The use of map or grep in Perl

I've been writing perl code full-time for a couple months now(bioinformatics), and am always trying to improve my skills. Just today, it dawned on me that I never use map or grep. Looking back through my code I realize these tools could save me a couple lines here or there, but only at the expense of the flexibility of a foreach loop. My question is as follows:

Are there any circumstances you have run across where using map 开发者_运维问答or grep has brought significant advantage over a foreach/for loop, beyond saving a line or two of code?

Thanks for your time!

The Schwartzian Transform would be an example:

@sorted = map  { $_->[0] }
          sort { $a->[1] cmp $b->[1] }
          map  { [$_, foo($_)] }
          @unsorted;

You could do that with a pile of foreach loops but you'd have to pick them apart to figure out what was going on; once you've seen the Schwartzian Transform you recognize the idiom immediately.

In general I think map and grep are good in that they allow you to clearly and compactly represent your intent without layers of syntax. If you see a map then you know that some sort of simple data structure transformation is going on; if you see a grep then you know that some filtering/selection is going on. You could do it all with foreach but the intent of your code isn't as clear as it would be with map or grep; you could even do it all with if and goto if you wanted to but then your intent would be buried under even more syntax and state tracking.

I'm constantly using map and grep. And apply, first, any, and many others from List::MoreUtils. I find that, in general, they explain what the code is doing as opposed to how the code is doing it.

In general, I find that when my code reads the same as the spec, it's more likely to be correct as well as more likely to handle corner/edge cases. Perl allows me to do this much better than any language I've used in the past, and I take advantage of it.

For example, if my spec says that I will do foo() if $blah is in some list, my code reads exactly that way:

foo() if any { $_ eq $blah } some_list();

Same idea for the rest of these tools. The code and the spec look eerily similar, and that's one of the great things about Perl.