#!/usr/bin/perl

use 5.14.0;
use strict;
use warnings;

sub my_splice_like_func
{
    my ($list, $offset, $length) = @_;
    my @copy = @$list;
    return splice @copy, $offset // 0, $length // @copy - $offset;
}

$, = ' ';                               # just keepin' it pretty

my $list = [qw< one two three four >];
say my_splice_like_func($list, 2);      # want "three four"; get "two three four"
say my_splice_like_func($list, 2, -1);  # want "three"; get "three four"