On Sat, Sep 22, 2012 at 12:20 PM, Eli Barzilay <e...@barzilay.org> wrote: > >> What I'm suggesting is that some unions (e.g. `Natural') be opaque >> even to the introspection tool. Since there's no way to get >> something to typecheck as `Positive-Integer-Not-Fixnum' (the >> typechecker will never give that type to anything, it's just a trick >> to get more precise intersections) showing it in `:type''s output is >> confusing. > > That's mainly something that goes in the PR, since with my thing there > is some point in showing the hidden types. But the similarity is how > the above translates to my case: I want a way to treat my user-defined > `SOMETHING' as opaque, and I want to hook into the typechecker a > restriction that TR would never give the hidden `This' type to > anything. (And I think that I have that latter part, for >=2 > variants.)
But you need the type `This` to be used in typechecking the expansion of `cases`, so that `This-field` selection works. -- sam th sa...@ccs.neu.edu _________________________ Racket Developers list: http://lists.racket-lang.org/dev