Greetings
The behaviour of call-with-semaphore doesn't appear to match the documentation,
or else I'm misunderstanding the documentation.
Consider:
(define (printit m)
(printf "msg begin:~a~%" m))
(define try
(let ((sema (make-semaphore 1)))
(λ (msg)
(call-with-semaphore sema
printit
;#f
msg))))
(try "second")
With #f commented out, I get (with Racket 5.3):
call-with-semaphore: procedure arity does not match extra-argument count
procedure: #<procedure:printit>
extra-argument count: 0
>
With #f uncommented, it works as expected:
Welcome to DrRacket, version 5.3 [3m].
Language: racket; memory limit: 128 MB.
msg begin:second
>
The documentation says:
(call-with-semaphore sema
proc
[ try-fail-thunk]
arg ...) → any
However it appears that the try-fail-chunk argument is not in fact optional.
----
Separately, it appears that CALL-WITH-SEMAPHORE returns the value that (proc
args…) returns. However the documentation doesn't actually say that. Is that
just an oversight, or is the return value of CALL-WITH-SEMAPHORE undefined?
Best wishes,
Norman
--
Norman Gray : http://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK
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