% nacteni:
/* ['2.4.1_6.pl']. */
append([],L,L).
append([H|T1],L2,[H|T]) :- append(T1,L2,T).
% demonstracni vypis
% abychom se vyhli varovanim "Redefined static procedure ..."
:- dynamic
write_all_X/3,
start/0.
write_all_X(Goal,X,Name):-
call(Goal),write(' '),write(Name),write(' = '),write(X),nl,fail.
write_all_X(_,_,_).
write_all_XY(Goal,X,XName,Y,YName):-
call(Goal),write(' '),write(XName),write(' = '),write(X),
write(' '),write(YName),write(' = '),write(Y),
nl, fail.
write_all_XY(_,_,_,_,_).
start:-
write('Prace se seznamy - append'),nl,
write('-------------------------------'),nl, nl,
write('vicesmernost predikatu append:'),nl,
write('Vysledek volani "append([a,b],[c,d],L)":'),nl,
write_all_X(append([a,b],[c,d],L), L, 'L'),nl,
write('Vysledek volani "append(X,[c,d],[a,b,c,d ]).":'),nl,
write_all_X(append(X,[c,d],[a,b,c,d ]), X, 'X'),nl,
write('Vysledek volani "append(X,Y,[a,b,c])":'),nl,
write_all_XY(append(X,Y,[a,b,c]), X, 'X', Y, 'Y'),nl.
?-start.
:- retractall(write_all_X/3).
:- retractall(start/0).
Prace se seznamy - append
-------------------------------
vicesmernost predikatu append:
Vysledek volani "append([a,b],[c,d],L)":
L = [a,b,c,d]
Vysledek volani "append(X,[c,d],[a,b,c,d ]).":
X = [a,b]
Vysledek volani "append(X,Y,[a,b,c])":
X = [] Y = [a,b,c]
X = [a] Y = [b,c]
X = [a,b] Y = [c]
X = [a,b,c] Y = []
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