SPUG: Grep syntax

[Yitzchak Scott-Thoennes]

On Fri, June 15, 2007 11:32 pm, Bill Campbell wrote:
> My original request was (a) to try to figure out why somebody
> would use grep in a manner that wasn't about pattern recognition, but used
> for looping, and (b) I think I said that map would be a more logical
> choice for that.

grep, used in the normal way, is about list selection.  Pattern
recognition is one common way of doing that selection, but
seeing grep used in other ways shouldn't be a surprise.
For instance, one way of finding the keys two hashes have
in common is:

  @common_keys = grep exists $hash2{$_}, keys %hash1;