This comment is not nearly as useful as one that gives examples about your reasoning (or at least a link to such.)

Sorry, I thought people would be intrigued and google it.

http://betterthangrep.com/

A quote:

"ack is a tool like grep, aimed at programmers with large trees of heterogeneous source code.

ack is written purely in Perl, and takes advantage of the power of Perl's regular expressions."

Ack could have been done just as well with a 10 line shell wrapper around grep. It would have been much faster, on top of being simpler.

Put thine code where thy mouth is.