Re: [racket-users] Contract on a parameter’s value as a function precondition?

It turns out that the continuation mark keys and procedures for parameters aren’t really hidden away, so it ended up being pretty straight forward. Below is a minimal implementation of parameterization->. I’m happy to help integrate this into the racket/contract family once we figure out what’s

Re: [racket-users] Contract on a parameter’s value as a function precondition?

Does this do what you need? (define/contract (foo bar) (-> (or/c 1 #t "bar" (listof string?) (listof (or/c 'a 'b))) boolean?) #t) (foo 1) (foo #t) (foo "bar") (foo '("should work")) (foo '(a)) (foo '(b)) (foo '(b a b a a a)) (foo "should fail") Output: #t #t #t #t #t #t #t foo: contract

Re: [racket-users] Contract on a parameter’s value as a function precondition?

That sounds promising, yes. Not being familiar with the guts of parameters, is there any way to implement this as a derived concept using the existing support in chaperone-procedure? As far as I can tell, parameters do not expose the continuation marks they use, and they also create thread cells,

Re: [racket-users] Contract on a parameter’s value as a function precondition?

Yes, we worked with Matthew to implement the necessary hooks in procedure chaperones (see the 'mark options that were added to the return value of wrapper-proc). For the contracts we were writing, we ended up using these continuation marks directly. To implement what you're looking for, a

Re: [racket-users] Contract on a parameter’s value as a function precondition?

I think that Scott investigated adding support to chaperones that would make something like this work. Robby On Tue, Nov 22, 2016 at 10:16 PM, Alexis King wrote: > I have a function that requires a parameter be set to a value satisfying > a particular contract, but I

[racket-users] Contract on a parameter’s value as a function precondition?

I have a function that requires a parameter be set to a value satisfying a particular contract, but I don’t see any direct way to specify that constraint using the contract system. It seems possible to emulate using #:pre from ->* and ->i, but this has two problems: it doesn’t produce very good