On 22 December 2011 00:10, José Pedro Magalhães <j...@cs.uu.nl> wrote: > Hi Bas, > > On Wed, Dec 21, 2011 at 23:02, Bas van Dijk <v.dijk....@gmail.com> wrote: >> >> On 21 December 2011 19:29, Ian Lynagh <ig...@earth.li> wrote: >> > * There is a new feature constraint kinds (-XConstraintKinds): >> > >> > http://www.haskell.org/ghc/dist/stable/docs/html/users_guide/constraint-kind.html >> >> I'm trying to run the ConstraintKinds example from the documentation: >> >> {-# LANGUAGE ConstraintKinds, TypeFamilies #-} >> type family Typ a b :: Constraint >> type instance Typ Int b = Show b >> type instance Typ Bool b = Num b >> >> But GHC complains: >> Not in scope: type constructor or class `Constraint' >> >> Do I have to import some GHC module for this? > > > Yes: GHC.Prim. > > (Which reminds me, Simon, we had agreed to re-export Constraint from > GHC.Exts, but it wasn't clear to me how to do this, since Constraint is a > kind, not a type, so it can't just go on the export list of the module...) > > > Cheers, > Pedro > >> >> >> Cheers, >> >> Bas >> >> >> _______________________________________________ >> Glasgow-haskell-users mailing list >> Glasgow-haskell-users@haskell.org >> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > >
Thanks Pedro, that works. I already read through the docs of GHC.Prim but could not find it: http://www.haskell.org/ghc/dist/stable/docs/html/libraries/ghc-prim-0.2.0.0/GHC-Prim.html I guess haddock is not smart enough to understand kinds yet... _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users