To clarify, are you suggesting guidelines for GHC **and** base-library? I'm puzzled about ownership of base. Who have a final word about it? ghc-devs, librar...@haskell.org, CLC, chessai alone, whoever is first?
- Oleg On 21.5.2021 23.21, Richard Eisenberg wrote: > I agree with Chris here. > > Let me expand upon my counter-proposal: > > * A datatype declaration gets a standalone kind signature whenever at > least one of its type arguments has a kind other than Type. > * A class declaration gets a standalone kind signature whenever at > least one of its type arguments has a kind other than Type.(*) > * A closed type family always gets a standalone kind signature. > * A type synonym gets a standalone kind signature whenever either at > least one of its arguments has a kind other than Type or its result > has a kind other than Type. > > (*) The class rule has an exception: if a class has a superclass > constraint using Monad, Functor, Applicative, Foldable, or Traversable > (or some other class whose name textually includes one of those names, > such as MonadIO), we understand that the constrained variable must > have kind Type -> Type. If that type variable is the only one without > kind Type -> Type, then the standalone kind signature is optional. > > In cases other than those covered above, the standalone kind signature > is optional, at the discretion of the programmer. > > This suggests that Dict gets a signature, Eq does not, Fix does, and > Either does not. > > Richard > >> On May 21, 2021, at 12:37 PM, Chris Smith <cdsm...@gmail.com >> <mailto:cdsm...@gmail.com>> wrote: >> >> On Fri, May 21, 2021 at 2:11 AM Baldur Blöndal <baldur...@gmail.com >> <mailto:baldur...@gmail.com>> wrote: >> >> > encouraging the use of a standalone signature for type >> declarations where at least one parameter of the datatype does >> not have kind Type. >> >> So Dict, Eq both get a sig but Fix and Either do not? >> >> type Dict :: Constraint -> Type >> type Eq :: Type -> Constraint >> type Fix :: (Type -> Type) -> Type >> >> >> That's not how I understand Richard's criteria. Dict and Fix have >> non-Type parameters (Dict has a Constraint parameter, and Fix has a >> (Type -> Type) parameter. On the other hand, Eq and Either have only >> Types as parameters. This seems to match my intuition about when a >> kind signature might be helpful, as well as yours as far as I can >> tell from what you wrote. >> >> That's not to say I am advocating any kind of rule. As I'm not >> really involved in GHC development, I refrain from having any >> opinion. I just think you may have misread Richard's suggestion. > > > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
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