[plt-scheme] Check-error

It's not check-expect/check-error that's at fault here. It is the  
widely spread belief that coroutines are plain old functions in Scheme.

Try this program instead:

> #lang scheme
> (require test-engine/scheme-tests)
>
> (define (run coroutine val)
>   (let ([x (coroutine val)])
>     (if (exn:fail? x)
>         (raise x)
>         x)))
>
> (define coroutine4
>   (letrec
>       ((local-state
>         (lambda (first-resume-value)
>           (toggle 0)
>           (toggle 1)
>           (toggle 2)
>           (toggle (make-exn:fail "expired coroutine" (current- 
> continuation-marks)))))
>        (toggle
>         (lambda (return/resume-value)
>           (call-with-current-continuation
>            (lambda (cc)
>              (let ((old-state local-state))
>                (set! local-state cc)
>                (old-state return/resume-value)))))))
>     toggle))
>
> (check-expect (run coroutine4 'ignored) 0)
> (check-expect (run coroutine4 'ignored) 1)
> (check-expect (run coroutine4 'ignored) 2)
> (check-error  (run coroutine4 'ignored) "expired coroutine")
>
> (test)




On Apr 15, 2010, at 5:04 AM, Jos Koot wrote:

> Is it me or check-error who is wrong?
> Jos
>
> #lang scheme
> (require test-engine/scheme-tests)
>
> (define coroutine4
>  (letrec
>   ((local-state
>     (lambda (first-resume-value)
>      (toggle 0)
>      (toggle 1)
>      (toggle 2)
>      (error "expired coroutine")))
>    (toggle
>     (lambda (return/resume-value)
>      (call-with-current-continuation
>       (lambda (cc)
>        (let ((old-state local-state))
>         (set! local-state cc)
>         (old-state return/resume-value)))))))
>   toggle))
>
> (check-expect (coroutine4 'ignored) 0)
> (check-expect (coroutine4 'ignored) 1)
> (check-expect (coroutine4 'ignored) 2)
> (check-error (coroutine4 'ignored) "expired coroutine")
>
> (test)
>
> Welcome to DrScheme, version 4.2.5.7-svn10apr2010 [3m].
> Language: scheme [custom]; memory limit: 2000 MB.
> bug: collects\test-engine\scheme-tests.ss:157:0: expired coroutine
> Ran 4 checks.
> 1 of the 4 checks failed.
>
>         check-expect encountered the following error instead of the  
> expected value, 0.
>    :: expired coroutine
>  At line 21 column 0
> >
>
> _________________________________________________
>  For list-related administrative tasks:
>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme