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    <p>While the accepted answer implements a <code>map</code>-like function, it does NOT do it in the way perl would. An important part of <code>for</code>, <code>foreach</code>, <code>map</code>, and <code>grep</code> is that the <code>$_</code> they provide to you is always an alias to the values in the argument list. This means that calling something like <code>s/a/b/</code> in any of those constructs will modify the elements they were called with. This allows you to write things like:</p> <pre><code>my ($x, $y) = qw(foo bar); $_ .= '!' for $x, $y; say "$x $y"; # foo! bar! map {s/$/!!!/} $x, $y; say "$x $y"; # foo!!!! bar!!!! </code></pre> <p>Since in your question, you have asked for <code>Map</code> to use array references rather than arrays, here is a version that works on array refs that is as close to the builtin <code>map</code> as you can get in pure Perl.</p> <pre><code>use 5.010; use warnings; use strict; sub Map (&amp;\@) { my ($code, $array) = splice @_; my @return; push @return, &amp;$code for @$array; @return } my @sample = qw(1 2 3 4 5); say join ', ' =&gt; Map { $_ * $_ } @sample; # 1, 4, 9, 16, 25 say join ', ' =&gt; map { $_ * $_ } @sample; # 1, 4, 9, 16, 25 </code></pre> <p>In <code>Map</code>, the <code>(&amp;\@)</code> prototype tells perl that the <code>Map</code> bareword will be parsed with different rules than a usual subroutine. The <code>&amp;</code> indicates that the first argument will either be a bare block <code>Map {...} NEXT</code> or it will be a literal code reference <code>Map \&amp;somesub, NEXT</code>. Note the comma between the arguments in the latter version. The <code>\@</code> prototype indicates that the next argument will start with <code>@</code> and will be passed in as an array reference.</p> <p>Finally, the <code>splice @_</code> line empties <code>@_</code> rather than just copying the values out. This is so that the <code>&amp;$code</code> line will see an empty <code>@_</code> rather than the args <code>Map</code> received. The reason for <code>&amp;$code</code> is that it is the fastest way to call a subroutine, and is as close to the multicall calling style that <code>map</code> uses as you can get without using C. This calling style is perfectly suited for this usage, since the argument to the block is in <code>$_</code>, which does not require any stack manipulation.</p> <p>In the code above, I cheat a little bit and let <code>for</code> do the work of localizing <code>$_</code>. This is good for performance, but to see how it works, here is that line rewritten:</p> <pre><code> for my $i (0 .. $#$array) { # for each index local *_ = \$$array[$i]; # install alias into $_ push @return, &amp;$code; } </code></pre>
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