Close - it compiles now! I made a minor change, going to Typeable1 instead of Typeable:
instance (Typeable1 f, Typeable1 g) => Typeable1 (f :+: g) where typeOf1 l@(Inl x) = mkTyConApp (mkTyCon "Planning.Wouter.:+:") [typeOf1 x, typeOf1 y] where (Inr y) = undefined `asTypeOf` l typeOf1 r@(Inr y) = mkTyConApp (mkTyCon "Planning.Wouter.:+:") [typeOf1 x, typeOf1 y] where (Inl x) = undefined `asTypeOf` r Except this gives me a runtime error: *WouterTest> getName testNamed "*** Exception: Prelude.undefined The only thing I can think of is to have a class that gives default values to type - ick! -Ron Alford On Thu, Jul 10, 2008 at 4:16 PM, Antoine Latter <[EMAIL PROTECTED]> wrote: > On Thu, Jul 10, 2008 at 2:15 PM, Ron Alford <[EMAIL PROTECTED]> wrote: >> I'm making progress, but how would I make the following a Typeable instance: >> data (f :+: g) e = Inl (f e) | Inr (g e) deriving Eq >> >> Here is what I'm using for Expr: >> data Expr f = In (f (Expr f)) >> instance Typeable1 f => Typeable (Expr f) where >> typeOf (In x) = mkTyConApp (mkTyCon "Data.Trie.General.ListGT") [typeOf1 >> x] >> >> I don't think I can use this for ':+:', because the typeOf instance >> only has access to a member of one type at a time. >> This may be similar to a definition of Typeable2 for Either, but I >> can't find an example to follow for that. >> > > Maybe something like: > > instance (Typeable1 f, Typeable1 g) => Typeable (f :+: g) where > typeOf in@(InL f) = (some function of 'f' and 'g') > where InR g = undefined `asTypeOf` in > > typeOf in@(InR g) = (some function of 'f' and 'g') > where InL f = undefined `asTypeOf` in > > would work? > > -Antoine >
WouterTest.hs
Description: Binary data
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe