(* the difference by "(type a) ..." and "type a . ..." is that the latter allows polymorphic recursion (just as "'a . ..."), so this example fails with just (type a) *)
So here's a question which has been nagging me for a while: is there any occasion where one may prefer to use the `(type a)` or the `'a.` forms over the `type a.` (apart for syntactical reasons)? If there is I'd be really interested in seeing an example, for I can't come up with one (especially for `(type a)`). If there aren't, what are the obstacles to turn the `(type a)` syntax into a synonymous to the `type a.` syntax? (I'm guessing that the `'a.` variant would be significantly harder).