ.setCentreXprocedureName?(20arguments?) # procedure call649 circ.setCentreYprocedureName?(20arguments?) # procedure call650 circ.setRadiusprocedureName?(5arguments?) # procedure call651 circ.setFillColourprocedureName?(greenarguments?) # procedure call652 circ.setStrokeColourprocedureName?(redarguments?) # procedure call653 circ.setStrokeWidthprocedureName?(2arguments?) # procedure call654 vg.appendprocedureName?(circarguments?) # procedure call655 displayVectorGraphicsprocedureName?(vgarguments?) # procedure call656 # end main
+static void main() { 657 var vgname? = createVectorGraphics()value or expression?;658 var circname? = new CircleVG()value or expression?;659 circ.setCentreXprocedureName?(20arguments?); // procedure call660 circ.setCentreYprocedureName?(20arguments?); // procedure call661 circ.setRadiusprocedureName?(5arguments?); // procedure call662 circ.setFillColourprocedureName?(greenarguments?); // procedure call663 circ.setStrokeColourprocedureName?(redarguments?); // procedure call664 circ.setStrokeWidthprocedureName?(2arguments?); // procedure call665 vg.appendprocedureName?(circarguments?); // procedure call666 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call667 } // end main
+Sub main() 668 Dim vgname? = createVectorGraphics()value or expression? ' variable definition669 Dim circname? = New CircleVG()value or expression? ' variable definition670 circ.setCentreXprocedureName?(20arguments?) ' procedure call671 circ.setCentreYprocedureName?(20arguments?) ' procedure call672 circ.setRadiusprocedureName?(5arguments?) ' procedure call673 circ.setFillColourprocedureName?(greenarguments?) ' procedure call674 circ.setStrokeColourprocedureName?(redarguments?) ' procedure call675 circ.setStrokeWidthprocedureName?(2arguments?) ' procedure call676 vg.appendprocedureName?(circarguments?) ' procedure call677 displayVectorGraphicsprocedureName?(vgarguments?) ' procedure call678 End Sub
+static void main() { 679 var vgname? = createVectorGraphics()value or expression?;680 var circname? = new CircleVG()value or expression?;681 circ.setCentreXprocedureName?(20arguments?); // procedure call682 circ.setCentreYprocedureName?(20arguments?); // procedure call683 circ.setRadiusprocedureName?(5arguments?); // procedure call684 circ.setFillColourprocedureName?(greenarguments?); // procedure call685 circ.setStrokeColourprocedureName?(redarguments?); // procedure call686 circ.setStrokeWidthprocedureName?(2arguments?); // procedure call687 vg.appendprocedureName?(circarguments?); // procedure call688 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call689 } // end main

circle

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

+main 690 variable vgname? set to new List<of VectorGraphic>()value or expression?691 variable circname? set to new CircleVG()value or expression?692 call circ.setCentreXprocedureName?(50arguments?)693 call circ.setCentreYprocedureName?(37.5arguments?)694 call circ.setRadiusprocedureName?(30arguments?)695 call circ.setFillColourprocedureName?(greenarguments?)696 call vg.appendprocedureName?(circarguments?)697 +while truecondition? 698 call displayVectorGraphicsprocedureName?(vgarguments?)699 call sleepprocedureName?(1arguments?)700 call circ.setFillColourprocedureName?(redarguments?)701 call displayVectorGraphicsprocedureName?(vgarguments?)702 call sleepprocedureName?(1arguments?)703 call circ.setFillColourprocedureName?(greenarguments?)704 end while call displayVectorGraphicsprocedureName?(vgarguments?)705 end main
+def main() -> None: 706 vgname? = list[VectorGraphic]()value or expression? # variable definition707 circname? = CircleVG()value or expression? # variable definition708 circ.setCentreXprocedureName?(50arguments?) # procedure call709 circ.setCentreYprocedureName?(37.5arguments?) # procedure call710 circ.setRadiusprocedureName?(30arguments?) # procedure call711 circ.setFillColourprocedureName?(greenarguments?) # procedure call712 vg.appendprocedureName?(circarguments?) # procedure call713 +while Truecondition?: 714 displayVectorGraphicsprocedureName?(vgarguments?) # procedure call715 sleepprocedureName?(1arguments?) # procedure call716 circ.setFillColourprocedureName?(redarguments?) # procedure call717 displayVectorGraphicsprocedureName?(vgarguments?) # procedure call718 sleepprocedureName?(1arguments?) # procedure call719 circ.setFillColourprocedureName?(greenarguments?) # procedure call720 # end while displayVectorGraphicsprocedureName?(vgarguments?) # procedure call721 # end main
+static void main() { 722 var vgname? = new List<VectorGraphic>()value or expression?;723 var circname? = new CircleVG()value or expression?;724 circ.setCentreXprocedureName?(50arguments?); // procedure call725 circ.setCentreYprocedureName?(37.5arguments?); // procedure call726 circ.setRadiusprocedureName?(30arguments?); // procedure call727 circ.setFillColourprocedureName?(greenarguments?); // procedure call728 vg.appendprocedureName?(circarguments?); // procedure call729 +while (truecondition?) { 730 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call731 sleepprocedureName?(1arguments?); // procedure call732 circ.setFillColourprocedureName?(redarguments?); // procedure call733 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call734 sleepprocedureName?(1arguments?); // procedure call735 circ.setFillColourprocedureName?(greenarguments?); // procedure call736 } // end while displayVectorGraphicsprocedureName?(vgarguments?); // procedure call737 } // end main
+Sub main() 738 Dim vgname? = New List(Of VectorGraphic)()value or expression? ' variable definition739 Dim circname? = New CircleVG()value or expression? ' variable definition740 circ.setCentreXprocedureName?(50arguments?) ' procedure call741 circ.setCentreYprocedureName?(37.5arguments?) ' procedure call742 circ.setRadiusprocedureName?(30arguments?) ' procedure call743 circ.setFillColourprocedureName?(greenarguments?) ' procedure call744 vg.appendprocedureName?(circarguments?) ' procedure call745 +While Truecondition? 746 displayVectorGraphicsprocedureName?(vgarguments?) ' procedure call747 sleepprocedureName?(1arguments?) ' procedure call748 circ.setFillColourprocedureName?(redarguments?) ' procedure call749 displayVectorGraphicsprocedureName?(vgarguments?) ' procedure call750 sleepprocedureName?(1arguments?) ' procedure call751 circ.setFillColourprocedureName?(greenarguments?) ' procedure call752 End While displayVectorGraphicsprocedureName?(vgarguments?) ' procedure call753 End Sub
+static void main() { 754 var vgname? = new List<VectorGraphic>()value or expression?;755 var circname? = new CircleVG()value or expression?;756 circ.setCentreXprocedureName?(50arguments?); // procedure call757 circ.setCentreYprocedureName?(37.5arguments?); // procedure call758 circ.setRadiusprocedureName?(30arguments?); // procedure call759 circ.setFillColourprocedureName?(greenarguments?); // procedure call760 vg.appendprocedureName?(circarguments?); // procedure call761 +while (truecondition?) { 762 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call763 sleepprocedureName?(1arguments?); // procedure call764 circ.setFillColourprocedureName?(redarguments?); // procedure call765 displayVectorGraphicsprocedureName?(vgarguments?); // procedure call766 sleepprocedureName?(1arguments?); // procedure call767 circ.setFillColourprocedureName?(greenarguments?); // procedure call768 } // end while displayVectorGraphicsprocedureName?(vgarguments?); // procedure call769 } // 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 770 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?771 variable rawname? set to (new RawVG()).withContent(movingCircle)value or expression?772 call displayVectorGraphicsprocedureName?([raw]arguments?)773 end main
+def main() -> None: 774 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 definition775 rawname? = (RawVG()).withContent(movingCircle)value or expression? # variable definition776 displayVectorGraphicsprocedureName?([raw]arguments?) # procedure call777 # end main
+static void main() { 778 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?;779 var rawname? = (new RawVG()).withContent(movingCircle)value or expression?;780 displayVectorGraphicsprocedureName?(new [] {raw}arguments?); // procedure call781 } // end main
+Sub main() 782 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 definition783 Dim rawname? = (New RawVG()).withContent(movingCircle)value or expression? ' variable definition784 displayVectorGraphicsprocedureName?({raw}arguments?) ' procedure call785 End Sub
+static void main() { 786 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?;787 var rawname? = (new RawVG()).withContent(movingCircle)value or expression?;788 displayVectorGraphicsprocedureName?(list(raw)arguments?); // procedure call789 } // 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 RRRRR 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?155rndname? = Random()value or expression? # variable definition156var rndname? = new Random()value or expression?;157Dim rndname? = New Random()value or expression? ' variable definition158var rndname? = new Random()value or expression?;159
call rnd.initialiseFromClockprocedureName?(arguments?)160rnd.initialiseFromClockprocedureName?(arguments?) # procedure call161rnd.initialiseFromClockprocedureName?(arguments?); // procedure call162rnd.initialiseFromClockprocedureName?(arguments?) ' procedure call163rnd.initialiseFromClockprocedureName?(arguments?); // procedure call164

