- rank | rankn = Arbitrary
- | rank2 = Rank 2
- | otherwise
- = case ctxt of -- Haskell 98
- GenPatCtxt -> Rank 0
- LamPatSigCtxt -> Rank 0
- BindPatSigCtxt -> Rank 0
- DefaultDeclCtxt-> Rank 0
- ResSigCtxt -> Rank 0
- TySynCtxt _ -> Rank 0
- ExprSigCtxt -> Rank 1
- FunSigCtxt _ -> Rank 1
- ConArgCtxt _ -> if polycomp
- then Rank 2
+ gen_rank n | rankn = ArbitraryRank
+ | rank2 = Rank 2
+ | otherwise = Rank n
+ rank
+ = case ctxt of
+ DefaultDeclCtxt-> MustBeMonoType
+ ResSigCtxt -> MustBeMonoType
+ LamPatSigCtxt -> gen_rank 0
+ BindPatSigCtxt -> gen_rank 0
+ TySynCtxt _ -> gen_rank 0
+ GenPatCtxt -> gen_rank 1
+ -- This one is a bit of a hack
+ -- See the forall-wrapping in TcClassDcl.mkGenericInstance
+
+ ExprSigCtxt -> gen_rank 1
+ FunSigCtxt _ -> gen_rank 1
+ ConArgCtxt _ | polycomp -> gen_rank 2