I absolutely love to use Haskell when teaching (and I have several years of experience doing it). And I absolutely dislike it when I have to jump through hoops to declare types in the most correct way, and in the most natural places. This is hard to sell to the students. - Examples: 1. for explicit declaration of type variables, as in reverse :: forall (a :: *) . [a] -> [a] I have to switch on RankNTypes and/or KindSignatures (ghc suggests). C'mon, this has nothing to do with ranks per se. It's a type of a very simple function! IMHO even Java/C# do this better (with slightly strange syntax, but at least you get to declare the type variable). 2. for declaring types of local variables, as in \ (xs :: [Bool]) -> ... I have to enable PatternSignatures (actually ghc suggests ScopedTypeVariables but again there is no type variable in sight) I need to do this often, to disambiguate properties for Smallcheck. All of this just because it seemed, at some time, a clever idea to allow the programmer to omit quantifiers? (I know, mathematicians do this all over the place, but it is never helpful, and especially not when teaching.) I think that (1) implies (2): there could be no ambiguity about scopes (of typevars in patterns) if each typevar had to be introduced by explicit quantification. Then (in a pattern signature) a use could be distinguished from a declaration. Yes, the above is a rant. I can achieve what I want with some ghc options, and perhaps my point is that these should be on by default - or have better names, because presently, they are unintelligible to the (beginner) student.