added example 2.4.1_6

2.4.1_6.pl

+% 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).

2.4.1_6.py

+#!/usr/bin/env python
+# encoding=utf-8 (pep 0263)
+
+def append(xs, ys):
+    if not xs:
+        return ys
+    else:
+        return [xs[0]] + append(xs[1:], ys)
+
+def append_anyXs(ys, zs):
+    if ys == zs:
+        return []
+    else:
+        if zs:
+            return [zs[0]] + append_anyXs(ys, zs[1:])
+        else:
+            raise ValueError("ys neni sufixem zs")
+
+def append_anyXsYs(zs):
+    yield ([], zs)
+    if zs:
+        for xs, ys in append_anyXsYs(zs[1:]):
+            yield ([zs[0]] + xs, ys)
+
+# demonstracni vypis
+if __name__ == "__main__":
+    print("Prace se seznamy - append")
+    print("-------------------------------\n")
+    print("vicesmerne implementace funkce append:\n")
+    print("Vysledek volani append(['a', 'b'], ['c', 'd']): %s\n" % \
+            append(['a', 'b'], ['c', 'd']))
+
+    print("Vysledek volani append_anyXs(['c', 'd'], ['a', 'b', 'c', 'd']): %s\n" % \
+            append_anyXs(['c', 'd'], ['a', 'b', 'c', 'd']))
+
+    print("Vysledek volani append_anyXsYs(['a', 'b', 'c']): %s\n" % \
+            list(append_anyXsYs(['a', 'b', 'c'])))