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 790 variable rndname? set to new Random()value or expression?791 call rnd.initialiseFromClockprocedureName?(arguments?)792 +for iitem? in range(1, 20)source? 793 print(randomThrow(rnd).item_0arguments?)794 assign rndvariableName? to randomThrow(rnd).item_1value or expression?795 end for end main
+def main() -> None: 796 rndname? = Random()value or expression? # variable definition797 rnd.initialiseFromClockprocedureName?(arguments?) # procedure call798 +for iitem? in range(1, 20)source?: 799 print(randomThrow(rnd).item_0arguments?)800 rndvariableName? = randomThrow(rnd).item_1value or expression? # assignment801 # end for # end main
+static void main() { 802 var rndname? = new Random()value or expression?;803 rnd.initialiseFromClockprocedureName?(arguments?); // procedure call804 +foreach (var iitem? in range(1, 20)source?) { 805 Console.WriteLine(randomThrow(rnd).item_0arguments?); // print statement806 rndvariableName? = randomThrow(rnd).item_1value or expression?; // assignment807 } // end foreach } // end main
+Sub main() 808 Dim rndname? = New Random()value or expression? ' variable definition809 rnd.initialiseFromClockprocedureName?(arguments?) ' procedure call810 +For Each iitem? In range(1, 20)source? 811 Console.WriteLine(randomThrow(rnd).item_0arguments?) ' print statement812 rndvariableName? = randomThrow(rnd).item_1value or expression? ' assignment813 Next i End Sub
+static void main() { 814 var rndname? = new Random()value or expression?;815 rnd.initialiseFromClockprocedureName?(arguments?); // procedure call816 +foreach (var iitem? in range(1, 20)source?) { 817 System.out.println(randomThrow(rnd).item_0arguments?); // print statement818 rndvariableName? = randomThrow(rnd).item_1value or expression?; // assignment819 } // end foreach } // end main

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""-1""-1""-1""-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 list.
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 820 variable key1name? set to getKey()value or expression?821 variable key2name? set to getNumericKey()value or expression?822 variable kmname? set to getKeyWithModifier()value or expression?823 variable keyCapname? set to km.item_0value or expression?824 variable keyModname? set to km.item_1value or expression?825 end main
+def main() -> None: 826 key1name? = getKey()value or expression? # variable definition827 key2name? = getNumericKey()value or expression? # variable definition828 kmname? = getKeyWithModifier()value or expression? # variable definition829 keyCapname? = km.item_0value or expression? # variable definition830 keyModname? = km.item_1value or expression? # variable definition831 # end main
+static void main() { 832 var key1name? = getKey()value or expression?;833 var key2name? = getNumericKey()value or expression?;834 var kmname? = getKeyWithModifier()value or expression?;835 var keyCapname? = km.item_0value or expression?;836 var keyModname? = km.item_1value or expression?;837 } // end main
+Sub main() 838 Dim key1name? = getKey()value or expression? ' variable definition839 Dim key2name? = getNumericKey()value or expression? ' variable definition840 Dim kmname? = getKeyWithModifier()value or expression? ' variable definition841 Dim keyCapname? = km.item_0value or expression? ' variable definition842 Dim keyModname? = km.item_1value or expression? ' variable definition843 End Sub
+static void main() { 844 var key1name? = getKey()value or expression?;845 var key2name? = getNumericKey()value or expression?;846 var kmname? = getKeyWithModifier()value or expression?;847 var keyCapname? = km.item_0value or expression?;848 var keyModname? = km.item_1value or expression?;849 } // end main
+main 850 call pressAnyKeyToContinueprocedureName?(arguments?)851 print("OK, press A or B"arguments?)852 variable keyname? set to waitForKey()value or expression?853 print($"That was {key}"arguments?)854 end main
+def main() -> None: 855 pressAnyKeyToContinueprocedureName?(arguments?) # procedure call856 print("OK, press A or B"arguments?)857 keyname? = waitForKey()value or expression? # variable definition858 print(f"That was {key}"arguments?)859 # end main
+static void main() { 860 pressAnyKeyToContinueprocedureName?(arguments?); // procedure call861 Console.WriteLine("OK, press A or B"arguments?); // print statement862 var keyname? = waitForKey()value or expression?;863 Console.WriteLine($"That was {key}"arguments?); // print statement864 } // end main
+Sub main() 865 pressAnyKeyToContinueprocedureName?(arguments?) ' procedure call866 Console.WriteLine("OK, press A or B"arguments?) ' print statement867 Dim keyname? = waitForKey()value or expression? ' variable definition868 Console.WriteLine($"That was {key}"arguments?) ' print statement869 End Sub
+static void main() { 870 pressAnyKeyToContinueprocedureName?(arguments?); // procedure call871 System.out.println("OK, press A or B"arguments?); // print statement872 var keyname? = waitForKey()value or expression?;873 System.out.println(String.format("That was %", key)arguments?); // print statement874 } // 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 875 variable filename? set to createFileForWriting("myFile.txt")value or expression?876 call file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?)877 end main
+def main() -> None: 878 filename? = createFileForWriting("myFile.txt")value or expression? # variable definition879 file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?) # procedure call880 # end main
+static void main() { 881 var filename? = createFileForWriting("myFile.txt")value or expression?;882 file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?); // procedure call883 } // end main
+Sub main() 884 Dim filename? = createFileForWriting("myFile.txt")value or expression? ' variable definition885 file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?) ' procedure call886 End Sub
+static void main() { 887 var filename? = createFileForWriting("myFile.txt")value or expression?;888 file.writeWholeFileprocedureName?("Text line 1\nText line 2"arguments?); // procedure call889 } // 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 890 variable filename? set to openFileForReading()value or expression?891 variable textname? set to file.readWholeFile()value or expression?892 print(textarguments?)893 end main
+def main() -> None: 894 filename? = openFileForReading()value or expression? # variable definition895 textname? = file.readWholeFile()value or expression? # variable definition896 print(textarguments?)897 # end main
+static void main() { 898 var filename? = openFileForReading()value or expression?;899 var textname? = file.readWholeFile()value or expression?;900 Console.WriteLine(textarguments?); // print statement901 } // end main
+Sub main() 902 Dim filename? = openFileForReading()value or expression? ' variable definition903 Dim textname? = file.readWholeFile()value or expression? ' variable definition904 Console.WriteLine(textarguments?) ' print statement905 End Sub
+static void main() { 906 var filename? = openFileForReading()value or expression?;907 var textname? = file.readWholeFile()value or expression?;908 System.out.println(textarguments?); // print statement909 } // 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?)910
displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?) # procedure call911
displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?); // procedure call912
displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?) ' procedure call913
displayHtmlprocedureName?("<h1 style='color: blue;'>A heading</h1><p>some text</p>"arguments?); // procedure call914

