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Comment by idbehold | Hacker News Reader

> NOTE, delimiters must be included

Your regex is actually /a/ which does not match the string "/a/".

I would say that adding slashes is quite arbitrary constraint, and it is really language specific syntax that is limited to minority of languages (I believe it was introduced in Perl). If you do regexp in Java, Python, C you don't use slashes.

Edit: looks like slashes weren't even used in the example.

It's a pretty boring question if you don't make that requirement, though. The whole exercise is arbitrary, so it doesn't bother me.

Okay, I'll quote some more from the question:

> […] for the sake of the challenge, let the expression be delimited (starting symbol, expression, ending symbol ex: /fancypantpattern/ or @[^2048]@), if you want to argue quotes as your delimiter, so be it. I think given the apparent difficulty of this problem it won't make much of a difference.

Perl's use of this syntax had ancestors in awk, sed, ed, and qed - originally just for string replacements in qed until Ken Thompson wrote a version that did regexps too. It dates back to 1967. https://www.bell-labs.com/usr/dmr/www/qed.html

Deutsch&Lampson's original paper on qed showing s/// used for string substitution prior to it gaining regexps is here: http://research.microsoft.com/en-us/um/people/blampson/04-On...

Incidentally the name 'grep' originated here, 'G/RE/P' was a qed command to do a Global Regular Expression match and Print the matches.

Ahh. Thank you.

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