lyng/docs/Iterable.md

Iterable interface

Iterable is a class that provides function that creates the iterator:

class Iterable {
    abstract fun iterator()
}

Note that each call of iterator() must provide an independent iterator.

Iterator itself is a simple interface that should provide only to method:

class Iterator {
    abstract fun hasNext(): Bool
    fun next(): Obj
}

Just remember at this stage typed declarations are not yet supported.

Having Iterable in base classes allows to use it in for loop. Also, each Iterable has some utility functions available, for example

val r = 1..10  // Range is Iterable!  
assertEquals( [9,10] r.takeLast(2) )
assertEquals( [1,2,3] r.take(3) )
assertEquals( [9,10] r.drop(8) )
assertEquals( [1,2] r.dropLast(8) )
>>> void

Instance methods

fun/method	description
toList()	create a list from iterable
toSet()	create a set from iterable
contains(i)	check that iterable contains i
i in iterator	same as contains(i)
isEmpty()	check iterable is empty
forEach(f)	call f for each element
toMap()	create a map from list of key-value pairs (arrays of 2 items or like)
map(f)	create a list of values returned by f called for each element of the iterable
indexOf(i)	return index if the first encounter of i or a negative value if not found
associateBy(kf)	create a map where keys are returned by kf that will be called for each element
first	first element (1)
last	last element (1)
take(n)	return [Iterable] of up to n first elements
taleLast(n)	return [Iterable] of up to n last elements
drop(n)	return new [Iterable] without first n elements
dropLast(n)	return new [Iterable] without last n elements

(1)

throws NoSuchElementException if there is no such element

fun Iterable.toList(): List fun Iterable.toSet(): Set fun Iterable.indexOf(element): Int fun Iterable.contains(element): Bool fun Iterable.isEmpty(element): Bool fun Iterable.forEach(block: (Any?)->Void ): Void fun Iterable.map(block: (Any?)->Void ): List fun Iterable.associateBy( keyMaker: (Any?)->Any): Map

Abstract methods

fun iterator(): Iterator

Creates a list by iterating to the end. So, the Iterator should be finite to be used with it.

Included in interfaces:

• [Collection], Array, List

Implemented in classes:

• List, Range