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<DIV>----- Original Message ----- </DIV>
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<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=matthias@ccs.neu.edu href="mailto:matthias@ccs.neu.edu">Matthias
Felleisen</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=jacobm@cs.uchicago.edu
href="mailto:jacobm@cs.uchicago.edu">Jacob Matthews</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A title=robby@cs.uchicago.edu
href="mailto:robby@cs.uchicago.edu">Robby Findler</A> ; <A
title=plt-scheme@list.cs.brown.edu
href="mailto:plt-scheme@list.cs.brown.edu">plt-scheme@list.cs.brown.edu</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, November 14, 2006 3:39
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [plt-scheme] Please help
test version 359.100</DIV>
<DIV><BR></DIV>
<DIV>I don't think this is relevant. The true question is
whether<BR><BR> (+ (for-each add1 '()) (for-each sub1 '()))<BR><BR>steps
to<BR><BR> (+ some-value some-value)<BR><BR>or to<BR><BR> (+
some-value some-different-value)<BR><BR>I believe that the second one is the
case already. -- Matthias</DIV>
<DIV><FONT face="Courier New" size=2></FONT> </DIV><FONT
face="Courier New" size=2></FONT></BLOCKQUOTE>
<DIV><FONT face="Courier New" size=2> Then why do I get: (eq? (for-each
add1 '()) (for-each sub1 '())) --> #t ?</FONT></DIV>
<DIV><FONT face="Courier New" size=2>(version 359.100-svn4nov2006) Greetings,
Jos Koot</FONT></DIV>
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<DIV><FONT face="Courier New" size=2></FONT><FONT face="Courier New"
size=2></FONT><FONT face="Courier New" size=2></FONT><FONT face="Courier New"
size=2></FONT><BR><BR><BR>On Nov 13, 2006, at 6:52 PM, Jacob Matthews
wrote:<BR><BR>> On Nov 13, 2006, at 5:31 PM, Robby Findler
wrote:<BR>><BR>>> Is "some object" allowed to be multiple values or
not? That text<BR>>> suggests not.<BR>><BR>> "Types are associated
with values (also called objects) rather than <BR>> with variables"
(section 1.1) seems to be the only definition of <BR>> what an
'object' is. I think it's clear that they are saying that <BR>>
values are also called objects, and that by the normal rules of <BR>>
English we can conclude that the singular 'object' means the same
<BR>> thing as the singular 'value'. So the question becomes, are
<BR>> multiple values the same thing as a single value? The report
seems <BR>> to think not (I'm going here by the descriptions of the
values and <BR>> call-with-values functions in section 6.4), though
it plays its <BR>> usual trick of simply not defining what happens if
a context <BR>> expects a single value and it receives multiple
ones.<BR>><BR>> Applying this back to the original question, I think we
have to <BR>> conclude that for-each is supposed to be able to be
called in <BR>> contexts that expect exactly one value. In Schemes
like PLT Scheme <BR>> where contexts that expect one value signal an
error if they <BR>> receive some other number, then it's a violation
of R5RS for for- <BR>> each to behave the way 359.100 did; but for Schemes
like Bigloo <BR>> that have coercion rules that take a multi-value
return to a single- <BR>> value context, it's not a
violation.<BR>><BR>> -jacob<BR>><BR>> (I actually wrote up a
version of this before and then deleted it, <BR>> thinking it was too
technical for anybody to care about ... looks <BR>> like I was wrong.
:) )<BR><BR>_________________________________________________<BR> For
list-related administrative tasks:<BR> <A
href="http://list.cs.brown.edu/mailman/listinfo/plt-scheme">http://list.cs.brown.edu/mailman/listinfo/plt-scheme</A></DIV></BLOCKQUOTE></BODY></HTML>