You probably know puzzles like this: use arithmetic operators and parenthesis to generate the number 24 using exactly the following four digits in any order: (1, 2, 4, 6) 1, 3, 4, 6.

I've written a ruby program to solve puzzles like this. The program works fine and gives the solution. However, when I translated this program to perl, I couldn't get it work. I've now even reformatted the two programs to be the same line by line (lay then side by side if that helps), but I still can't find out the problem.

I'd be grateful if you could look through the program (witha fresh mind) in any way and find the error. Thank you.

#!ruby -w
# alapm.rb -- megold egy számrejtvényt
# Állítsuk elő a 24-et alapműveletekkel az 1, 3, 4, 6 számjegyek ponto
+san 
# egyszeri felhasználásával.  A sorrend tetsz.









def mask \
    s, m; 
    (0 ... s.size).find_all {|k| 0 != m[k] }.map {|k| s[k] } 
end; 


def poss2 \
    v1, v2, s1, s2; program to solve puzzles like this.  The program w
+orks fine 
    yield v1 + v2, "(" + s1 + " + " + s2 + ")"; 
    yield v1 - v2, "(" + s1 + " - " + s2 + ")";
    yield v1 * v2, "(" + s1 + " * " + s2 + ")"; 
    1e-8 < v2.abs and 
        yield Float(v1) / v2, "(" + s1 + " / " + s2 + ")"; 
    s1 =~ /^\d+$/ && s2 =~ /^\d$/ and
        yield v1 + 10*v2, s1 + s2;
end;


def poss \
    v, s; 
    if 1 == v.size; 
        yield v.first, s.first;
    else 
        (1 ... (1<<v.size) - 1).each{|m| 
            vv2 = []; ss2 = [];
            poss(mask(v, ~m), mask(s, ~m)) {
                |v2, s2| 
                vv2.push v2;
                ss2.push s2; 
            };
            poss(mask(v, m), mask(s, m)) {
                |v1, s1|
                (0 ... vv2.size).each {|k|
                    poss2(v1, vv2[k], s1, ss2[k]) {
                        |v3, s3|
                        yield v3, s3;
                    };
                };
            };
        };
    end;
end; 


#

def main;
    poss(NUMS, NUMS.map{|x| x.to_s}) {
        |r, s| 
        (r - TARGET).abs < 1e-6 and
            print r, " = ", s, "\n"; 
    };
end;


NUMS = [1, 3, 4, 6]; 
TARGET = 24;
main;


__END__
[download]

#!perl
# alapm.pl -- megold egy számrejtvényt
# Rubyból fordítottam perlbe kábé szó szerint, tehát rosszabbnak kell 
# lennie, mintha eleve perlben írnám.  Látszik rajta, callbackeket 
# használok úgy, ahogy perl-ben nem tenném.
# Állítsuk elő a 24-et alapműveletekkel az 1, 3, 4, 6 számjegyek ponto
+san 
# egyszeri felhasználásával.  A sorrend tetsz.

use warnings;
use strict;
use Carp "cluck";


sub mask {
    my($s, $m) = @_;
    [map { $$s[$_] } grep { 0 != ($m & (1<<$_)) } 0 .. @$s - 1];
}


sub poss2 {
    my($v1, $v2, $s1, $s2, $f) = @_;
    &$f($v1 + $v2, "(" . $s1 . " + " . $s2 . ")");
    &$f($v1 - $v2, "(" . $s1 . " - " . $s2 . ")");
    &$f($v1 * $v2, "(" . $s1 . " * " . $s2 . ")");
    1e-8 < abs($v2) and
        &$f($v1 / $v2, "(" . $s1 . " / " . $s2 . ")");
    $s1 =~ /^\d+$/ && $s2 =~ /^\d$/ and
        &$f($v1 + 10 * $v2, $s1 + $s2);
}


sub poss {
    my($v, $s, $f) = @_;
    if (1 == @$v) {
        &$f($$v[0], $$s[0]);
    } else {
        for my $m (1 .. (1<<@$v) - 2) {
            my(@vv2, @ss2);
            poss(mask($v, ~$m), mask($s, ~$m), sub {
                my($v2, $s2) = @_;
                push @vv2, $v2;
                push @ss2, $s2;
            });
            poss(mask($v, $m), mask($s, $m), sub {
                my($v1, $s1) = @_;
                for my $k (0 .. @vv2 - 1) {
                    poss2($v1, $vv2[$k], $s1, $ss2[$k], sub {
                        my($v3, $s3) = @_;
                        &$f($v3, $s3);
                    });
                }
            });
        }
    }
}


my(@NUMS, $TARGET);

sub main {
    poss([@NUMS], [@NUMS], sub {
        my($r, $s) = @_;
        abs($r - $TARGET) < 1e-6 and
            print $r, " = ", $s, "\n";
    });
}


@NUMS = (1, 3, 4, 6);
$TARGET = 24;
main();


__END__
[download]

Update: as talexb notes, the description in the first paragraph has different digits then the code. I've corrected that.

The desired output of the code (and the real output of the ruby code) follows (I should have included this):