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From: peter@ficc.ferranti.com (Peter da Silva)
Newsgroups: comp.lang.scheme
Subject: Re: Scheme as an extension language and call/cc
Message-ID: <AXI5NUG@xds13.ferranti.com>
Date: 29 Aug 90 00:01:17 GMT
References: <PK.90Aug21114528@kaarne.tut.fi> <409@data.UUCP>
Reply-To: peter@ficc.ferranti.com (Peter da Silva)
Distribution: comp
Organization: Xenix Support, FICC
Lines: 21

> {Seriously, if you need co-routines, non-blind backtracking, or have a
> timer interrupt and want to do multi-tasking, continuations are most
> useful.  The implementation is not hard if you are doing an
> interpreter and efficient runtime implementation technology for
> compiled systems is well known.}

	"Montage is not a proactical system. The CALL/CC construct
	 of Scheme, while powerful and portable, does not acheive the
	 performance necessary for the near real-time constraints
	 that a window system imposes. Specifically, in every one of
	 the dozen Scheme implementations that I have tested CALL/CC
	 allocates so much memory that most of the run time is spent
	 in the garbage collector."

		-- Paul Haahr,
		   "Montage: Breaking windows into small pieces",
		   USENIX conferance proceedings, Jun 11-15, 1990.

This is exactly the environment an extension language is needed for. For
what you need CALL/CC for in such a program CALL/CC is not fast enough.
Thus I would consider CALL/CC to be a luxury in this environment.
-- 
Peter da Silva.   `-_-'
+1 713 274 5180.   'U`
peter@ferranti.com