Day 1: Secret Entrance

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FAQ

  • Camille@lemmy.ml
    2·
    5 days ago

    Why are you preferring lambda-case over plain old pattern matching as in the following snippet? I didn’t know this language feature existed and I am now curious :)

    applyRotation :: Int -> Either Int Int -> Int
applyRotation x (Left y) = (x - y) `mod` 100
applyRotation x (Right y) = (x + y) `mod` 100
    • VegOwOtenks@lemmy.worldEnglish
      1·
      5 days ago

      Thank you for the excellent question. This made me reflect on my coding style and why I actually chose this. Maybe you have noticed, my usage of LambdaCase is inconsistent: I didn’t use it in the definition of foldRotation. Which happened with some refactorings (You couldn’t know that, I didn’t tell anywhere), but still.

      After going through some ‘old’ code I found that I didn’t start using it until early this year. (For context: I started doing Haskell in September 2024) But that may just coincide with me installing HLS.

      Anyway, back to the topic: I actually think it’s very elegant because it saves re-typing the function name and/or other parameters. It also easily allows me to add further arguments to the function (but only before the last one). In my mind, this is where LambdaCase shines.

      Sometimes I end up refactoring functions because it’s very hard to match on multiple arguments using LambdaCase. I also try to avoid adding arguments in the back, which might bite me later and limits flexibility a lot.

      Moaaar Backstory

      I picked it up in some forum discussion I read where somebody argued that using explicit matches litters the Codebase with re-definitions of the same functions. It makes grep-ing the source hard. I was easily influenced by this and adopted it.

      I think this is not the way I like to go about it. I would rather use Hoogle, Haddock or HLS to search in my source.