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Comment by layer8 | Hacker News Reader

Whenever I write a regex, I end up with a comments roughly ten times longer than the regex. That being said, regular expressions are often the right tool for the job (i.e. parsing a regular language, as opposed to a context-free language or whatever), just the syntax becomes unreadable rather quickly. I’m sure you could build a nicer regular-expression syntax in Haskell.

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I love the verbose flag[0] to regex, so I can write comments inline.

[0] https://docs.python.org/3/library/re.html#re.VERBOSE

Yes. Regex tend to become rather fast write only. One solution is commenting, but is still complex. What I like to do now (in C) is define parts of it. Just a crude example to get the idea:

   // STRing: matches anything inside quotes (single or double)
   #define STR "[\"'](.*)[\"']"
   // NUMber: matches decimal or hexadecimal numbers
   #define NUM "([[:digit:]]x?[[:xdigit:]]*)"
   
   regcomp(&reg_exp, STR NUM , REG_EXTENDED | REG_ICASE);

So at the end I compose the RE with the various parts, which are documented separately.

> just the syntax becomes unreadable rather quickly. I’m sure you could build a nicer regular-expression syntax in Haskell.

Of course regular expressions are really more of a category of expressions, and the traditional kleene star notation is only one of many options; regular expressions do not somehow inherently need to use that specific syntax.

Pomsky and VerbalExpressions are just some examples of alternative syntaxes for regex. Apparently there is even a port of VerbalExpressions for Haskell:

https://github.com/VerbalExpressions/HaskellVerbalExpression...

I looked at the VerbalExpressionJS[1] example and it looks like combining parsers to me. If you need to make regex more verbose, better use parser combinator library when available. RegEx benefits compared to parser combinators other than compactness aren't obvious to me.

[1]: <https://github.com/VerbalExpressions/JSVerbalExpressions/tre...>

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