tasks a-s

Task/Perfect-numbers/Prolog/perfect-numbers-1.pro

@@ -0,0 +1,14 @@
+tt_divisors(X, N, TT) :-
+	Q is X / N,
+	(   0 is X mod N -> (Q = N -> TT1 is N + TT;
+                             TT1 is N + Q + TT);
+            TT = TT1),
+	(   sqrt(X) > N + 1 -> N1 is N+1, tt_divisors(X, N1, TT1);
+	    TT1 = X).
+
+perfect(X) :-
+	tt_divisors(X, 2, 1).
+
+perfect_numbers(N, L) :-
+	numlist(2, N, LN),
+	include(perfect, LN, L).

Task/Perfect-numbers/Prolog/perfect-numbers-2.pro

@@ -0,0 +1,37 @@
+:- use_module(library(lambda)).
+
+is_divisor(V, N) :-
+	0 =:= V mod N.
+
+is_perfect(N) :-
+	N1 is floor(N/2),
+	numlist(1, N1, L),
+	f_compose_1(foldl((\X^Y^Z^(Z is X+Y)), 0), filter(is_divisor(N)), F),
+	call(F, L, N).
+
+f_perfect_numbers(N, L) :-
+	numlist(2, N, LN),
+	filter(is_perfect, LN, L).
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% functionnal predicates
+
+%% foldl(Pred, Init, List, R).
+%
+foldl(_Pred, Val, [], Val).
+foldl(Pred, Val, [H | T], Res) :-
+	call(Pred, Val, H, Val1),
+	foldl(Pred, Val1, T, Res).
+
+%% filter(Pred, LstIn, LstOut)
+%
+filter(_Pre, [], []).
+
+filter(Pred, [H|T], L) :-
+	filter(Pred, T, L1),
+	(   call(Pred,H) -> L = [H|L1]; L = L1).
+
+%% f_compose_1(Pred1, Pred2, Pred1(Pred2)).
+%
+f_compose_1(F,G, \X^Z^(call(G,X,Y), call(F,Y,Z))).