One-Pass Sorting Algorithm

TwoChannels.pl6

#!/usr/bin/env perl6
use v6;
sub sort-promise ($in, $out) {
   start {
      my @same;
      earliest $in {
         more * { push @same, $in.receive }
         done * { return }
      }
      my ($less_c, $more_c) = Channel.new xx 2;
      my ($less_p, $more_p) = map { sort-promise($_, $out) }, $less_c, $more_c;
      1 while do earliest $in {
        more * {
          given $_ <=> @same[0] {
            when Same { push @same, $_ }
            when Less { $less_c.send( $_ ) }
            when More { $more_c.send( $_ ) }
          }
          True;
        }
        done * { False }
      };
      $less_c.close; $less_p.result;
      $out.send for @same;
      $more_c.close; $more_p.result;
   }
}

my ($unsorted, $sorted) = Channel.new xx 2;
my $p = sort-promise( $unsorted, $sorted ).then({ $sorted.closed });
await $p, start {
  1 while do earliest $sorted {
    more * { .say; }
    done * { False }
  }, start {
    $unsorted.send(rand) for 1..20;
    $unsorted.close;
  };
};

say 'done';