Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!rutgers!usc!wuarchive!uunet!ogicse!novick
From: novick@ogicse.ogi.edu (David G. Novick)
Newsgroups: comp.lang.prolog
Subject: Re: Abstract Type in Prolog ?
Message-ID: <15580@ogicse.ogi.edu>
Date: 3 Jan 91 19:26:42 GMT
References: <1991Jan3.154717.27057@watserv1.waterloo.edu>
Organization: Oregon Graduate Institute (formerly OGC), Beaverton, OR
Lines: 25
In-reply-to: yfeng@watnow.waterloo.edu's message of 3 Jan 91 15:47:17 GMT

Following up yfeng@watnow.waterloo.edu's inquiry about abstract
data types in Prolog, here are a couple of definitions
I've used.  Note that these do *not* create or necessarily
reference persistent objects.

% define ADT stack with usual operations
%
s_new([]).
s_push(Elt,Stack,[Elt|Stack]).
s_pop([_|Stack],Stack).
s_top(Elt,[Elt|_]).

% define ADT queue with usual operation
%
q_new([]).
q_insert(Elt,Q,Q2) :- append(Q,[Elt],Q2).
q_next(Elt,[Elt|_]).
q_delete([_|Q],Q).

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