Union

Description

Finding the union of two lists

Source: The Art of Prolog

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Program source code: union.pl

Listing

/*
   union(Xs,Ys,Us) :- Us is the union of the elements in Xs and Ys. 
*/
 
union([X|Xs],Ys,Us) :- member(X,Ys), union(Xs,Ys,Us).
union([X|Xs],Ys,[X|Us]) :- nonmember(X,Ys), union(Xs,Ys,Us).
union([],Ys,Ys).
/*
   nonmember(X,Xs) :- X is not a member of the list Xs.
*/
     nonmember(X,[Y|Ys]) :- X \== Y, nonmember(X,Ys).
     nonmember(X,[]).
 
 
%  Program 13.1    Finding the union of two lists

Comments

pl/prolog/pllib/union.txt · ostatnio zmienione: 2017/07/17 08:08 (edycja zewnętrzna)
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