7l7w-prolog-day2

factorial.pl

% -*- mode: prolog; -*-
fact(1, 0).
fact(F, N) :-
        N > 0,
        N1 is N - 1,
        fact(F1, N1),
        F is F1 * N.

fibonacci.pl

% -*- mode: prolog; -*-
fib(0, 0).
fib(1, 1).
fib(F, N) :-
        N > 1,
        N1 is N - 1,
        N2 is N - 2,
        fib(F2, N2),
        fib(F1, N1),
        F is F1 + F2.

min.pl

% -*- mode: prolog; -*-
min(X, [X]).
min(X, [A, B]) :-
        A < B, X = A.
min(X, [A, B]) :-
        A >= B, X = B.
min(X, [Head|Tail]) :-
        min(Tmin, Tail),
        min(X, [Head, Tmin]).

penguin.pl

% -*- mode: prolog; -*-
bird(kiwi).
bird(duck).
fly(duck).

penguin1(X) :-
    \+fly(X), bird(X).

penguin2(X) :-
    bird(X), \+fly(X).

selection_sort.pl

% -*- mode: prolog; -*-
min(X, [X]).
min(X, [A, B]) :-
        A < B, X = A.
min(X, [A, B]) :-
        A >= B, X = B.
min(X, [Head|Tail]) :-
        min(Tmin, Tail),
        min(X, [Head, Tmin]).

selection_sort([], []).
selection_sort(L, [X|S]) :-
        min(X, L),
        delete(L, X, R),
        selection_sort(R, S).


        

tower_of_hanoi.pl

% -*- mode: prolog; -*-
hanoi(0, _, _, _).
hanoi(N, A, B, C) :-
        N > 0,
        N1 is N - 1,
        hanoi(N1, A, C, B),
        write((move, N, from, A, to, B)), nl,
        hanoi(N1, C, B, A).

http://d.hatena.ne.jp/passingloop/20110917/seven_languages_in_seven_weeks_chapter_4_prolog_self_study