gistfile1.pl

#!/usr/bin/env perl

use strict;
use warnings;

use Benchmark qw(cmpthese);

my $String = "ATGC" x 1000;
my @Genes = qw(A T G C);
my %Count;

cmpthese 10_000, {
    "eval_tr" => sub {
        for my $gene (@Genes) {
            $Count{$gene} += eval "\$String =~ tr/$gene//";
            die $@ if $@;
        }
    },
    "match" => sub {
        for my $gene (@Genes) {
            $Count{$gene} += () = $String =~ /$gene/g;
            die $@ if $@;
        }
    },
    "unrolled_tr" => sub {
        $Count{A} += $String =~ tr/A//;
        $Count{T} += $String =~ tr/T//;
        $Count{G} += $String =~ tr/G//;
        $Count{C} += $String =~ tr/C//;
    },
    "unrolled_match" => sub {
        $Count{A} += () = $String =~ /A/g;
        $Count{T} += () = $String =~ /T/g;
        $Count{G} += () = $String =~ /G/g;
        $Count{C} += () = $String =~ /C/g;
    },
};