Am Freitag, 8. Februar 2008 22:14 schrieb Ben Franksen: > If it's a bug then it is probably in 6.6.1 too, it just gets hidden by the > fact that in 6.6.1 the -fglasgow-exts extensions cannot be activated > separately. If you enable one of them, you get them all. > Thanks for the info, didn't know that.
The problem was the error message, which didn't mention that each type variable may appear only once in an instance head, which I had temporarily forgotten. Then the message Leandro.hs:32:0: Illegal instance declaration for `Container (Abb a b) a b' (All instance types must be of the form (T a1 ... an) where a1 ... an are distinct type *variables* Use -XFlexibleInstances if you want to disable this.) In the instance declaration for `Container (Abb a b) a b' looks rather confusing :) > Cheers > Ben > Cheers, Daniel _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe