On Tue, Feb 15, 2011 at 7:02 AM, Noel Welsh <[email protected]> wrote: > So this isn't really ad-hoc, is it? I can't extend the type in another > module (typically done with structure properties in Racket). Anyway, a > union type will do for me, for now.
It's ad-hoc for me, but not for thee. :) We have a story for ad-hoc polymorphism involving `case->', but that's fixed rather than user-extensible. The kind of extensible ad-hoc polymorphism that struct properties provide (and that is provided by typeclasses in Haskell) is not currently supported in Typed Racket -- I expect that figuring out the right type system for struct properties will require new research. > > Cheers, > N. > > On Mon, Feb 14, 2011 at 9:57 PM, Vincent St-Amour <[email protected]> > wrote: >> For the built-in functions that are currently supported by TR, the >> ad-hoc polymorphism should work. If you want to write your own ad-hoc >> polymorphic functions, you can give them types constructed with the >> case-lambda type constructor (which is not the same thing as Racket's >> case-lambda macro): >> http://docs.racket-lang.org/ts-reference/index.html?q=case-lambda#%28form._%28%28lib._typed/racket/base..rkt%29._case-lambda%29%29 >> >> In git, you can also use case-> as a synonym for case-lambda. >> >>> In particular, I'd >>> like to use the dict library. >> >> The dict library is not currently supported. The main problem is that >> I'm not aware of a way to express the fact that a (Vectorof X) is a >> (Dictof Integer X) in TR's type system, which currently makes dict >> operations untypeable. We could give them types that exclude vectors, >> though. >> >> Would that be an acceptable solution for you? >> >> Vincent >> > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users > -- sam th [email protected] _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
