Oh, of course. A polymorphic type just is a type constructor with arrow kind. Sorry. -J
On Tue, Jun 17, 2014 at 11:06 PM, Alexander D. Knauth <alexan...@knauth.org> wrote: > But apply-able types are represented as polymorphic types, with All being a > kind of lamba-ish thing (I think), > so this works: > #lang typed/racket > (define-type Type-Identity (All (t) t)) > (define-type MyZero (Type-Identity Zero)) > (ann 0 MyZero) > > And the documentation for define-type says that > (define-type (name v …) t) > is equivalent to > (define-type name (All (v …) t)) > > Given that, and the fact that (All (a … a ooo) t) is allowed, and that (List > t … trest … bound) is allowed, > (All (a …) (List a … a)) seems like should work, but it doesn’t. > > On Jun 17, 2014, at 10:51 PM, Jon Zeppieri <zeppi...@gmail.com> wrote: > >> Well, I think that's because MyList had a different kind than List. List is >> a type constructor but not a type. MyList, on the other hand, is a >> (polymorphic) type, and it can't be applied; rather, its type variables need >> to be instantiated. Though, given its definition, I don't see how you could >> instantiate all of them. >> >>> On Jun 17, 2014, at 8:48 PM, "Alexander D. Knauth" <alexan...@knauth.org> >>> wrote: >>> >>> Could you represent it with something like (All (a …) (List a … a))? >>> >>> From reading the documentation it seems like it should work, but >>> When I tried it, I got this: >>> >>> #lang typed/racket >>> >>> (define-type MyList (All (a ...) (List a ... a))) >>> >>> (ann '(1 2 3) (MyList 1 2 3)) >>> >>> . Type Checker: Type MyList cannot be applied, arguments were: (One 2 3) >>> in: (MyList 1 2 3) >>> >>>> On Jun 17, 2014, at 8:33 PM, J. Ian Johnson <i...@ccs.neu.edu> wrote: >>>> >>>> I imagine it's because there are no variable-arity type constructors in >>>> TR, and (List A ...) is fancy syntax for (Pairof A (Pairof ... '()) ...) >>>> if that notation makes any sense. >>>> -Ian >>>> ----- Original Message ----- >>>> From: "Spencer Florence" <spen...@florence.io> >>>> To: "racket" <users@racket-lang.org> >>>> Sent: Tuesday, June 17, 2014 5:32:55 PM GMT -05:00 US/Canada Eastern >>>> Subject: [racket] define-type on List and Listof >>>> >>>> >>>> >>>> Hi all, >>>> >>>> I'm trying to rename some types in typed/racket but something odd is >>>> happening: >>>> >>>> >>>> (define-type A Listof) >>>> >>>> works but: >>>> >>>> >>>> (define-type B List) >>>> >>>> errors with "Type Checker: parse error in type; type name `List' is >>>> unbound in: List" >>>> >>>> Is this a bug or am I missing something? >>>> >>>> --Spencer >>>> ____________________ >>>> Racket Users list: >>>> http://lists.racket-lang.org/users >>>> ____________________ >>>> Racket Users list: >>>> http://lists.racket-lang.org/users >>> >>> >>> ____________________ >>> Racket Users list: >>> http://lists.racket-lang.org/users > ____________________ Racket Users list: http://lists.racket-lang.org/users
