30 Nov
2023
30 Nov
'23
9:06 a.m.
It was unexpected to me because A1 and A2 were not defined as record constructors. (Since I discovered it I now use it regularly; it's very nice.) On Thu, Nov 30, 2023 at 02:58:43PM +0100, David Kraeutmann wrote:
Yes. You're just using record pattern match with no records. Why would it be unexpected?
On 30.11.2023 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?