Path: utzoo!yunexus!yetti!asst-jos
From: asst-jos@yetti.UUCP (Jonathan)
Newsgroups: comp.lang.prolog
Subject: Ranges of values in Cprolog
Message-ID: <242@yetti.UUCP>
Date: 4 May 88 18:49:25 GMT
Article-I.D.: yetti.242
Posted: Wed May  4 14:49:25 1988
Reply-To: asst-jos@yetti.UUCP (Research Assistants--Jonathan)
Organization: York U. Computer Science
Lines: 49


	I am working with C-prolog 1.5, and have implemented the following
predicate for sets. (I use lists to implement sets)

:- op(500, yfx, in).

X in [X|Rest].
X in [Y|Rest] :- X in Rest.

?- 3 in [1,2,3].

yes
?- X in [1,2,3,4].
X = 1;
X = 2;
X = 3;
X = 4;
no
?-

I use this (in conjunction with higher level predicates) to return the 
state of a set of variables, one at a time, (ie. on failure, as in setof/3).
I would to implement the this 'in' operator to allow for the following:
	(The '..' would have the same meaning as it does in Pascal).


?- X in [1 .. 100].
X = 1;
X = 2;
X = 3;
  .
  .
  .
X = 100;
no
?-


Unfortunately, I keep running into problems when attempting this, and I am 
tired of hitting my head against a brick wall. Any suggestions???


Thanks in advance.

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Jeffrey Klein                 BITNET: PROJ15@YUSOL
York University                 UUCP: ...!utzoo!yunexus!yuyetti!asst-jos
Toronto, Ontario  
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