Yes, you're the last to learn about it; we were all wondering when you would figure it out. ;-) It's definitely "folklore", I can't remember where I first learned about it. I agree with Tom that it's surprising (but nice) that it works even with data types that were not declared using record syntax. I also always find it surprising that record update or matching binds more tightly than function application, so that no parentheses are needed. Sometimes I feel like it would actually look nicer to write f (A1 {}) = ... but then hlint yells at me. (Yes, I'm aware I can turn off individual hlint warnings. =) -Brent On Thu, Nov 30, 2023 at 7:47 AM Noon van der Silk <noonsilk@gmail.com> wrote:
Sometimes I have a type like:
data A = A1 Int | A2 Int Int
Then if I want to do pattern matching and ignore the parameters I do:
f (A1 _) = .. f (A2 _ _) = ...
But that's annoying; I need to remember how many parameters each one has!
Yesterday I learned I can just do this:
f A1 {} = ... f A2 {} = ...
And GHC is happy.
Is this expected? Am I the last to learn about this trick?
-- Noon van der Silk, ن
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