On Mon, Nov 18, 2019 at 12:23 PM David Storrs <david.sto...@gmail.com> wrote:
> > > On Mon, Nov 18, 2019 at 10:09 AM Sam Tobin-Hochstadt <sa...@cs.indiana.edu> > wrote: > >> >> Third, your version with structs can't work because you can't tell >> what type a function expects -- that information is not there at >> runtime. >> > > If there is a contract assigned to a function, is it possible to get that > function and analyze it? > Correction: Get that *contract* and analyze it. > >> Sam >> >> On Wed, Nov 6, 2019 at 2:51 PM bedeke <bed...@hotmail.com> wrote: >> > >> > Hello, >> > >> > I was trying to type some polymorphic classes but I got stuck early on >> making a polymorphic subclass >> > >> > #lang typed/racket/base >> > >> > ;*****1***** >> > (require typed/racket/class) >> > >> > (define-type (C-class A)(Class [init-field [x A]])) >> > >> > (define C1% >> > (class object% >> > #:∀ (A) >> > (init-field [x : A]) >> > (super-new))) >> > >> > (define C2% >> > (class (inst C1% A) >> > #:∀ (A) >> > (super-new))) >> > >> > (new (inst C2% Integer) [x 4]) >> > >> > C1% is recognised as a C-class, but explicitly calling C1% a C-class >> (omitting the #:forall (A) ) doesn't work >> > In the next step I don't seem to find the right way to make C2% a >> polymorphic subclass of C1% >> > >> > >> > >> > Having failed that I went with structures. This I got mostly working, >> but I would like to have some niceties. >> > One was to parameterize a structure, but this lead to a problem of not >> being able to check some >> > types at runtime. I thought I got close, but I stranded on getting >> fields of structures without knowing the instantiation type >> > ;*****2***** >> > (struct (A) S ([f1 : (-> A A A)] >> > [f2 : (-> A Boolean : A)])) >> > >> > (: S-of-type? (-> (-> Any Boolean : A) Any Boolean >> > : #:+ (implies #t (S A)) >> > #:- (implies #f (! (S A))))) >> > (define (S-of-type? fct A) >> > (and (S? A) (eq? fct (S-f2 A)))) >> > ; ^ how can I acces a field of this polymorfic >> struct >> > >> > >> > >> > And another thing I tried but failed to get working is to sub-type a >> structure based >> > on a narrower type for one of the fields. >> > ;*****3***** >> > (struct (A) B ([f1 : (Vectorof A)] >> > [f2 : Integer]) >> > #:transparent) >> > >> > (: B1? (All (A) (-> (B A) Boolean))) >> > (define (B1? b)(= (B-f2 b) 1)) >> > (define b (B (vector 3) 1)) >> > (assert b B1?) >> > b >> > (define-type B1 B1?) >> > ;(define-new-subtype B1 B1?) >> > ;(define-type B1 (All (A)(Struct (B (Vectorof A) 1)))) >> > >> > >> > Are any of these things doable? Or are there better ways to tackle this >> problems? >> > >> > >> > What I got working is in >> > >> https://github.com/bdeket/polynomials/blob/alg-dic-pol/polynomials/math/private/polynomial/poly-struct.rkt >> (WIP) >> > >> > Kind regards, >> > Bert >> > >> > -- >> > You received this message because you are subscribed to the Google >> Groups "Racket Users" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an email to racket-users+unsubscr...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/racket-users/3c4bcedd-5677-4972-97a3-04e33ca30816%40googlegroups.com >> . >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Racket Users" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to racket-users+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/racket-users/CAK%3DHD%2BaE1h7tYT4nyRoAgUhVCWCNmJfvJ5V5QTzCcbwv_kvJhA%40mail.gmail.com >> . >> > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/CAE8gKodq4Y_sFnCdTXtOP4OrZxckhajxejOOqwyN3j0wTe7_EQ%40mail.gmail.com.
