#!/usr/bin/env perl
use 5.010;
use strict;
use warnings;

sub foo(&@) {
    my $coderef = shift;
    my @ret;

    push @ret, $coderef->() for @_;

    return @ret;
}

my @a = ( "1", "2", "3", "4", );
my @b = foo( sub { $_ ** 2 }, @a);