On Mon, May 18, 2020 at 04:51:26PM -0400, Sam Tobin-Hochstadt wrote: > The systematic way to do it is to use `inst`. > > Here's the first example: > > (define hash-list : (Listof (Pair Symbol Natural)) (list)) > ((inst sort (Pair Symbol Natural) String) hash-list string<? #:key (λ > ((p : (Pair Symbol Natural))) (symbol->string (car p))) #:cache-keys? > #t) > > This program works already, but I wasn't sure what the `y` binding was > doing in your second example:
I don't either. It was originally someone else's program, which I'm coverting to typed Racket in order to understand it better. -- hendrik > > (for*/list : (Listof (Pair Symbol Natural)) ((p : (Pair Symbol > Natural) (in-list hash-list)) > (k : Symbol (in-value (car p))) > (v : Natural (in-value (cdr p))) > #:when (not (= v 1)) > ) > (cons k v)) > > Sam > > On Mon, May 18, 2020 at 4:33 PM Hendrik Boom <hend...@topoi.pooq.com> wrote: > > > > I keep getting the messages like > > > > Type Checker: Inference for polymorphic keyword functions not supported in: > > (sort hash-list string<? #:key (λ ((p : (Pair Symbol Natural))) > > (symbol->string (car p))) #:cache-keys? #t) > > > > or > > > > Type Checker: Polymorphic function `cons' could not be applied to arguments: > > Types: a (Listof a) -> (Listof a) > > a b -> (Pairof a b) > > Arguments: (U Exact-Nonnegative-Integer Symbol) (Listof (Pairof Symbol > > Nonnegative-Integer)) > > Expected result: (Listof (Pairof Symbol Nonnegative-Integer)) > > in: (for*/list : (Listof (Pair Symbol Natural)) ((p : (Pair Symbol > > Natural) (in-list (hash->sorted-list pname-map))) (k : Symbol (in-value > > (car p))) (v : Natural (in-value (cdr p))) #:when (not (= v 1)) (y (list k > > v))) y) > > > > Is there some systematic way to code this explicitly so it > > doesn't have to try guesswork? (hich it refuses to do) > > > > And is it really unable to figure out that an > > Exact-Nonnegative-Integer is a Nonnegative-Integer? > > > > -- hendrik > > > > -- > > 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/20200518203342.4vcvrsrvkmld4tmh%40topoi.pooq.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/20200518221533.uwflu2ulyzeolcmv%40topoi.pooq.com.
