Subject: Re: best standard? [was Re: RFC: Lisp/Scheme ...]
From: rpw3@rigden.engr.sgi.com (Rob Warnock)
Date: 2000/08/17
Newsgroups: comp.lang.lisp
Message-ID: <8ngd7n$hb56r$1@fido.engr.sgi.com>
Kent M Pitman  <pitman@world.std.com> wrote:
+---------------
| The issue, which really I'm the only one I've ever heard get excited about,
| is that call/cc gets one too few bits as an argument...
| ...two obvious ways, and probably some others.  The two ways I've cited are:
|  (1) add an extra arg to call/cc saying if you want a one-time use ...
|  (2) keep call/cc as it is, but make every continuation take an argument...
+---------------

Several Schemes agree with the general sentiments you voice, but have
chosen to:

   (3) Leave call/cc as it is, and add a separate primitive to reify
       "one-shot" continuations.

[MzScheme calls this "call/ec" a.k.a. "call-with-escaping-continuation".
It also provide the convenience macros "let/cc" & "let/ec". More info
at <URL:http://www.cs.rice.edu/CS/PLT/packages/doc/mzscheme/node86.htm>.]


-Rob

-----
Rob Warnock, 41L-955		rpw3@sgi.com
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