I suppose having a good description of what I'd like to do might help: I'd like to be able to make an N-Tuple an instance of a type class.
class Foo a where .... instance Foo (,) where .... instance Foo (,,) where .... The different kindedness of (,) and (,,) prevent this from working. /jve On Mon, Mar 30, 2009 at 2:00 PM, Martijn van Steenbergen < mart...@van.steenbergen.nl> wrote: > John Van Enk wrote: > >> > Haskell not having 'polymorphic kinds'. >> Is there a good description of why Haskell doesn't have polymorphic >> kinds? >> > > IANA expert but polymorphic kinds belong to a set of reasonably new > influences (e.g. from dependently typed programming languages and generic > programming) and they haven't been 1) polished enough to be a widely > accepted standard or 2) simply haven't been implemented yet (low priority, > etc). > > Besides that, I sometimes see polymorphic kinds in GHC error messages, so I > suspect that at least parts of GHC already support them. > > Martijn. > > -- /jve
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