gistfile1.pl

first([X|_], X).
second([_,X|_], X).

nth(1, [X|_], X).
nth(N, [_|L], X) :-
  N > 1, N1 is N-1, nth(N1, L, X).

len([], 0).
len([_|L], N) :-
  len(L, N1), N is N1+1.

max_list([X], X).
max_list([X|L], M) :-
  max_list(L, M1), M is max(X, M1).

rev_range(0, []).
rev_range(N, [N|L1]) :-
  N > 0, N1 is N-1,
  rev_range(N1, L1).

range(I, N, []) :- I > N.
range(I, N, [I|L1]) :-
  I =< N, I1 is I+1,
  range(I1, N, L1).

collatz(1, [1]).
collatz(N, [N|L1]) :-
  N > 1, N mod 2 =:= 0, N1 is N//2, collatz(N1, L1).
collatz(N, [N|L1]) :-
  N > 1, N mod 2 =:= 1, N1 is N*3+1, collatz(N1, L1).

inc_list([], []).
inc_list([X|L], [X1|L1]) :-
  X1 is X+1, inc_list(L, L1).

replace([], []).
replace([X|L], [X1|L1]) :-
  rule(X, X1),
  replace(L, L1).

rule(i, '私').
rule(you, 'あなた').
rule(have, '持つ').
rule(love, '愛する').
rule(a, '一つの').
rule(pen, 'ペン').
rule(book, '本').

append([], Y, Y).
append([X|Xs], Y, [X|Zs]) :- append(Xs, Y, Zs).

last(L, X) :- append(_, [X], L).

memb(X, L) :- append(_, [X|_], L).

member(X, [X|_]).
member(X, [_|L]) :- member(X, L).

common([], _, []).
common([X|L], M, [X|L1]) :-
  member(X, M),
  !,
  common(L, M, L1).
common([_|L], M, L1) :-
  common(L, M, L1).

reverse([], []).
reverse([X|L], R) :-
  reverse(L, R1),
  append(R1, [X], R).

rev(L, R) :- rev(L, [], R).
rev([], R, R).
rev([X|L], Y, R) :- rev(L, [X|Y], R).

palindrome(L) :- reverse(L, L).

permutation([], []).
permutation(L, [X|L2]) :-
  del(X, L, L1),
  permutation(L1, L2).

del(X, [X|L], L).
del(X, [Y|L], [Y|L1]) :-
  del(X, L, L1).

slow_sort(L, L1) :-
  permutation(L, L1),
  ordered(L1).

ordered([]).
ordered([_]).
ordered([X,Y|L]) :-
  X =< Y,
  ordered([Y|L]).

qsort([], []).
qsort([X|L], S) :-
  partition(L, X, L1, L2),
  qsort(L1, S1),
  qsort(L2, S2),
  append(S1, [X|S2], S).

partition([], _, [], []).
partition([Y|L], X, [Y|L1], L2) :-
  Y < X,
  partition(L, X, L1, L2).
partition([Y|L], X, L1, [Y|L2]) :-
  Y >= X,
  partition(L, X, L1, L2).

pos([], []).
pos([X|L1], [X|L2]) :-
  X > 0,
  !,
  pos(L1, L2).
pos([_|L1], L2) :-
  pos(L1, L2).

sum_list([], 0).
sum_list([X|L], S) :-
  sum_list(L, S1),
  S is X+S1.

ge_list([], _, []).
ge_list([X|Xr], Y, [X|Zs]) :-
  X >= Y,
  !,
  ge_list(Xr, Y, Zs).
ge_list([_|Xr], Y, Zs) :-
  ge_list(Xr, Y, Zs).

% vim: ft=prolog