Matthias Felleisen wrote at 06/09/2012 11:24 AM:
Neil, do you mean something like this:
Robby answered my question in a subsequent message: the core contract
combinators don't support saying arity "two arguments, possibly more,
but not necessarily arbitrarily more".
Regarding what I'm doing with my code... I didn't mean all the values
from a history from multiple applications of P1, but all the values from
a multiple-value-return of a single application of P1. (See example
below.) And I preferred to do it without "set!". And I'd prefer to
make each of the multiple-value-return values from P1 a separate
argument to P2. My code works close enough to how I want it to
The example below shows how I want the values passed from P1 to P2.
(Note: the "display" forms represent nested contexts, though they don't
show it, such as for handling unwinds and exceptions, so what they
represent is not just interleaved expressions.)
#lang racket/base
(define (f p1 p2)
(display "do-thing-1-here\n")
(let ((multiple-value-result-of-p1 (call-with-values (lambda ()
(p1 'a))
list)))
(display "do-thing-2-here\n")
(begin0 (apply p2 'b 'c multiple-value-result-of-p1)
(display "do-thing-3-here\n"))))
(f (lambda args (printf "~S\n" `(p1 ,@args)) (values 'd 'e 'f))
(lambda args (printf "~S\n" `(p2 ,@args))))
Outputs:
do-thing-1-here
(p1 a)
do-thing-2-here
(p2 b c d e f)
do-thing-3-here
Neil V.
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