Sort Using Supplies

SupplySort.pl6

#!/usr/bin/env perl6
use v6;
sub mysort( Supply $s ) {
  my (@same, @supplies, @promises);
  my $p = Promise.new;
  $s.tap( -> $val {
    if @same {
      given $val <=> @same[0] {
        when Same { push @same, $val }
        when Less { @supplies[0].emit( $val ) }
        when More { @supplies[1].emit( $val ) }
      }
    } else {
      push @same, $val;
      @supplies = Supply.new xx 2;
      @promises = map { mysort( $_ ) }, @supplies;
    }
  }, done => {
    if @same {
      .done for @supplies;
      $p.keep( [|@promises[0].result, |@same, |@promises[1].result] );
    } else {
      $p.keep( [] );
    }
  } );
  $p;
}

my $sort-supply = Supply.new;
my $sort-promise = mysort($sort-supply);
$sort-supply.emit($_) for (1..20).pick(*);
$sort-supply.done;
.say for $sort-promise.result;