Maybe this line: https://github.com/racket/racket/blob/master/racket/collects/racket/contract/private/parametric.rkt#L105
should be: #:first-order (λ (c) (if (barrier-contract-positive? c) (barrier-contract-pred c) (λ (x) #t))) ? Robby On Tue, Nov 28, 2017 at 8:02 PM, Ben Greenman <[email protected]> wrote: > The other day, I wanted to write a contract for a function that takes > any kind of vector and does something depending on whether the vector > is mutable. The contract was basically the one below: > > ``` > #lang racket > > (define/contract (f v) > (parametric->/c [A] > (-> (or/c (vectorof A #:immutable #true) > (vectorof A #:immutable #false)) > any)) > (void)) > ``` > > When I try to call this function, I get an error "none of the branches > of the or/c matched". > > It looks like this error is because `contract-first-order-passes?` > returns #false if the vector I pass to `f` has any elements. > > Two questions: > > 1. Could `(contract-first-order-passes? ctc val)` return `#true` if > `ctc` is from a `parametric->/c` ? (I feel like it shouldn't but I > don't know why not) > > 2. If not, would `or/c` be better off using a > `contract-first-order-fails?` predicate? > > -- > 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 [email protected]. > For more options, visit https://groups.google.com/d/optout. -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
