Re: [Haskell-cafe] Strange quirk with {} syntax?

I’ve known it for a while and use it now and then. There are quite a few packages on Hackage that use it: https://hackage-search.serokell.io/?q=%5BA-Z%5D%5Ba-zA-Z0-9%27_%5D*%5Cs%2B%5...

On 30 Nov 2023, at 14:46, Noon van der Silk 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

http://silky.github.io/

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