Hi, I think I don't quite understand the question. The code you propose seems wrong to me for a different reason: The type constructor (->) for function values has Kind: * -> * -> * In fact, GHC will print this error when compiling the snippet with the corresponding extensions. Promoting a data type is done differently. Can you elaborate on what exactly it is you are proposing? Sincerely Kai Prott On 03.05.21 14:04, coot@coot.me wrote:
Hello,
Currently with `DataKind` extension, Haskell allows to promote terms / types to types / kinds. Currently, one cannot write:
``` data K a where K0 :: forall (x :: a). x -> K a ```
Because `K0` is both a term and a type constructor, and as a term and one cannot represent `x` of kind `a`. Is there a proposal or an issue to allow such declaration and error at use sites of `K0` as a term, rather than at declaration site?
Best regards, Marcin Szamotulski
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