On 26 August 2011 09:22, Simon Peyton-Jones <simo...@microsoft.com> wrote: > The underlying issue is that before type checking GHC (obviously) doesn't > know the types of things, while afterwards it does. The whole HsSyn tree is > parameterised over the types of identifiers: > > Parsed: HsExpr RdrNames > Renamed: HsExpr Name > Typechecked: HsExpr Id > > One alternative would be to parameterise the tree over the type of > type-decorations, so instead of 'PostTcType' you'd have 'ty' (a variable) > instead. So we'd have > > Renamed: HsExpr Name () > Typechecked: HsExpr Id Type > > To me this seems like a bit of a sledgehammer to crack a nut; and I think > there are a couple of other similar things (like SyntaxExpr). But it might > be possible.
Type functions? data HsExpr name = ... | HasTypeArgument (TypeInfo name) type family TypeInfo name :: * type instance TypeInfo RdrName = () type instance TypeInfo Name = Type This basically lets you get away with just a single type index to HsExpr and friends. Max _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
