Hello, playing with GADTs I ran into a problem with rigid type variables which is ilustrated by the following example. I think it should be pretty clear what I'am trying to express... Any suggestions? ---- snip ---- {-# LANGUAGE GADTs #-} data Foo where Foo :: (Eq t) => t -> Foo instance Eq Foo where (Foo a) == (Foo b) = a == b {- Scratch.hs:7:28: Couldn't match expected type `t' against inferred type `t1' `t' is a rigid type variable bound by the constructor `Foo' at /home/alios/src/lab/Scratch.hs:7:3 `t1' is a rigid type variable bound by the constructor `Foo' at /home/alios/src/lab/Scratch.hs:7:14 In the second argument of `(==)', namely `b' In the expression: a == b In the definition of `==': (Foo a) == (Foo b) = a == b Failed, modules loaded: none. -} ---- snip ---- thnx Markus