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 915 variable stylename? set to "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression?916 call displayHtmlprocedureName?($"{style}<h1>New heading</h1><p>some new text</p>"arguments?)917 end main
+def main() -> None: 918 stylename? = "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression? # variable definition919 displayHtmlprocedureName?(f"{style}<h1>New heading</h1><p>some new text</p>"arguments?) # procedure call920 # end main
+static void main() { 921 var stylename? = "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression?;922 displayHtmlprocedureName?($"{style}<h1>New heading</h1><p>some new text</p>"arguments?); // procedure call923 } // end main
+Sub main() 924 Dim stylename? = "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression? ' variable definition925 displayHtmlprocedureName?($"{style}<h1>New heading</h1><p>some new text</p>"arguments?) ' procedure call926 End Sub
+static void main() { 927 var stylename? = "<style> h1 { color: Red; font-size: 24pt; } p { font-family: Serif; } </style>"value or expression?;928 displayHtmlprocedureName?(String.format("%<h1>New heading</h1><p>some new text</p>", style)arguments?); // procedure call929 } // 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 980 variable scalename? set to [262, 294, 330, 349, 392, 440, 494, 523]value or expression?981 variable scaleLname? set to scale.length()value or expression?982 variable quavername? set to 250value or expression?983 variable volumename? set to 1.5value or expression?984 +for iitem? in range(0, scaleL)source? 985 call toneprocedureName?(quaver, scale[i], volumearguments?)986 end for call sleepprocedureName?(1arguments?)987 +for iitem? in range(0, scaleL)source? 988 call toneprocedureName?(quaver, scale[scaleL - 1 - i], volumearguments?)989 end for end main
+def main() -> None: 990 scalename? = [262, 294, 330, 349, 392, 440, 494, 523]value or expression? # variable definition991 scaleLname? = scale.length()value or expression? # variable definition992 quavername? = 250value or expression? # variable definition993 volumename? = 1.5value or expression? # variable definition994 +for iitem? in range(0, scaleL)source?: 995 toneprocedureName?(quaver, scale[i], volumearguments?) # procedure call996 # end for sleepprocedureName?(1arguments?) # procedure call997 +for iitem? in range(0, scaleL)source?: 998 toneprocedureName?(quaver, scale[scaleL - 1 - i], volumearguments?) # procedure call999 # end for # end main
+static void main() { 1000 var scalename? = new [] {262, 294, 330, 349, 392, 440, 494, 523}value or expression?;1001 var scaleLname? = scale.length()value or expression?;1002 var quavername? = 250value or expression?;1003 var volumename? = 1.5value or expression?;1004 +foreach (var iitem? in range(0, scaleL)source?) { 1005 toneprocedureName?(quaver, scale[i], volumearguments?); // procedure call1006 } // end foreach sleepprocedureName?(1arguments?); // procedure call1007 +foreach (var iitem? in range(0, scaleL)source?) { 1008 toneprocedureName?(quaver, scale[scaleL - 1 - i], volumearguments?); // procedure call1009 } // end foreach } // end main
+Sub main() 1010 Dim scalename? = {262, 294, 330, 349, 392, 440, 494, 523}value or expression? ' variable definition1011 Dim scaleLname? = scale.length()value or expression? ' variable definition1012 Dim quavername? = 250value or expression? ' variable definition1013 Dim volumename? = 1.5value or expression? ' variable definition1014 +For Each iitem? In range(0, scaleL)source? 1015 toneprocedureName?(quaver, scale(i), volumearguments?) ' procedure call1016 Next i sleepprocedureName?(1arguments?) ' procedure call1017 +For Each iitem? In range(0, scaleL)source? 1018 toneprocedureName?(quaver, scale(scaleL - 1 - i), volumearguments?) ' procedure call1019 Next i End Sub
+static void main() { 1020 var scalename? = list(262, 294, 330, 349, 392, 440, 494, 523)value or expression?;1021 var scaleLname? = scale.length()value or expression?;1022 var quavername? = 250value or expression?;1023 var volumename? = 1.5value or expression?;1024 +foreach (var iitem? in range(0, scaleL)source?) { 1025 toneprocedureName?(quaver, scale[i], volumearguments?); // procedure call1026 } // end foreach sleepprocedureName?(1arguments?); // procedure call1027 +foreach (var iitem? in range(0, scaleL)source?) { 1028 toneprocedureName?(quaver, scale[scaleL - 1 - i], volumearguments?); // procedure call1029 } // 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.
withSet
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 list returned by method keys on the dictionary:
    print(di.keys().length()arguments?)165print(di.keys().length()arguments?)166Console.WriteLine(di.keys().length()arguments?); // print statement167Console.WriteLine(di.keys().length()arguments?) ' print statement168System.out.println(di.keys().length()arguments?); // print statement169⟶15
  4. Checking whether an item is contained in a DictionaryDictionaryDictionaryDictionaryDictionary can be done by applying method contains to the list returned by methods keys and values on the dictionary:
    print(di.keys().contains("widget")arguments?)170print(di.keys().contains("widget")arguments?)171Console.WriteLine(di.keys().contains("widget")arguments?); // print statement172Console.WriteLine(di.keys().contains("widget")arguments?) ' print statement173System.out.println(di.keys().contains("widget")arguments?); // print statement174⟶true or false
    print(di.values().contains(42)arguments?)175print(di.values().contains(42)arguments?)176Console.WriteLine(di.values().contains(42)arguments?); // print statement177Console.WriteLine(di.values().contains(42)arguments?) ' print statement178System.out.println(di.values().contains(42)arguments?); // print statement179⟶true or false

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 1030 print("Hello"arguments?)1031 variable aname? set to 3value or expression?1032 variable bname? set to 4value or expression?1033 print(a*barguments?)1034 print($"{a} times {b}) equals {a*b}"arguments?)1035 variable tname? set to (true, 42)value or expression?1036 print(t.item_0arguments?)1037 print(t.item_1arguments?)1038 end main
+def main() -> None: 1039 print("Hello"arguments?)1040 aname? = 3value or expression? # variable definition1041 bname? = 4value or expression? # variable definition1042 print(a*barguments?)1043 print(f"{a} times {b}) equals {a*b}"arguments?)1044 tname? = (True, 42)value or expression? # variable definition1045 print(t.item_0arguments?)1046 print(t.item_1arguments?)1047 # end main
+static void main() { 1048 Console.WriteLine("Hello"arguments?); // print statement1049 var aname? = 3value or expression?;1050 var bname? = 4value or expression?;1051 Console.WriteLine(a*barguments?); // print statement1052 Console.WriteLine($"{a} times {b}) equals {a*b}"arguments?); // print statement1053 var tname? = (true, 42)value or expression?;1054 Console.WriteLine(t.item_0arguments?); // print statement1055 Console.WriteLine(t.item_1arguments?); // print statement1056 } // end main
+Sub main() 1057 Console.WriteLine("Hello"arguments?) ' print statement1058 Dim aname? = 3value or expression? ' variable definition1059 Dim bname? = 4value or expression? ' variable definition1060 Console.WriteLine(a*barguments?) ' print statement1061 Console.WriteLine($"{a} times {b}) equals {a*b}"arguments?) ' print statement1062 Dim tname? = (True, 42)value or expression? ' variable definition1063 Console.WriteLine(t.item_0arguments?) ' print statement1064 Console.WriteLine(t.item_1arguments?) ' print statement1065 End Sub
+static void main() { 1066 System.out.println("Hello"arguments?); // print statement1067 var aname? = 3value or expression?;1068 var bname? = 4value or expression?;1069 System.out.println(a*barguments?); // print statement1070 System.out.println(String.format("% times %) equals %", a, b, a*b)arguments?); // print statement1071 var tname? = (true, 42)value or expression?;1072 System.out.println(t.item_0arguments?); // print statement1073 System.out.println(t.item_1arguments?); // print statement1074 } // 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 1075 call printTabprocedureName?(0, "Number"arguments?)1076 call printTabprocedureName?(10, "Square"arguments?)1077 call printTabprocedureName?(20, "Cube\n"arguments?)1078 +for iitem? in range(1, 11)source? 1079 call printTabprocedureName?(0, i.toString()arguments?)1080 call printTabprocedureName?(10, $"{pow(i, 2)}"arguments?)1081 call printTabprocedureName?(20, $"{pow(i, 3)}\n"arguments?)1082 end for end main
+def main() -> None: 1083 printTabprocedureName?(0, "Number"arguments?) # procedure call1084 printTabprocedureName?(10, "Square"arguments?) # procedure call1085 printTabprocedureName?(20, "Cube\n"arguments?) # procedure call1086 +for iitem? in range(1, 11)source?: 1087 printTabprocedureName?(0, i.toString()arguments?) # procedure call1088 printTabprocedureName?(10, f"{pow(i, 2)}"arguments?) # procedure call1089 printTabprocedureName?(20, f"{pow(i, 3)}\n"arguments?) # procedure call1090 # end for # end main
+static void main() { 1091 printTabprocedureName?(0, "Number"arguments?); // procedure call1092 printTabprocedureName?(10, "Square"arguments?); // procedure call1093 printTabprocedureName?(20, "Cube\n"arguments?); // procedure call1094 +foreach (var iitem? in range(1, 11)source?) { 1095 printTabprocedureName?(0, i.toString()arguments?); // procedure call1096 printTabprocedureName?(10, $"{pow(i, 2)}"arguments?); // procedure call1097 printTabprocedureName?(20, $"{pow(i, 3)}\n"arguments?); // procedure call1098 } // end foreach } // end main
+Sub main() 1099 printTabprocedureName?(0, "Number"arguments?) ' procedure call1100 printTabprocedureName?(10, "Square"arguments?) ' procedure call1101 printTabprocedureName?(20, "Cube\n"arguments?) ' procedure call1102 +For Each iitem? In range(1, 11)source? 1103 printTabprocedureName?(0, i.toString()arguments?) ' procedure call1104 printTabprocedureName?(10, $"{pow(i, 2)}"arguments?) ' procedure call1105 printTabprocedureName?(20, $"{pow(i, 3)}\n"arguments?) ' procedure call1106 Next i End Sub
+static void main() { 1107 printTabprocedureName?(0, "Number"arguments?); // procedure call1108 printTabprocedureName?(10, "Square"arguments?); // procedure call1109 printTabprocedureName?(20, "Cube\n"arguments?); // procedure call1110 +foreach (var iitem? in range(1, 11)source?) { 1111 printTabprocedureName?(0, i.toString()arguments?); // procedure call1112 printTabprocedureName?(10, String.format("%", pow(i, 2))arguments?); // procedure call1113 printTabprocedureName?(20, String.format("%\n", pow(i, 3))arguments?); // procedure call1114 } // end foreach } // end main

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

main
main
main
main
main

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 a reassign 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.

system
method		 argument
types		 return
types		 returns
sFloat StringstrstringStringString FloatfloatdoubleDoubledouble Will throw an exception if the string does not parse as an integer
asInt StringstrstringStringString IntintintIntegerint Will throw an exception if the string does not parse as an integer
unicode IntintintIntegerint StringstrstringStringString a string containing the one character defined at the given Unicode code point

Examples using standalone functions

   ● Deconstructing the 2-Tuple returned by parseAsInt:

variable successname? set to parseAsInt(s).item_0value or expression?180successname? = parseAsInt(s).item_0value or expression? # variable definition181var successname? = parseAsInt(s).item_0value or expression?;182Dim successname? = parseAsInt(s).item_0value or expression? ' variable definition183var successname? = parseAsInt(s).item_0value or expression?;184 variable valuename? set to parseAsInt(s).item_1value or expression?185valuename? = parseAsInt(s).item_1value or expression? # variable definition186var valuename? = parseAsInt(s).item_1value or expression?;187Dim valuename? = parseAsInt(s).item_1value or expression? ' variable definition188var valuename? = parseAsInt(s).item_1value or expression?;189

Always check the BooleanboolboolBooleanboolean (successsuccesssuccesssuccesssuccess) before using the returned value (valuevaluevaluevaluevalue) in case the latter is zero only because the parse was unsuccessful.

   ● Test assertions that use methods parseAsInt and parseAsFloat:

+test test_parsetest_name? 1115 assert parseAsInt("31")actual (computed) value? is (true, 31)expected value? not run1116 assert parseAsInt("0")actual (computed) value? is (true, 0)expected value? not run1117 assert parseAsInt("thirty one")actual (computed) value? is (false, 0)expected value? not run1118 assert parseAsInt("3.1")actual (computed) value? is (false, 0)expected value? not run1119 assert parseAsFloat("31")actual (computed) value? is (true, 31)expected value? not run1120 assert parseAsFloat("0")actual (computed) value? is (true, 0)expected value? not run1121 assert parseAsFloat("3.1")actual (computed) value? is (true, 3.1)expected value? not run1122 end test
+class Test_parse(unittest.TestCase):
 def test_parsetest_name?(self) -> None: 1123 self.assertEqual(parseAsInt("31")actual (computed) value?, (True, 31)expected value?) not run1124 self.assertEqual(parseAsInt("0")actual (computed) value?, (True, 0)expected value?) not run1125 self.assertEqual(parseAsInt("thirty one")actual (computed) value?, (False, 0)expected value?) not run1126 self.assertEqual(parseAsInt("3.1")actual (computed) value?, (False, 0)expected value?) not run1127 self.assertEqual(parseAsFloat("31")actual (computed) value?, (True, 31)expected value?) not run1128 self.assertEqual(parseAsFloat("0")actual (computed) value?, (True, 0)expected value?) not run1129 self.assertEqual(parseAsFloat("3.1")actual (computed) value?, (True, 3.1)expected value?) not run1130 # end test
+[TestClass] class Test_parse
[TestMethod] static void test_parsetest_name?() { 1131 Assert.AreEqual((true, 31)expected value?, parseAsInt("31")actual (computed) value?); not run1132 Assert.AreEqual((true, 0)expected value?, parseAsInt("0")actual (computed) value?); not run1133 Assert.AreEqual((false, 0)expected value?, parseAsInt("thirty one")actual (computed) value?); not run1134 Assert.AreEqual((false, 0)expected value?, parseAsInt("3.1")actual (computed) value?); not run1135 Assert.AreEqual((true, 31)expected value?, parseAsFloat("31")actual (computed) value?); not run1136 Assert.AreEqual((true, 0)expected value?, parseAsFloat("0")actual (computed) value?); not run1137 Assert.AreEqual((true, 3.1)expected value?, parseAsFloat("3.1")actual (computed) value?); not run1138 }} // end test
+<TestClass Class Test_parse
 <TestMethod> Sub test_parsetest_name?() 1139 Assert.AreEqual((True, 31)expected value?, parseAsInt("31")actual (computed) value?) not run1140 Assert.AreEqual((True, 0)expected value?, parseAsInt("0")actual (computed) value?) not run1141 Assert.AreEqual((False, 0)expected value?, parseAsInt("thirty one")actual (computed) value?) not run1142 Assert.AreEqual((False, 0)expected value?, parseAsInt("3.1")actual (computed) value?) not run1143 Assert.AreEqual((True, 31)expected value?, parseAsFloat("31")actual (computed) value?) not run1144 Assert.AreEqual((True, 0)expected value?, parseAsFloat("0")actual (computed) value?) not run1145 Assert.AreEqual((True, 3.1)expected value?, parseAsFloat("3.1")actual (computed) value?) not run1146  End Sub
End Class
+class Test_parse {
@Test static void test_parsetest_name?() { 1147 assertEquals((true, 31)expected value?, parseAsInt("31")actual (computed) value?); not run1148 assertEquals((true, 0)expected value?, parseAsInt("0")actual (computed) value?); not run1149 assertEquals((false, 0)expected value?, parseAsInt("thirty one")actual (computed) value?); not run1150 assertEquals((false, 0)expected value?, parseAsInt("3.1")actual (computed) value?); not run1151 assertEquals((true, 31)expected value?, parseAsFloat("31")actual (computed) value?); not run1152 assertEquals((true, 0)expected value?, parseAsFloat("0")actual (computed) value?); not run1153 assertEquals((true, 3.1)expected value?, parseAsFloat("3.1")actual (computed) value?); not run1154 }} // end test
Notes

   ● Using method unicode:

print(unicode(0x2665)arguments?)190print(unicode(0x2665)arguments?)191Console.WriteLine(unicode(0x2665)arguments?); // print statement192Console.WriteLine(unicode(&H2665)arguments?) ' print statement193System.out.println(unicode(0x2665)arguments?); // print statement194⟶♥

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? 1155 assert piactual (computed) value? is 3.141592653589793expected value? not run1156 assert abs(-3.7)actual (computed) value? is 3.7expected value? not run1157 assert pow(2, 10)actual (computed) value? is 1024expected value? not run1158 assert sqrt(2).round(3)actual (computed) value? is 1.414expected value? not run1159 assert asin(0.5).round(3)actual (computed) value? is 0.524expected value? not run1160 assert acos(0.5).round(3)actual (computed) value? is 1.047expected value? not run1161 assert atan(1).round(2)actual (computed) value? is 0.79expected value? not run1162 assert sin(pi/6).round(2)actual (computed) value? is 0.5expected value? not run1163 assert cos(pi/4).round(3)actual (computed) value? is 0.707expected value? not run1164 assert tan(pi/4).round(2)actual (computed) value? is 1expected value? not run1165 assert exp(2).round(3)actual (computed) value? is 7.389expected value? not run1166 assert logE(7.389).round(2)actual (computed) value? is 2expected value? not run1167 assert log10(1000)actual (computed) value? is 3expected value? not run1168 assert log2(65536)actual (computed) value? is 16expected value? not run1169 assert log2(0x10000)actual (computed) value? is 16expected value? not run1170 end test
+class Test_maths(unittest.TestCase):
 def test_mathstest_name?(self) -> None: 1171 self.assertEqual(piactual (computed) value?, 3.141592653589793expected value?) not run1172 self.assertEqual(abs(-3.7)actual (computed) value?, 3.7expected value?) not run1173 self.assertEqual(pow(2, 10)actual (computed) value?, 1024expected value?) not run1174 self.assertEqual(sqrt(2).round(3)actual (computed) value?, 1.414expected value?) not run1175 self.assertEqual(asin(0.5).round(3)actual (computed) value?, 0.524expected value?) not run1176 self.assertEqual(acos(0.5).round(3)actual (computed) value?, 1.047expected value?) not run1177 self.assertEqual(atan(1).round(2)actual (computed) value?, 0.79expected value?) not run1178 self.assertEqual(sin(pi/6).round(2)actual (computed) value?, 0.5expected value?) not run1179 self.assertEqual(cos(pi/4).round(3)actual (computed) value?, 0.707expected value?) not run1180 self.assertEqual(tan(pi/4).round(2)actual (computed) value?, 1expected value?) not run1181 self.assertEqual(exp(2).round(3)actual (computed) value?, 7.389expected value?) not run1182 self.assertEqual(logE(7.389).round(2)actual (computed) value?, 2expected value?) not run1183 self.assertEqual(log10(1000)actual (computed) value?, 3expected value?) not run1184 self.assertEqual(log2(65536)actual (computed) value?, 16expected value?) not run1185 self.assertEqual(log2(0x10000)actual (computed) value?, 16expected value?) not run1186 # end test
+[TestClass] class Test_maths
[TestMethod] static void test_mathstest_name?() { 1187 Assert.AreEqual(3.141592653589793expected value?, piactual (computed) value?); not run1188 Assert.AreEqual(3.7expected value?, abs(-3.7)actual (computed) value?); not run1189 Assert.AreEqual(1024expected value?, pow(2, 10)actual (computed) value?); not run1190 Assert.AreEqual(1.414expected value?, sqrt(2).round(3)actual (computed) value?); not run1191 Assert.AreEqual(0.524expected value?, asin(0.5).round(3)actual (computed) value?); not run1192 Assert.AreEqual(1.047expected value?, acos(0.5).round(3)actual (computed) value?); not run1193 Assert.AreEqual(0.79expected value?, atan(1).round(2)actual (computed) value?); not run1194 Assert.AreEqual(0.5expected value?, sin(pi/6).round(2)actual (computed) value?); not run1195 Assert.AreEqual(0.707expected value?, cos(pi/4).round(3)actual (computed) value?); not run1196 Assert.AreEqual(1expected value?, tan(pi/4).round(2)actual (computed) value?); not run1197 Assert.AreEqual(7.389expected value?, exp(2).round(3)actual (computed) value?); not run1198 Assert.AreEqual(2expected value?, logE(7.389).round(2)actual (computed) value?); not run1199 Assert.AreEqual(3expected value?, log10(1000)actual (computed) value?); not run1200 Assert.AreEqual(16expected value?, log2(65536)actual (computed) value?); not run1201 Assert.AreEqual(16expected value?, log2(0x10000)actual (computed) value?); not run1202 }} // end test
+<TestClass Class Test_maths
 <TestMethod> Sub test_mathstest_name?() 1203 Assert.AreEqual(3.141592653589793expected value?, piactual (computed) value?) not run1204 Assert.AreEqual(3.7expected value?, abs(-3.7)actual (computed) value?) not run1205 Assert.AreEqual(1024expected value?, pow(2, 10)actual (computed) value?) not run1206 Assert.AreEqual(1.414expected value?, sqrt(2).round(3)actual (computed) value?) not run1207 Assert.AreEqual(0.524expected value?, asin(0.5).round(3)actual (computed) value?) not run1208 Assert.AreEqual(1.047expected value?, acos(0.5).round(3)actual (computed) value?) not run1209 Assert.AreEqual(0.79expected value?, atan(1).round(2)actual (computed) value?) not run1210 Assert.AreEqual(0.5expected value?, sin(pi/6).round(2)actual (computed) value?) not run1211 Assert.AreEqual(0.707expected value?, cos(pi/4).round(3)actual (computed) value?) not run1212 Assert.AreEqual(1expected value?, tan(pi/4).round(2)actual (computed) value?) not run1213 Assert.AreEqual(7.389expected value?, exp(2).round(3)actual (computed) value?) not run1214 Assert.AreEqual(2expected value?, logE(7.389).round(2)actual (computed) value?) not run1215 Assert.AreEqual(3expected value?, log10(1000)actual (computed) value?) not run1216 Assert.AreEqual(16expected value?, log2(65536)actual (computed) value?) not run1217 Assert.AreEqual(16expected value?, log2(&H10000)actual (computed) value?) not run1218  End Sub
End Class
+class Test_maths {
@Test static void test_mathstest_name?() { 1219 assertEquals(3.141592653589793expected value?, piactual (computed) value?); not run1220 assertEquals(3.7expected value?, abs(-3.7)actual (computed) value?); not run1221 assertEquals(1024expected value?, pow(2, 10)actual (computed) value?); not run1222 assertEquals(1.414expected value?, sqrt(2).round(3)actual (computed) value?); not run1223 assertEquals(0.524expected value?, asin(0.5).round(3)actual (computed) value?); not run1224 assertEquals(1.047expected value?, acos(0.5).round(3)actual (computed) value?); not run1225 assertEquals(0.79expected value?, atan(1).round(2)actual (computed) value?); not run1226 assertEquals(0.5expected value?, sin(pi/6).round(2)actual (computed) value?); not run1227 assertEquals(0.707expected value?, cos(pi/4).round(3)actual (computed) value?); not run1228 assertEquals(1expected value?, tan(pi/4).round(2)actual (computed) value?); not run1229 assertEquals(7.389expected value?, exp(2).round(3)actual (computed) value?); not run1230 assertEquals(2expected value?, logE(7.389).round(2)actual (computed) value?); not run1231 assertEquals(3expected value?, log10(1000)actual (computed) value?); not run1232 assertEquals(16expected value?, log2(65536)actual (computed) value?); not run1233 assertEquals(16expected value?, log2(0x10000)actual (computed) value?); not run1234 }} // 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? 1235 variable aname? set to 13value or expression?1236 assert aactual (computed) value? is 0xdexpected value? not run1237 assert aactual (computed) value? is 0b1101expected value? not run1238 assert a.asBinary()actual (computed) value? is "1101"expected value? not run1239 variable bname? set to 30value or expression?1240 assert bactual (computed) value? is 0b11110expected value? not run1241 assert bitAnd(a, b)actual (computed) value? is 0b1100expected value? not run1242 variable aobname? set to bitOr(a, b)value or expression?1243 assert aobactual (computed) value? is 0b11111expected value? not run1244 variable axbname? set to bitXor(a, b)value or expression?1245 assert axbactual (computed) value? is 0b10011expected value? not run1246 variable notaname? set to bitNot(a)value or expression?1247 assert notaactual (computed) value? is -14expected value? not run1248 variable aLname? set to bitShiftL(a, 2)value or expression?1249 assert aLactual (computed) value? is 0b110100expected value? not run1250 assert bitShiftR(a, 2)actual (computed) value? is 0b11expected value? not run1251 end test
+class Test_bitwise(unittest.TestCase):
 def test_bitwisetest_name?(self) -> None: 1252 aname? = 13value or expression? # variable definition1253 self.assertEqual(aactual (computed) value?, 0xdexpected value?) not run1254 self.assertEqual(aactual (computed) value?, 0b1101expected value?) not run1255 self.assertEqual(a.asBinary()actual (computed) value?, "1101"expected value?) not run1256 bname? = 30value or expression? # variable definition1257 self.assertEqual(bactual (computed) value?, 0b11110expected value?) not run1258 self.assertEqual(bitAnd(a, b)actual (computed) value?, 0b1100expected value?) not run1259 aobname? = bitOr(a, b)value or expression? # variable definition1260 self.assertEqual(aobactual (computed) value?, 0b11111expected value?) not run1261 axbname? = bitXor(a, b)value or expression? # variable definition1262 self.assertEqual(axbactual (computed) value?, 0b10011expected value?) not run1263 notaname? = bitNot(a)value or expression? # variable definition1264 self.assertEqual(notaactual (computed) value?, -14expected value?) not run1265 aLname? = bitShiftL(a, 2)value or expression? # variable definition1266 self.assertEqual(aLactual (computed) value?, 0b110100expected value?) not run1267 self.assertEqual(bitShiftR(a, 2)actual (computed) value?, 0b11expected value?) not run1268 # end test
+[TestClass] class Test_bitwise
[TestMethod] static void test_bitwisetest_name?() { 1269 var aname? = 13value or expression?;1270 Assert.AreEqual(0xdexpected value?, aactual (computed) value?); not run1271 Assert.AreEqual(0b1101expected value?, aactual (computed) value?); not run1272 Assert.AreEqual("1101"expected value?, a.asBinary()actual (computed) value?); not run1273 var bname? = 30value or expression?;1274 Assert.AreEqual(0b11110expected value?, bactual (computed) value?); not run1275 Assert.AreEqual(0b1100expected value?, bitAnd(a, b)actual (computed) value?); not run1276 var aobname? = bitOr(a, b)value or expression?;1277 Assert.AreEqual(0b11111expected value?, aobactual (computed) value?); not run1278 var axbname? = bitXor(a, b)value or expression?;1279 Assert.AreEqual(0b10011expected value?, axbactual (computed) value?); not run1280 var notaname? = bitNot(a)value or expression?;1281 Assert.AreEqual(-14expected value?, notaactual (computed) value?); not run1282 var aLname? = bitShiftL(a, 2)value or expression?;1283 Assert.AreEqual(0b110100expected value?, aLactual (computed) value?); not run1284 Assert.AreEqual(0b11expected value?, bitShiftR(a, 2)actual (computed) value?); not run1285 }} // end test
+<TestClass Class Test_bitwise
 <TestMethod> Sub test_bitwisetest_name?() 1286 Dim aname? = 13value or expression? ' variable definition1287 Assert.AreEqual(&Hdexpected value?, aactual (computed) value?) not run1288 Assert.AreEqual(&B1101expected value?, aactual (computed) value?) not run1289 Assert.AreEqual("1101"expected value?, a.asBinary()actual (computed) value?) not run1290 Dim bname? = 30value or expression? ' variable definition1291 Assert.AreEqual(&B11110expected value?, bactual (computed) value?) not run1292 Assert.AreEqual(&B1100expected value?, bitAnd(a, b)actual (computed) value?) not run1293 Dim aobname? = bitOr(a, b)value or expression? ' variable definition1294 Assert.AreEqual(&B11111expected value?, aobactual (computed) value?) not run1295 Dim axbname? = bitXor(a, b)value or expression? ' variable definition1296 Assert.AreEqual(&B10011expected value?, axbactual (computed) value?) not run1297 Dim notaname? = bitNot(a)value or expression? ' variable definition1298 Assert.AreEqual(-14expected value?, notaactual (computed) value?) not run1299 Dim aLname? = bitShiftL(a, 2)value or expression? ' variable definition1300 Assert.AreEqual(&B110100expected value?, aLactual (computed) value?) not run1301 Assert.AreEqual(&B11expected value?, bitShiftR(a, 2)actual (computed) value?) not run1302  End Sub
End Class
+class Test_bitwise {
@Test static void test_bitwisetest_name?() { 1303 var aname? = 13value or expression?;1304 assertEquals(0xdexpected value?, aactual (computed) value?); not run1305 assertEquals(0b1101expected value?, aactual (computed) value?); not run1306 assertEquals("1101"expected value?, a.asBinary()actual (computed) value?); not run1307 var bname? = 30value or expression?;1308 assertEquals(0b11110expected value?, bactual (computed) value?); not run1309 assertEquals(0b1100expected value?, bitAnd(a, b)actual (computed) value?); not run1310 var aobname? = bitOr(a, b)value or expression?;1311 assertEquals(0b11111expected value?, aobactual (computed) value?); not run1312 var axbname? = bitXor(a, b)value or expression?;1313 assertEquals(0b10011expected value?, axbactual (computed) value?); not run1314 var notaname? = bitNot(a)value or expression?;1315 assertEquals(-14expected value?, notaactual (computed) value?); not run1316 var aLname? = bitShiftL(a, 2)value or expression?;1317 assertEquals(0b110100expected value?, aLactual (computed) value?); not run1318 assertEquals(0b11expected value?, bitShiftR(a, 2)actual (computed) value?); not run1319 }} // 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? 1320 variable s1name? set to "hello"value or expression?1321 variable s2name? set to "World"value or expression?1322 variable rname? set to /^[a-z]*$/value or expression?1323 assert s1.matchesRegExp(r)actual (computed) value? is trueexpected value? not run1324 assert s2.matchesRegExp(r)actual (computed) value? is falseexpected value? not run1325 end test
+class Test_matchesRegExp(unittest.TestCase):
 def test_matchesRegExptest_name?(self) -> None: 1326 s1name? = "hello"value or expression? # variable definition1327 s2name? = "World"value or expression? # variable definition1328 rname? = /^[a-z]*$/value or expression? # variable definition1329 self.assertEqual(s1.matchesRegExp(r)actual (computed) value?, Trueexpected value?) not run1330 self.assertEqual(s2.matchesRegExp(r)actual (computed) value?, Falseexpected value?) not run1331 # end test
+[TestClass] class Test_matchesRegExp
[TestMethod] static void test_matchesRegExptest_name?() { 1332 var s1name? = "hello"value or expression?;1333 var s2name? = "World"value or expression?;1334 var rname? = /^[a-z]*$/value or expression?;1335 Assert.AreEqual(trueexpected value?, s1.matchesRegExp(r)actual (computed) value?); not run1336 Assert.AreEqual(falseexpected value?, s2.matchesRegExp(r)actual (computed) value?); not run1337 }} // end test
+<TestClass Class Test_matchesRegExp
 <TestMethod> Sub test_matchesRegExptest_name?() 1338 Dim s1name? = "hello"value or expression? ' variable definition1339 Dim s2name? = "World"value or expression? ' variable definition1340 Dim rname? = /^(a-z)*$/value or expression? ' variable definition1341 Assert.AreEqual(Trueexpected value?, s1.matchesRegExp(r)actual (computed) value?) not run1342 Assert.AreEqual(Falseexpected value?, s2.matchesRegExp(r)actual (computed) value?) not run1343  End Sub
End Class
+class Test_matchesRegExp {
@Test static void test_matchesRegExptest_name?() { 1344 var s1name? = "hello"value or expression?;1345 var s2name? = "World"value or expression?;1346 var rname? = /^[a-z]*$/value or expression?;1347 assertEquals(trueexpected value?, s1.matchesRegExp(r)actual (computed) value?); not run1348 assertEquals(falseexpected value?, s2.matchesRegExp(r)actual (computed) value?); not run1349 }} // end test

