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Parser Combinators Beat Regexes

(entropicthoughts.com)
120 points mooreds | 2 comments | 09 Apr 25 21:53 UTC | HN request time: 0.554s | source
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arn3n ◴[10 Apr 25 00:34 UTC] No.43639465[source]▶
“In other languages, it would be considered overkill to write a full parser when a simple regex can do the same thing. In Haskell, writing a parser is no big deal. We just do it and move on with our lives.”

I see a long code file filled with comments and long paragraph-level explanations. I think I’d rather just learn and use regex.

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layer8 ◴[10 Apr 25 02:07 UTC] No.43639965[source]▶
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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1. zokier ◴[10 Apr 25 11:29 UTC] No.43642797[source]▶
> 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...

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2. qrobit ◴[10 Apr 25 12:43 UTC] No.43643224[source]▶
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...>