Variation

Program create variation without repeated list elements

Source: Guide to Prolog Programming (on-line tutorial)

Program source code: variation.pl

varia(0,_,[]).
varia(N,L,[H|Varia]):-N>0,N1 is N-1,delete(H,L,Rest),varia(N1,Rest,Varia).
 
delete(X,[X|T],T).
delete(X,[H|T],[H|NT]):-delete(X,T,NT).