As Ben pointed out, if the exception is a `real exn:fail:contract:blame`,
you don't even need to parse the message string:
#lang racket
(define/contract (wants-exact x)
(-> exact? exact?)
x)
(define/contract (wants-inexact x)
(-> inexact? inexact?)
x)
(define (show-which-was-violated x)
(with-handlers ([exn:fail:contract:blame?
(λ (e)
(blame-value
(exn:fail:contract:blame-object e)))])
(wants-exact x)
(wants-inexact x)))
(map show-which-was-violated '(1 1.0)) ;; '(wants-inexact wants-exact)
-Philip
On Mon, Mar 25, 2019 at 1:11 PM James Platt <j...@biomantica.com> wrote:
>
> On Mar 25, 2019, at 12:49 PM, Matthias Felleisen wrote:
>
> > See how precise the exn message is: 2nd arg of 1st arg of f ~~ not a
> boolean?
>
> Okay. So the exn message is generated in a systematic way which I can
> count on. I didn't realize that. Thanks.
>
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