Quick answer is to replace (define-type (Fingertree a) (U Empty (Single a) (Deep a))) With (struct: (a) Fingertree ((v : (U Empty (Single a) (Deep a)))))
Still looking into understanding what is going on, but I believe you will need to introduce a Rec somewhere to get it how you want. On Wed, Apr 10, 2013 at 6:27 PM, Anthony Carrico <acarr...@memebeam.org> wrote: > I've been reading about fingertrees, and I figure the best way to > understand is to implement. This is my first experience with typed > racket. Are nested datatypes supported? > > This is my first try: > > typed-fingertree.rkt:19:48: Type Checker: Structure type constructor > Deep applied to non-regular arguments ((U (Node2 a) (Node3 a))) > > #lang typed/racket > > (struct: (a) Digit1 ((v0 : a))) > (struct: (a) Digit2 ((v0 : a) (v1 : a))) > (struct: (a) Digit3 ((v0 : a) (v1 : a) (v2 : a))) > (struct: (a) Digit4 ((v0 : a) (v1 : a) (v2 : a) (v3 : a))) > (define-type (Digit a) (U (Digit1 a) (Digit2 a) (Digit3 a) (Digit4 a))) > > (struct: (a) Node2 ((v0 : a) (v1 : a))) > (struct: (a) Node3 ((v0 : a) (v1 : a) (v2 : a))) > (define-type (Node a) (U (Node2 a) (Node3 a))) > > (struct: Empty ()) > (struct: (a) Single ((v : a))) > (struct: (a) Deep ((left : (Digit a)) > (spine : (Fingertree (Node a))) > (right : (Digit a)))) > > (define-type (Fingertree a) (U Empty (Single a) (Deep a))) > > Thank you! > > -- > Anthony Carrico > > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > ____________________ Racket Users list: http://lists.racket-lang.org/users