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

+test test_matchesRegExptest_name? 1350 variable s1name? set to "hello"value or expression?1351 variable s2name? set to "World"value or expression?1352 variable rname? set to "^[a-z]*$".asRegExp()value or expression?1353 assert s1.matchesRegExp(r)actual (computed) value? is trueexpected value? not run1354 assert s2.matchesRegExp(r)actual (computed) value? is falseexpected value? not run1355 end test
+class Test_matchesRegExp(unittest.TestCase):
 def test_matchesRegExptest_name?(self) -> None: 1356 s1name? = "hello"value or expression? # variable definition1357 s2name? = "World"value or expression? # variable definition1358 rname? = "^[a-z]*$".asRegExp()value or expression? # variable definition1359 self.assertEqual(s1.matchesRegExp(r)actual (computed) value?, Trueexpected value?) not run1360 self.assertEqual(s2.matchesRegExp(r)actual (computed) value?, Falseexpected value?) not run1361 # end test
+[TestClass] class Test_matchesRegExp
[TestMethod] static void test_matchesRegExptest_name?() { 1362 var s1name? = "hello"value or expression?;1363 var s2name? = "World"value or expression?;1364 var rname? = "^[a-z]*$".asRegExp()value or expression?;1365 Assert.AreEqual(trueexpected value?, s1.matchesRegExp(r)actual (computed) value?); not run1366 Assert.AreEqual(falseexpected value?, s2.matchesRegExp(r)actual (computed) value?); not run1367 }} // end test
+<TestClass Class Test_matchesRegExp
 <TestMethod> Sub test_matchesRegExptest_name?() 1368 Dim s1name? = "hello"value or expression? ' variable definition1369 Dim s2name? = "World"value or expression? ' variable definition1370 Dim rname? = "^(a-z)*$".asRegExp()value or expression? ' variable definition1371 Assert.AreEqual(Trueexpected value?, s1.matchesRegExp(r)actual (computed) value?) not run1372 Assert.AreEqual(Falseexpected value?, s2.matchesRegExp(r)actual (computed) value?) not run1373  End Sub
End Class
+class Test_matchesRegExp {
@Test static void test_matchesRegExptest_name?() { 1374 var s1name? = "hello"value or expression?;1375 var s2name? = "World"value or expression?;1376 var rname? = "^[a-z]*$".asRegExp()value or expression?;1377 assertEquals(trueexpected value?, s1.matchesRegExp(r)actual (computed) value?); not run1378 assertEquals(falseexpected value?, s2.matchesRegExp(r)actual (computed) value?); not run1379 }} // 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 and random numbers

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 type RandomRandomRandomRandomRandom .
system
method		 argument
types		 return
types		 returns
clock (none) IntintintIntegerint the current value (in milliseconds) of a system clock.
Useful for measuring elapsed time by comparing the values returned by two calls
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

System functions

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

system
method		 argument
types		 return
types		 returns
copy named value of any type same type as argument a copy of the named value
createDictionary ListlistListListList of 2-tuples, each containg a key:value pair Dictionary<of KeyType, ValueType>Dictionary[KeyType, ValueType]Dictionary<KeyType, ValueType>Dictionary(Of KeyType, ValueType)Dictionary<KeyType, ValueType> a Dictionary containing the specified key:value pairs
createPopulatedList IntintintIntegerint,
value of ListlistListListList item's type		 List<of ItemType>list[ItemType]List<ItemType>List(Of ItemType)List<ItemType> a List containing the specified number of items each initialised to the value in the second argument
createPopulatedListofLists IntintintIntegerint, IntintintIntegerint,
value of ListlistListListList item's type		 List<of List<of ItemType>>list[list[ItemType]]List<List<ItemType>>List(Of List(Of ItemType))List<List<ItemType>> a List of length the first argument containing that number of Lists
each initialised to a List 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 List
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 List
range IntintintIntegerint, IntintintIntegerint ListlistListListList a List 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 List is returned
rangeInSteps IntintintIntegerint, IntintintIntegerint, IntintintIntegerint ListlistListListList a List 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

Examples using range or rangeInSteps

   ● Print every second item in a List:

+main 1380 variable numbersname? set to ["zero", "one", "two", "three", "four", "five", "six"]value or expression?1381 +for nitem? in rangeInSteps(0, numbers.length() + 1, 2)source? 1382 print(numbers[n]arguments?)1383 end for end main
+def main() -> None: 1384 numbersname? = ["zero", "one", "two", "three", "four", "five", "six"]value or expression? # variable definition1385 +for nitem? in rangeInSteps(0, numbers.length() + 1, 2)source?: 1386 print(numbers[n]arguments?)1387 # end for # end main
+static void main() { 1388 var numbersname? = new [] {"zero", "one", "two", "three", "four", "five", "six"}value or expression?;1389 +foreach (var nitem? in rangeInSteps(0, numbers.length() + 1, 2)source?) { 1390 Console.WriteLine(numbers[n]arguments?); // print statement1391 } // end foreach } // end main
+Sub main() 1392 Dim numbersname? = {"zero", "one", "two", "three", "four", "five", "six"}value or expression? ' variable definition1393 +For Each nitem? In rangeInSteps(0, numbers.length() + 1, 2)source? 1394 Console.WriteLine(numbers(n)arguments?) ' print statement1395 Next n End Sub
+static void main() { 1396 var numbersname? = list("zero", "one", "two", "three", "four", "five", "six")value or expression?;1397 +foreach (var nitem? in rangeInSteps(0, numbers.length() + 1, 2)source?) { 1398 System.out.println(numbers[n]arguments?); // print statement1399 } // end foreach } // end main

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

+main 1400 print(primesFromList(range(2, 100))arguments?)1401 end main
+def main() -> None: 1402 print(primesFromList(range(2, 100))arguments?)1403 # end main
+static void main() { 1404 Console.WriteLine(primesFromList(range(2, 100))arguments?); // print statement1405 } // end main
+Sub main() 1406 Console.WriteLine(primesFromList(range(2, 100))arguments?) ' print statement1407 End Sub
+static void main() { 1408 System.out.println(primesFromList(range(2, 100))arguments?); // print statement1409 } // end main

