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Article #5394

Multiple values

#5394
From: Cesar Quiroz
Date: Mon, 28 Mar 1988 18:18
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Gaynor@porthos asks
:How would Scheme's continuations fit into the area of multiple
:return values?

In a capsule:
1- Returning == Calling a continuation
so
2- Returning multiple values == Calling a continuation with multiple
arguments.

So, if `k' is the normal continuation of `f', and `f' tries to
return `v1', `v2', ..., you could model

                         (values v1 v2 ...)

as

                           (k v1 v2 ...)

I believe Scheme doesn't have this class of continuations
(Scheme's continuations take only one argument). However, that this
modification is possible has been known for a long time (at least
since Steele's work in RABBIT, which is as old as one can get
relative to Scheme), so I wouldn't be surprised if at least one
implementation has supported multiple values.  Actually, this has
been known to denotational semantics people for even longer.

Cesar

-- 
Cesar Augusto  Quiroz Gonzalez
Department of Computer Science     ...allegra!rochester!quiroz
University of Rochester            or
Rochester,  NY 14627               quiroz@cs.rochester.edu
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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!bbn!rochester!quiroz
References: <12176@brl-adm.ARPA> <1988Mar11.215238.976@utzoo.uucp> <719@l.cc.purdue.edu> <10763@mimsy.UUCP> <3177@haddock.ISC.COM> <18580@think.UUCP> <Mar.28.12.43.35.1988.1511@porthos.rutgers.edu>

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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!bbn!rochester!quiroz
From: quiroz@cs.rochester.edu (Cesar Quiroz)
Newsgroups: comp.lang.misc
Subject: Multiple values
Message-ID: <8121@sol.ARPA>
Date: 28 Mar 88 18:18:22 GMT
References: <12176@brl-adm.ARPA> <1988Mar11.215238.976@utzoo.uucp> <719@l.cc.purdue.edu> <10763@mimsy.UUCP> <3177@haddock.ISC.COM> <18580@think.UUCP> <Mar.28.12.43.35.1988.1511@porthos.rutgers.edu>
Reply-To: quiroz@cs.rochester.edu (Cesar Quiroz)
Organization: U of Rochester, CS Dept, Rochester, NY 14627
Lines: 35