| > arbitrarySeq :: Sequence a -> Gen RepSeqVal | > arbitrarySeq Nil = | > return (RepSeqVal Nil Empty) | > arbitrarySeq (Cons (CTMandatory (NamedType n i t)) ts) = | > do u <- arbitraryType t | > us <- arbitrarySeq ts | > case u of | > RepTypeVal a v -> | > case us of | > RepSeqVal bs vs -> | > return (RepSeqVal (Cons (CTMandatory (NamedType n i a)) bs) (v:*:vs)) | | | > QuickTest.lhs:240:13: | > GADT pattern match in non-rigid context for `Nil' | > Solution: add a type signature | > In the pattern: Nil | > In the definition of `arbitrarySeq': | > arbitrarySeq Nil = return (RepSeqVal Nil Empty) That looks odd to me. But it's hard to help without having the code. If you send it I'll try to help. | > Did you try giving a type signature to the (entire) case expression, | > as I suggested? That should do it. | > | | I'm not sure what this means or how to do it. Can you give an example or | is it buried in some earlier email? I will go and have another look. I mean replace (case blah of { ... }) by (case blah of { ... }) :: type-sig That is, attach a type signature to the case expression itself. Does that help at least explain what the sentence means? If so would you like to clarify the wiki advice? Thanks Simon