P07 - Flatten a nested array structure.

Author: Johan Viklund

We use the gather/take structure.

A gather block builds a list using take statements. Each take adds one element to the list. The gather block returns the complete list.

A gather block operates with dynamic scope, so the take statements may be in another subroutine.

  • for @t -> $t

iterates over @t, placing each element in turn in $t

  • ~~

is the smart match operator. Here we use it to check the type of $t. we could have said $t.isa(Array) instead.


P07 (**) Flatten a nested array structure.
    Transform an array, possibly holding arrays as elements into a `flat'
    list by replacing each array with its elements (recursively).


> splat([1,[2,[3,4],5]]).perl.say;
(1, 2, 3, 4, 5)

Source code: P07-viklund.pl

use v6;

sub _splat(@t) {
    for @t -> $t {
        if $t ~~ Array { _splat($t) }
        else           { take $t }

sub splat (@t) { gather _splat(@t) }

splat([1, [2,[3,4], 5]]).list.perl.say;