Re: Duplicate instance declarations of a methodless class

Alfonso Acosta:

Did you try to compile with -fallow-overlapping-instances

mm :

Same effect:

ghc -fallow-overlapping-instances --make test5.lhs [1 of 1] Compiling Main ( test5.lhs, test5.o )

test5.lhs:22:1: Duplicate instance declarations: instance [overlap ok] (Succ a b) => GT a b -- Defined at test5.lhs:22:1 instance [overlap ok] (Succ a b, GT b c) => GT a c -- Defined at test5.lhs:23:1

Also see Oleg's post in this thread: http://www.haskell.org/pipermail/haskell-cafe/2007-February/022926.html