[Haskell] question about a failure to generalize

Norman Ramsey wrote: : | This code fails to compile because the compiler is willing to | use 'fold' at only one type (CmmExpr as it happens) : When it failed to compile, was fold = foldRegsUsed a top-level declaration in the module, rather than local to foldRegsUsed? If so, try working around the monomorphism restriction by changing from a pattern binding to a function binding. fold f = foldRegsUsed f Regards, Tom