Using grep in boolean context is a common idiom for checking if any elements in a list match a condition. This works because boolean context is a subset of scalar context, and grep returns the number of matches in scalar context. A non-zero number of matches means a match.

But consider the case of a long array where the first element is a match. Boolean grep still checks all of the rest of the elements needlessly. Instead, a better solution is to use the any function from the List::MoreUtils manpage, which short-circuits after the first successful match to save time.


The algorithm for detecting boolean context takes a LOT of shortcuts. There are lots of known false negatives. But, I was conservative in writing this, so I hope there are no false positives.


Chris Dolan <cdolan@cpan.org>


Initial development of this policy was supported by a grant from the Perl Foundation.


Copyright (c) 2007 Chris Dolan. Many rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license can be found in the LICENSE file included with this module.