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  • Hacker News
  • It's a pity that the Perl6 saga killed the new regex ideas - I wish the raku regexes were adopted elsewhere (like the Perl5 regexes were): https://docs.raku.org/language/regexes
    by zby
  • Before the AI craze, I'd gotten quite good at writing regexes. Regexr was quite useful for decoding and composing them. I feel like they're going to become a lost art.
    by isqueiros
  • Just like jq there will be some lad along to tell us that "I don't like the syntax and find it confusing" not realising that's the exact superpower it presents is it's terseness is a key property to it's adoption. jq and regex really are sort of handy one liners that you invoke in other scripts and you explain what they do in your script with a comment.
    by s_dev
  • It might just be a me problem, but I've always been wary of regexes. They're not too bad to write, but reading them back and understanding what's actually going on can get a bit hairy. Plus, all of the subtle differences between regex libraries seems like a bit of a footgun.

    Obviously they have their place, but I know a lot of the older guys seemed to love them way more than the young.

    by AussieWog93
  • Some people, when confronted with a problem, think "I know, I'll get my agent to solve it with regular expressions."

    Now they have three problems.

    by cadamsdotcom
  • "Doom Using Regular Expressions" https://news.ycombinator.com/item?id=49094081
    by HelloUsername
  • Something that seems obvious but not always implied by people's comments is that people are rarely trying to match an entire document with a regular expression so it doesn't really matter that "HTML is not a regular language".

    If I am trying to e.g. count div tags with a regex like "<div" or whatever, then clearly this would work in 99.9% of cases and probably achieve what the poster is looking for.

    As soon as you also add character classes to ignore various parts of the document that you are not interested in like "<div[^>]*>" or whatever it is, then it is eminently useful even if the bit we are ignoring is not fully regular.

    One lovely thing about regex is how fast it is. I was asked to parse a massive CAN Bus log file for how many times some event had logged. This was the early 2000s and the file was 6GB, which was pretty big. I tried .Net's string.StartsWith or something and that took ages to run through the file. I did the same thing with a regex and it finished in like 5 seconds (HDD, not SSD!). I don't know how the magic works but it is very impressive.

    by lbriner
  • This article misleads you by conflating regular expressions with specific implementations like PCRE, which also does non-regex string matches. Annoyingly, the article does a good job of explaining what a regex is and what the limitations of regex are relative to PCRE, so the author should understand that what they are talking about when they talk about NP-complete string matching is not regex, but PCRE-specific features.

    The distinction matters because regex absolutely can't match HTML, and because regex, unlike PCRE expressions, have guaranteed O(1) space and O(n) time complexity when matching a string of length n. When you use PCRE features for string matching, that may degrade to exponential time which makes it useless. For example, you can do denial of service PCRE attacks, but not denial of service regex attacks (unless you can query with some megabyte-large regex).

    by jakobnissen

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