Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!rutgers!iuvax!pur-ee!uiucdcs!uiucdcsm!mccaugh
From: mccaugh@uiucdcsm.cs.uiuc.edu
Newsgroups: comp.lang.prolog
Subject: Prolog Is Semi-Procedural
Message-ID: <5500005@uiucdcsm>
Date: 28 May 88 06:38:00 GMT
Lines: 12
Nf-ID: #N:uiucdcsm:5500005:000:488
Nf-From: uiucdcsm.cs.uiuc.edu!mccaugh    May 28 01:38:00 1988


I submit that "prolog" - the so-called "logic-programming" language - is
(among other disclaimers) NOT altogether the "declarative" non-procedural
 language it is advertised to be. Case in point:

 sum(0,0).
 sum(N,M) :- N1 = N-1, sum(N1,M1), M = M1+N.

 In a truly non-procedural (i.e. (I anticipate controversy here) non-
 deterministic) language, the test: N>0 should not be necessary, and yet
 (as we know), it must appear to avoid stack-overflow (in CPROLOG, UNSW-
 PROLOG, anyway).