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 list 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? 1410 variable matchesname? set to this.nodes.filter(lambda n as Node => n.point.equals(p))value or expression?1411 return if_(matches.length() is 1, matches.head(), emptyNode())value or expression?1412 end function
+def getNodeForname?(p: Pointparameter definitions?) -> NodeType?: # function1413 matchesname? = self.nodes.filter(lambda n: Node: n.point.equals(p))value or expression? # variable definition1414 return if_(matches.length() == 1, matches.head(), emptyNode())value or expression?1415 # end function
+static NodeType? getNodeForname?(Point pparameter definitions?) { // function1416 var matchesname? = this.nodes.filter(Node n => n.point.equals(p))value or expression?;1417 return if_(matches.length() == 1, matches.head(), emptyNode())value or expression?;1418 } // end function
+Function getNodeForname?(p As Pointparameter definitions?) As NodeType? 1419 Dim matchesname? = Me.nodes.filter(Function (n As Node) n.point.equals(p))value or expression? ' variable definition1420 Return if_(matches.length() = 1, matches.head(), emptyNode())value or expression?1421 End Function
+static NodeType? getNodeForname?(Point pparameter definitions?) { // function1422 var matchesname? = this.nodes.filter((Node n) -> n.point.equals(p))value or expression?;1423 return if_(matches.length() == 1, matches.head(), emptyNode())value or expression?;1424 } // end function

map

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

Examples using map

   ● To cube each integer value in a list:

+main 1425 variable liname? set to [1, 2, 3, 4, 5]value or expression?1426 print(li.map(lambda n as Int => pow(n, 3))arguments?)1427 end main
+def main() -> None: 1428 liname? = [1, 2, 3, 4, 5]value or expression? # variable definition1429 print(li.map(lambda n: int: pow(n, 3))arguments?)1430 # end main
+static void main() { 1431 var liname? = new [] {1, 2, 3, 4, 5}value or expression?;1432 Console.WriteLine(li.map(int n => pow(n, 3))arguments?); // print statement1433 } // end main
+Sub main() 1434 Dim liname? = {1, 2, 3, 4, 5}value or expression? ' variable definition1435 Console.WriteLine(li.map(Function (n As Integer) pow(n, 3))arguments?) ' print statement1436 End Sub
+static void main() { 1437 var liname? = list(1, 2, 3, 4, 5)value or expression?;1438 System.out.println(li.map((int n) -> pow(n, 3))arguments?); // print statement1439 } // 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 list to upper case:

+main 1440 variable namesname? set to ["Tom", "Dick", "Harriet"]value or expression?1441 print(names.map(lambda s as String => s.upperCase())arguments?)1442 end main
+def main() -> None: 1443 namesname? = ["Tom", "Dick", "Harriet"]value or expression? # variable definition1444 print(names.map(lambda s: str: s.upperCase())arguments?)1445 # end main
+static void main() { 1446 var namesname? = new [] {"Tom", "Dick", "Harriet"}value or expression?;1447 Console.WriteLine(names.map(string s => s.upperCase())arguments?); // print statement1448 } // end main
+Sub main() 1449 Dim namesname? = {"Tom", "Dick", "Harriet"}value or expression? ' variable definition1450 Console.WriteLine(names.map(Function (s As String) s.upperCase())arguments?) ' print statement1451 End Sub
+static void main() { 1452 var namesname? = list("Tom", "Dick", "Harriet")value or expression?;1453 System.out.println(names.map((String s) -> s.upperCase())arguments?); // print statement1454 } // end main


⟶

[TOM, DICK, HARRIET]

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

+main 1455 print(names.map(lambda s as String => reverse(s))arguments?)1456 end main
+def main() -> None: 1457 print(names.map(lambda s: str: reverse(s))arguments?)1458 # end main
+static void main() { 1459 Console.WriteLine(names.map(string s => reverse(s))arguments?); // print statement1460 } // end main
+Sub main() 1461 Console.WriteLine(names.map(Function (s As String) reverse(s))arguments?) ' print statement1462 End Sub
+static void main() { 1463 System.out.println(names.map((String s) -> reverse(s))arguments?); // print statement1464 } // end main

⟶
[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?1465
nname? = p.neighbouringPoints().map(lambda p: Point: getValue(p, g))value or expression? # variable definition1466
var nname? = p.neighbouringPoints().map(Point p => getValue(p, g))value or expression?;1467
Dim nname? = p.neighbouringPoints().map(Function (p As Point) getValue(p, g))value or expression? ' variable definition1468
var nname? = p.neighbouringPoints().map((Point p) -> getValue(p, g))value or expression?;1469

reduce

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

The result may, however, be of a different type than the items in the list, 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 list 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 list.

In other words, the specified function or lambdalambdalambdalambdalambda is applied to each item of the input List 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 1470 variable nname? set to [0.1, 2, 2.5, 0.3, 5.75, 0.29]value or expression?1471 print(n.reduce(0.0, lambda sum as Float, m as Float => (sum + m).round(2))arguments?)1472 end main
+def main() -> None: 1473 nname? = [0.1, 2, 2.5, 0.3, 5.75, 0.29]value or expression? # variable definition1474 print(n.reduce(0.0, lambda sum: float, m: float: (sum + m).round(2))arguments?)1475 # end main
+static void main() { 1476 var nname? = new [] {0.1, 2, 2.5, 0.3, 5.75, 0.29}value or expression?;1477 Console.WriteLine(n.reduce(0.0, double sum, double m => (sum + m).round(2))arguments?); // print statement1478 } // end main
+Sub main() 1479 Dim nname? = {0.1, 2, 2.5, 0.3, 5.75, 0.29}value or expression? ' variable definition1480 Console.WriteLine(n.reduce(0.0, Function (sum As Double, m As Double) (sum + m).round(2))arguments?) ' print statement1481 End Sub
+static void main() { 1482 var nname? = list(0.1, 2, 2.5, 0.3, 5.75, 0.29)value or expression?;1483 System.out.println(n.reduce(0.0, (double sum, double m) -> (sum + m).round(2))arguments?); // print statement1484 } // end main


⟶

10.9410.9410.9410.9410.94
   Notes

   ● To reverse the order of items in a ListlistListListList:

+main 1485 variable nname? set to [2, 3, 5, 7, 11, 13]value or expression?1486 variable nRname? set to new List<of Int>()value or expression?1487 variable eLname? set to new List<of Int>()value or expression?1488 print(n.reduce(eL, lambda nR as List<of Int>, m as Int => nR.withPrepend(m))arguments?)1489 end main
+def main() -> None: 1490 nname? = [2, 3, 5, 7, 11, 13]value or expression? # variable definition1491 nRname? = list[int]()value or expression? # variable definition1492 eLname? = list[int]()value or expression? # variable definition1493 print(n.reduce(eL, lambda nR: list[int], m: int: nR.withPrepend(m))arguments?)1494 # end main
+static void main() { 1495 var nname? = new [] {2, 3, 5, 7, 11, 13}value or expression?;1496 var nRname? = new List<int>()value or expression?;1497 var eLname? = new List<int>()value or expression?;1498 Console.WriteLine(n.reduce(eL, List<int> nR, int m => nR.withPrepend(m))arguments?); // print statement1499 } // end main
+Sub main() 1500 Dim nname? = {2, 3, 5, 7, 11, 13}value or expression? ' variable definition1501 Dim nRname? = New List(Of Integer)()value or expression? ' variable definition1502 Dim eLname? = New List(Of Integer)()value or expression? ' variable definition1503 Console.WriteLine(n.reduce(eL, Function (nR As List(Of Integer), m As Integer) nR.withPrepend(m))arguments?) ' print statement1504 End Sub
+static void main() { 1505 var nname? = list(2, 3, 5, 7, 11, 13)value or expression?;1506 var nRname? = new List<int>()value or expression?;1507 var eLname? = new List<int>()value or expression?;1508 System.out.println(n.reduce(eL, (List<int> nR, int m) -> nR.withPrepend(m))arguments?); // print statement1509 } // 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 1510 variable sname? set to "'Twas brillig and the slithy toves"value or expression?1511 variable sRname? set to ""value or expression?1512 variable eLname? set to new List<of String>()value or expression?1513 assign sRvariableName? to s.split(" ").reduce(eL, lambda sR as List<of String>, word as String => sR.withPrepend(word)).join(" ")value or expression?1514 print(sRarguments?)1515 end main
+def main() -> None: 1516 sname? = "'Twas brillig and the slithy toves"value or expression? # variable definition1517 sRname? = ""value or expression? # variable definition1518 eLname? = list[str]()value or expression? # variable definition1519 sRvariableName? = s.split(" ").reduce(eL, lambda sR: list[str], word: str: sR.withPrepend(word)).join(" ")value or expression? # assignment1520 print(sRarguments?)1521 # end main
+static void main() { 1522 var sname? = "'Twas brillig and the slithy toves"value or expression?;1523 var sRname? = ""value or expression?;1524 var eLname? = new List<string>()value or expression?;1525 sRvariableName? = s.split(" ").reduce(eL, List<string> sR, string word => sR.withPrepend(word)).join(" ")value or expression?; // assignment1526 Console.WriteLine(sRarguments?); // print statement1527 } // end main
+Sub main() 1528 Dim sname? = "'Twas brillig and the slithy toves"value or expression? ' variable definition1529 Dim sRname? = ""value or expression? ' variable definition1530 Dim eLname? = New List(Of String)()value or expression? ' variable definition1531 sRvariableName? = s.split(" ").reduce(eL, Function (sR As List(Of String), word As String) sR.withPrepend(word)).join(" ")value or expression? ' assignment1532 Console.WriteLine(sRarguments?) ' print statement1533 End Sub
+static void main() { 1534 var sname? = "'Twas brillig and the slithy toves"value or expression?;1535 var sRname? = ""value or expression?;1536 var eLname? = new List<String>()value or expression?;1537 sRvariableName? = s.split(" ").reduce(eL, (List<String> sR, String word) -> sR.withPrepend(word)).join(" ")value or expression?; // assignment1538 System.out.println(sRarguments?); // print statement1539 } // 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 list 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 list the integer that has the highest last digit:

