Not all splices are the same

[Matthew Pickering]

Seems related to https://gitlab.haskell.org/ghc/ghc/-/issues/18211

There is also a small section in my thesis (4.1.2) which explains why
changing the implementation of typed quotations would allow this
program to be accepted.

Matt

On Sun, Jan 23, 2022 at 7:08 PM David Feuer <david.feuer at gmail.com> wrote:
>
> I've been a bit upset by the challenges Template Haskell poses for type inference. For example,
>
> (3 :: Int) == $$(...)
>
> may typecheck when
>
> $$(...) == (3 :: Int)
>
> does not. I don't imagine this problem can be solved in general, but I'm rather curious whether it might be possible to solve for "pure" splices, with types that look like
>
> forall m. Quote m => Code m a
>
> Would it be possible to get full bidirectional inference for these if they were somehow marked specially by the user? For instance, if I wrote
>
> $$$e
>
> that could mean e should be interpreted as having some type
>
> PCode a
>
> where
>
> newtype PCode a = PCode (forall m. Quote m => a)
> _______________________________________________
> ghc-devs mailing list
> ghc-devs at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs