Pack with some functions in PROLOG lang

common.pl

append([],L,L):-!.
append([H|T1], L, [H|T3]):- append(T1,L,T3).

erase(X,L1,L2):- append(A, [X|D], L1),
    			 append(A, D, L2).

fatorial(0,1):-!.
fatorial(N,F):- N1 is N-1,
    			fatorial(N1,F1),
    			F is N*F1.

max(X,Y,X):- X>=Y,!.
max(_,Y,Y).


appendNotRepeated(X,L,L):- 	in(X,L),!.
appendNotRepeated(X,L,[X|L]).
in(X,[X|_]):- !.
in(X,[_|Y]):- in(X,Y).

len([],0):-!.
len([_|Y],N):-  len(Y,NY),
    			N is NY+1.

imprime(1):- write('um').

hr(0):- write('-'),!.
hr(N):- write('-'), N1 is N-1, hr(N1).


aluno(pedro,20).
aluno(carlos,141).
aluno(zezin,11).
/* findall(X, aluno(X,_), L) Mostra todas as declaracoes no formato lista*/

/*
 * Common Methods
 */

/*
 * Notes:
 * O corte vermelho é usado para simular uma condicional
 * de caso contrário. Dessa forma, ele executa a linha
 * que esta se for verdade ignorando a segunda
 */

length.pl

comprimento([],0).
comprimento([_|T],S):- 	comprimento(T,S1),
    					S is S1+1,!.
sigma([],0).
sigma([H|T],R):-	sigma(T,R1),
    				R is H+R1,!.

swish.pl

nota(joao,2.0).

situacao(N,"aprovado"):- nota(N,S), S >= 7,!.
situacao(N,"recuperacao"):- nota(N,S), S >= 5, !.
situacao(_,"reprovado").



/******************************************************/
pertence(X, [X|_]):- !.
pertence(N, [_|L]):- pertence(N,L).



uniao([], L, [_|L]).
uniao([A|B], C, [A|_]):- 
    not( pertence(A,C) ),
    uniao(B, C, _).