Reimplementation of List::Util for running on perl 5.10

ListUtil.pm

#!/usr/bin/env perl
package ListUtil;
# Reimplementation of List::Util for running on perl 5.10
use strict;
use warnings;
use Exporter 'import';
@ListUtil::EXPORT_OK = qw(pairgrep pairmap pairkeys pairvalues);

sub pairgrep(&@) {
    my $code = shift;
    my @result;
    while (@_) {
        local ($a, $b) = splice @_, 0, 2;
        push @result, $a, $b if $code->();
    }
    return @result;
}

sub pairmap(&@) {
    my $code  = shift;
    my @result;
    while (@_) {
        local ($a, $b) = splice @_, 0, 2;
        push @result, $code->();
    }
    return @result;
}

sub pairkeys {
    pairmap { $a } @_;
}

sub pairvalues {
    pairmap { $b } @_;
}

sub test {
    require Test; Test->import;
    plan(tests => 4);
    local $" = ',';
    my @a;

    @a = pairkeys(1..10);
    ok("@a" eq "1,3,5,7,9");
    @a = pairvalues(1..10);
    ok("@a" eq "2,4,6,8,10");
    @a = pairgrep { $a > 5 && $b < 10 } 1..10;
    ok("@a" eq "7,8");
    @a = pairmap { $a * $b } 1..10;
    ok("@a" eq "2,12,30,56,90");
}

test() unless caller();