+main 1540 variable aname? set to [33, 4, 0, 92, 89, 55, 102]value or expression?1541 print(a.maxBy(lambda x as Int => x mod 10)arguments?)1542 end main
+def main() -> None: 1543 aname? = [33, 4, 0, 92, 89, 55, 102]value or expression? # variable definition1544 print(a.maxBy(lambda x: int: x % 10)arguments?)1545 # end main
+static void main() { 1546 var aname? = new [] {33, 4, 0, 92, 89, 55, 102}value or expression?;1547 Console.WriteLine(a.maxBy(int x => x % 10)arguments?); // print statement1548 } // end main
+Sub main() 1549 Dim aname? = {33, 4, 0, 92, 89, 55, 102}value or expression? ' variable definition1550 Console.WriteLine(a.maxBy(Function (x As Integer) x Mod 10)arguments?) ' print statement1551 End Sub
+static void main() { 1552 var aname? = list(33, 4, 0, 92, 89, 55, 102)value or expression?;1553 System.out.println(a.maxBy((int x) -> x % 10)arguments?); // print statement1554 } // end main


⟶

8989898989

   ● To find in a list the the shortest string:

+main 1555 variable fruitname? set to ["apple", "orange", "pear"]value or expression?1556 print(fruit.minBy(lambda x as String => x.length())arguments?)1557 end main
+def main() -> None: 1558 fruitname? = ["apple", "orange", "pear"]value or expression? # variable definition1559 print(fruit.minBy(lambda x: str: x.length())arguments?)1560 # end main
+static void main() { 1561 var fruitname? = new [] {"apple", "orange", "pear"}value or expression?;1562 Console.WriteLine(fruit.minBy(string x => x.length())arguments?); // print statement1563 } // end main
+Sub main() 1564 Dim fruitname? = {"apple", "orange", "pear"}value or expression? ' variable definition1565 Console.WriteLine(fruit.minBy(Function (x As String) x.length())arguments?) ' print statement1566 End Sub
+static void main() { 1567 var fruitname? = list("apple", "orange", "pear")value or expression?;1568 System.out.println(fruit.minBy((String x) -> x.length())arguments?); // print statement1569 } // 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 list 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? 1570 let sumXname? be points.sumBy(lambda p as Point => p.x)value or expression?1571 let sumXsqname? be points.sumBy(lambda p as Point => p.x*p.x)value or expression?1572 let sumYname? be points.sumBy(lambda p as Point => p.y)value or expression?1573 let sumXYname? be points.sumBy(lambda p as Point => p.x*p.y)value or expression?1574 let nname? be points.length()value or expression?1575 let aname? be (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression?1576 let bname? be (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression?1577 return (a, b)value or expression?1578 end function
+def bestFitLinename?(points: list[Point]parameter definitions?) -> tuple[float, float]Type?: # function1579 sumXname? = points.sumBy(lambda p: Point: p.x)value or expression? # let1580 sumXsqname? = points.sumBy(lambda p: Point: p.x*p.x)value or expression? # let1581 sumYname? = points.sumBy(lambda p: Point: p.y)value or expression? # let1582 sumXYname? = points.sumBy(lambda p: Point: p.x*p.y)value or expression? # let1583 nname? = points.length()value or expression? # let1584 aname? = (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression? # let1585 bname? = (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression? # let1586 return (a, b)value or expression?1587 # end function
+static (double, double)Type? bestFitLinename?(List<Point> pointsparameter definitions?) { // function1588 var sumXname? = points.sumBy(Point p => p.x)value or expression?; // let1589 var sumXsqname? = points.sumBy(Point p => p.x*p.x)value or expression?; // let1590 var sumYname? = points.sumBy(Point p => p.y)value or expression?; // let1591 var sumXYname? = points.sumBy(Point p => p.x*p.y)value or expression?; // let1592 var nname? = points.length()value or expression?; // let1593 var aname? = (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression?; // let1594 var bname? = (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression?; // let1595 return (a, b)value or expression?;1596 } // end function
+Function bestFitLinename?(points As List(Of Point)parameter definitions?) As (Double, Double)Type? 1597 Dim sumXname? = points.sumBy(Function (p As Point) p.x)value or expression? ' let1598 Dim sumXsqname? = points.sumBy(Function (p As Point) p.x*p.x)value or expression? ' let1599 Dim sumYname? = points.sumBy(Function (p As Point) p.y)value or expression? ' let1600 Dim sumXYname? = points.sumBy(Function (p As Point) p.x*p.y)value or expression? ' let1601 Dim nname? = points.length()value or expression? ' let1602 Dim aname? = (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression? ' let1603 Dim bname? = (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression? ' let1604 Return (a, b)value or expression?1605 End Function
+static (double, double)Type? bestFitLinename?(List<Point> pointsparameter definitions?) { // function1606 var sumXname? = points.sumBy((Point p) -> p.x)value or expression?; // let1607 var sumXsqname? = points.sumBy((Point p) -> p.x*p.x)value or expression?; // let1608 var sumYname? = points.sumBy((Point p) -> p.y)value or expression?; // let1609 var sumXYname? = points.sumBy((Point p) -> p.x*p.y)value or expression?; // let1610 var nname? = points.length()value or expression?; // let1611 var aname? = (sumY*sumXsq - sumX*sumXY)/(n*sumXsq - sumX*sumX)value or expression?; // let1612 var bname? = (n*sumXY - sumX*sumY)/(n*sumXsq - sumX*sumX)value or expression?; // let1613 return (a, b)value or expression?;1614 } // 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):

variable numbersname? set to [27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23]value or expression?1615
numbersname? = [27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23]value or expression? # variable definition1616
var numbersname? = new [] {27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23}value or expression?;1617
Dim numbersname? = {27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23}value or expression? ' variable definition1618
var numbersname? = list(27, 2, 3, 5, 7, 31, 37, 11, 23, 13, 19, 23)value or expression?;1619
⟶
[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 1620 variable namesname? set to ["Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul"]value or expression?1621 print(names.orderBy(lambda x as String, y as String => x.isBefore(y))arguments?)1622 end main
+def main() -> None: 1623 namesname? = ["Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul"]value or expression? # variable definition1624 print(names.orderBy(lambda x: str, y: str: x.isBefore(y))arguments?)1625 # end main
+static void main() { 1626 var namesname? = new [] {"Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul"}value or expression?;1627 Console.WriteLine(names.orderBy(string x, string y => x.isBefore(y))arguments?); // print statement1628 } // end main
+Sub main() 1629 Dim namesname? = {"Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul"}value or expression? ' variable definition1630 Console.WriteLine(names.orderBy(Function (x As String, y As String) x.isBefore(y))arguments?) ' print statement1631 End Sub
+static void main() { 1632 var namesname? = list("Simon", "Pauline", "Jason", "Zelda", "Edith", "Lance", "Alice", "Paul")value or expression?;1633 System.out.println(names.orderBy((String x, String y) -> x.isBefore(y))arguments?); // print statement1634 } // 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?1635 property mathsPercentname? as IntType?1636 +constructor(parameter definitions?) 1637 new code end constructor +function toStringname?(parameter definitions?) returns StringType? 1638 return "undefined"value or expression?1639 end function end class
+class PupilName? inheritance?: # concrete class1640 mathsPercentname?: intType? # property1641 +def __init__(self: Pupil) -> None: 1642 new code # end constructor +def toStringname?(self: Pupil) -> strType?: # function method1643 return "undefined"value or expression?1644 # end function method # end class
+class PupilName? inheritance? {1645 public intType? mathsPercentname? {get; private set;} // property1646 +public Pupil(parameter definitions?) { 1647 new code } // end constructor +public stringType? toStringname?(parameter definitions?) { // function method1648 return "undefined"value or expression?;1649 } // end function method } // end class
+Class PupilName? inheritance?1650 Property mathsPercentname? As IntegerType?1651 +Sub New(parameter definitions?) 1652 new code End Sub +Function toStringname?(parameter definitions?) As StringType? 1653 Return "undefined"value or expression?1654 End Function End Class
+class PupilName? inheritance? {1655 public intType? mathsPercentname?; // property1656 +public Pupil(parameter definitions?) { 1657 new code } // end constructor +public StringType? toStringname?(parameter definitions?) { // function method1658 return "undefined"value or expression?;1659 } // end function method } // end class

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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