#! /usr/bin/perl -w

use strict;
use Test;

sub foldl {
    my ($fn, $base, @list) = @_;

    foreach my $foo (@list) { 
        $base = &$fn($base, $foo);
    }

    return $base;
}

sub foldl1 {
    my ($fn, @list) = @_;

    my $base = shift @list;
    return &foldl($fn, $base, @list); 
}

sub foldr {
    my ($fn, $base, @list) = @_;

    foreach my $foo (reverse @list) {
        $base = &$fn($foo, $base); 
    }

    return $base;
}

sub foldr1 {
    my ($fn, @list) = @_;

    my $base = pop @list;
    return &foldr($fn, $base, @list); 
}

BEGIN { plan tests=>4 }

ok(&foldl (sub {$_[0] - $_[1]}, 11, (1..10)), -44);
ok(&foldl1(sub {$_[0] - $_[1]},     (1..10)), -53);
ok(&foldr (sub {$_[0] - $_[1]}, 11, (1..10)), 6);
ok(&foldr1(sub {$_[0] - $_[1]},     (1..10)), -5);