Article View: comp.lang.prolog
Article #3901Re: existential quantification in bagof
From: gerdeman
Date: Thu, 09 Feb 1989 22:17
Date: Thu, 09 Feb 1989 22:17
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1313 bytes
Yes 209 and 201 should be _209 and _201. It occurred to me that I
should have given a more extended example of this behavior of 'findall'.
Consider the following:
?- findall(X,member(X,[Y,Z,Y],S).
X = _54
Y = _98
Z = _111
S = [_230,_222,_214]
Here the variables are not only replaced, they're not even replaced
consistently. Serious bugs are imaginable. But in the following case,
the variables are replaced consistently:
?- findall(X,X = [Y,Z,Y],S).
X = _54
Y = _84
Z = _97
S = [[_193,_195,_193]]
This behavior is potentially useful. But, is it intended? Does any other
Prolog work this way, or is TI-Prolog unique?
-- Dale Gerdemann
University of Ill
Dept. of Linguistics
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!uxc!uxc.cso.uiuc.edu!clio!gerdeman From: gerdeman@clio.las.uiuc.edu Newsgroups: comp.lang.prolog Subject: Re: existential quantification in bagof Message-ID: <16400005@clio> Date: 9 Feb 89 22:17:00 GMT References: <1584@kulcs.kulcs.uucp> Lines: 29 Nf-ID: #R:kulcs.kulcs.uucp:1584:clio:16400005:000:841 Nf-From: clio.las.uiuc.edu!gerdeman Feb 9 16:17:00 1989