`greb` : Grep Using PARSE?

There was a Trello card with a remark from @johnk about an idea from Pekr:

Not sure how this would work, but it is an interesting excercise to think about. Something that bridges between unix and rebol syntax like:

ls | greb 'some alpha ".reb"'

(assuming a few more built in rules/charsets)

May need a collect/keep kind of wrapper to retrieve data cleanly.

This would be a very small subset of what @BlackATTR's QUERY could do...but it seems like it wouldn't hurt if we went ahead and made this program as a test and put it in the ren-c-stdio repository.

I've already made things like TAC (backwards unix CAT), where the goal is to see how essential and correct we can make things:

I like the idea of making GREB similarly essential, and part of the samples. Worth doing.

(Note that grep was itself originally framed as a one-line awk program.)

I'll also throw in a little ping that it would be nice to have a simple web app that exposed PARSE functionality with some highlighting, like http://regexpal.com/. Seems sometimes we get such big ideas in our head we forget to do the small ones (!)