lyng/docs/Array.md

Array

It's an interface if the Collection that provides indexing access, like array[3] = 0. Array therefore implements Iterable too. The well known implementatino of the Array is List.

Array adds the following methods:

Binary search

When applied to sorted arrays, binary search allow to quicly find an index of the element in the array, or where to insert it to keep order:

val coll = [1,2,3,4,5]
assertEquals( 2, coll.binarySearch(3) )
assertEquals( 0, coll.binarySearch(1) )
assertEquals( 4, coll.binarySearch(5) )

val src = (1..50).toList().shuffled()
val result = []
for( x in src ) {
    val i = result.binarySearch(x)
    assert( i < 0 )
    result.insertAt(-i-1, x)
}
assertEquals( src.sorted(), result )
>>> void

So binarySearch(x) returns:

• index of x, a non-negative number
• negative: x not found, but if inserted at position -returnedValue-1 will leave array sorted.

To pre-sort and array use Iterable.sorted* or in-place List.sort* families, see List and Iterable docs.