#!perl -w
use strict;

my @set = qw(a b c);

my @tuples = mk_tuples(3, \@set);
for (@tuples) {
  print "(", join(", ", @$_), ")\n";
}
sub mk_tuples {
  my $n = shift;
  my $setr = shift;
  my $len = 0;
  my @result = ();
  my @hold = ();

  mk_tuples_r($n, $setr, \@hold, \@result);
  return @result;
}

sub mk_tuples_r {
  my ($n, $setr, $holdr, $resultr) = @_;
  my $len = 1 + @$holdr;
  for my $e (@$setr) {
    push @$holdr, $e;
    if ($len == $n) {
      push @$resultr, [ @$holdr ];
    } else {
      mk_tuples_r($n, $setr, $holdr, $resultr);
    }
    pop @$holdr;
  }
}
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