Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rice!news
From: gateley@datura.rice.edu (John Gateley)
Newsgroups: comp.lang.scheme
Subject: Re: Functionality and implicit arg's (call/cc & referential transparency)
Message-ID: <1990Aug30.164457.26199@rice.edu>
Date: 30 Aug 90 16:44:57 GMT
References: <583@array.UUCP> <1990Aug24.212055.8368@nixtdc.uucp> <1543@anaxagoras.ils.nwu.edu>
Sender: news@rice.edu (News)
Organization: Rice University, Houston
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In article <1543@anaxagoras.ils.nwu.edu> krulwich@ils.nwu.edu (Bruce Krulwich) writes:
>        (define ...
>       ...
>           (let -loop-name- (... vars ...)
>            ...
>               (another-proc ...
>                 (lambda (arg) (-loop-name- arg))  ; success continuation
>                 (lambda () (-loop-name- var))     ; failure continuation
>                 )  ))

The question about whether or not the above is functional hinges on
one issue - how is the let loop implemented (heap space was mentioned
in the article). If it is implemented with a let/set! approach (the
normal macroexpansion for letrec), then it is NOT functional. If it is
implemented with Y, then it is functional. However, I don't think you
can translate call/cc in to some magic combinator Z so that it too is
functional, it is still dependent on context.

John
gateley@rice.edu