A lot of times, golf is about shaving off a few characters here and there. I'm sure these have been pointed out before, but:
For control flow, you want for, map, and punctuation. map and for are largely interchangeable. while is almost never necessary. Don't forget about the C-language-style for(;;), although it's rarely a gain. Postfix your operators; statement-modifier for doesn't require the parens or the braces that make a BLOCK. Replace branching if() statements with ternary or logical operators. Precedence rules will help here; also, remember that in Perl, true is '1' and false is the empty string. If you don't need the short-circuiting, you can use the bitwise flavor of & and |. Know which builtin variables are used and what special effects they have. ($- and $=, I'm looking at you.)

From the snippets you have posted:

$o .= $p >= 0 ? $a[$p] : $_;
could become $o .= $p < 0 ? $_ : $a[$p] and
$r =~ s/[^a-z]//g;
could become $r =~ y/a-z//cd;

In reply to Re: Perl Golf 101 by whio
in thread Perl Golf 101 by chargrill

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