Hi, Am Montag, dem 16.05.2022 um 19:09 +0000 schrieb Richard Eisenberg:
Hi all,
On a project I'm working on, I wish to declare something like
data Rec = MkRec { field :: forall a. SomeConstraint a => ... }
where the ... contains no mention of `a`.
Even with https://github.com/ghc-proposals/ghc-proposals/pull/448, I think there is no way to avoid the ambiguity when setting `field`. Is that correct? If so, what shall we do about it? The natural answer is somehow to write ... MkRec { field @a = ... } ... but that would break significant new syntactic ground. (Maybe it's good new syntactic ground, but it would still be very new.)
I’m probably revealing ignorance of #448 this way, but why would MkRec { field = \@a -> ...} not work with -XTypeAbstractions Cheers, Joachim -- Joachim Breitner mail@joachim-breitner.de http://www.joachim-breitner.de/