+
+ -- Figure out the appropriate kind for the pattern,
+ -- and generate a suitable type variable
+ (case is_rec of
+ Recursive -> newTyVarTy boxedTypeKind -- Recursive, so no unboxed types
+ NonRecursive -> newTyVarTy_OpenKind -- Non-recursive, so we permit unboxed types
+ ) `thenNF_Tc` \ pat_ty ->
+
+ -- Now typecheck the pattern
+ -- We don't support binding fresh type variables in the
+ -- pattern of a pattern binding. For example, this is illegal:
+ -- (x::a, y::b) = e
+ -- whereas this is ok
+ -- (x::Int, y::Bool) = e
+ --
+ -- We don't check explicitly for this problem. Instead, we simply
+ -- type check the pattern with tcPat. If the pattern mentions any
+ -- fresh tyvars we simply get an out-of-scope type variable error