#!/usr/bin/env perl

use HOI::Comprehensions;
use HOI::Match;

sub slowsort {
    HOI::Match::pmatch(
        'nil' => sub { [] },
        'pivot :: unsorted' =>
        sub {
            my $left = HOI::Comprehensions::comp( sub { $x }, x => $unsorted )->( sub { $x <= $pivot } );
            my $right = HOI::Comprehensions::comp( sub { $x }, x => $unsorted )->( sub { $x > $pivot } );
            [ @{slowsort($left->force)}, $pivot, @{slowsort($right->force)} ]
        },
    )->(@_)
}

my $res = slowsort [3, 4, 1, 2, 5, 6];
print @$res, "\n";