This works if you expand the use of Iteratee within the definition of Continuation. Mutually-recursive polymorphic types are problematic, but Continuation is only actually singly-recursive. You can still have the definition Iteratee for outside use.
Carl Eastlund #lang typed/racket/base ;; Inputs (define-type (Stream D) (U (Datum D) 'Nothing 'EOS)) (struct: (D) Datum ([iota : D])) ;; Iteratee (define-type (Iteratee D A) (U (Done D A) (Continuation D A))) (struct: (D A) Done ([accum : A] [stream : (Stream D)])) (struct: (D A) Continuation ([resume : ((Stream D) -> (U (Done D A) (Continuation D A)))])) On Thu, Jul 19, 2012 at 6:07 PM, Ray Racine <ray.rac...@gmail.com> wrote: > #lang typed/racket/base > > ;; Inputs > (define-type (Stream D) (U (Datum D) 'Nothing 'EOS)) > (struct: (D) Datum ([iota : D])) > > ;; Iteratee > (define-type (Iteratee D A) (U (Done D A) (Continuation D A))) > (struct: (D A) Done ([accum : A] [stream : (Stream D)])) > (struct: (D A) Continuation ([resume : ((Stream D) -> (Iteratee D A))])) > > 1. How can I get the recursive nature of Iteratee and Continuation to type > check? > 2. Ideally, but not necessary, like to define Continuation as a > define-struct/exec: > > Thanks, > > Ray ____________________ Racket Users list: http://lists.racket-lang.org/users
