Re^5: Are monks hibernating?

[shmem]

Take a look at Perl's lousy showing in the recursive Benchmark for what I mean about subroutine/method performance.

Well, lousy verbose coding is a big issue here, too. Removing unnecessary allocation of variables and explicit return calls where possible, and replacing the named subs with coderefs

# The Computer Language Shootout
# http://shootout.alioth.debian.org/
# recursive test, by Andreas Koenig, Sep 24 2006

### Uses temp variables to help perl free memory earlier

use strict;
my($Ack,$Fib,$Tak);
$Ack = sub
{
        my ($x, $y) = @_;

        return $y + 1         if $x == 0;
        return $Ack->($x - 1, 1) if $y == 0;

        $Ack->($x - 1, $Ack->($x, $y - 1));
};

$Fib = sub
{
        my ($n) = @_;

        return 1 if $n < 2;

        $Fib->($n - 2) + $Fib->($n - 1);
};

$Tak = sub
{
        my ($x, $y, $z) = @_;
 
        if ($y < $x) {
          my $z1 = $Tak->($x - 1.0, $y, $z);
          my $z2 = $Tak->($y - 1.0, $z, $x);
          my $z3 = $Tak->($z - 1.0, $x, $y);
          return $Tak->($z1, $z2, $z3);
        } else {
          return $z;
        } 
};

my $n = ($ARGV[0] || 0) - 1;
printf "Ack(%d,%d): %d\n",
        3, $n + 1, $Ack->(3, $n + 1);
printf "Fib(%.1f): %.1f\n",
        28.0 + $n, $Fib->(28.0 + $n);
printf "Tak(%d,%d,%d): %d\n",
        $n * 3, $n * 2, $n, $Tak->($n * 3, $n * 2, $n);
printf "Fib(%d): %d\n", 
        3, $Fib->(3);
printf "Tak(%.1f,%.1f,%.1f): %.1f\n",
        3.0,2.0,1.0, $Tak->(3.0,2.0,1.0);

gives a speed gain of roughly 25% - that's still slower than python, though...

update: fixed wording

[BrowserUk]

Please see Re^4: Are monks hibernating?. I've posted another version of Ack() towards the end.