#! /usr/bin/perl

use strict;
use warnings;

map { print "$_->[0] -> $_->[1]\n" } &{
  sub {
    return @_ == 1
      ? undef
      : ( [ splice @_, -2 ], @_ == 1 ? () : &{ $_[0] }(@_) );
    }
  }(
  sub {
    return @_ == 1
      ? undef
      : ( [ splice @_, -2 ], @_ == 1 ? () : &{ $_[0] }(@_) );
  },
  %{ { x => 5, y => 8, z => 42 } }
  );