Hi,
i am trying to understand how nack-guard-evt works. Therefore i created
the appended test program. Sometimes it stops with the error message and
sometimes it prints the three values. It is clear to me what the error
means and why it is raised.
What i am not understanding is, why the nack generator is not run every
time sync is called. I would have expected from the docs that it is run on
every sync.
Can someone clarify why my assumptions are wrong and how nack-guard-evt is
expected to behave?
Related question: The docs for the function talk abound 'proc', should it
be 'generator'?
Tobias
;; -----------------------------
#lang racket
(define nack #f)
(sync (handle-evt
always-evt
(lambda (_) 'ALWAYS))
(nack-guard-evt
(lambda (e)
(set! nack e)
never-evt)))
nack
(printf "~a\n" (sync/timeout 0. nack))
'ALWAYS
#f
. . sync/timeout: contract violation
expected: evt?
given: #f
argument position: 2nd
other arguments...:
0.0
OR
'ALWAYS
#<evt>
#<void>
--
---------------------------------------------------------
Tobias Hammer
DLR / Robotics and Mechatronics Center (RMC)
Muenchner Str. 20, D-82234 Wessling
Tel.: 08153/28-1487
Mail: tobias.ham...@dlr.de
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