111 lines
2.4 KiB
Prolog
111 lines
2.4 KiB
Prolog
:- module(between, [between/3, gen_int/1, gen_nat/1, numlist/2, numlist/3, repeat/1]).
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%% TODO: numlist/5.
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:- use_module(library(lists), [length/2]).
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:- use_module(library(error)).
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between(Lower, Upper, X) :-
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must_be(integer, Lower),
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must_be(integer, Upper),
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can_be(integer, X),
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( nonvar(X) ->
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Lower =< X,
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X =< Upper
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; Lower =< Upper,
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between_(Lower, Upper, X)
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).
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between_(Lower, Lower, Lower) :- !.
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between_(Lower, Upper, Lower1) :-
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( Lower < Upper,
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( Lower1 = Lower
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; Lower0 is Lower + 1,
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between_(Lower0, Upper, Lower1)
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)
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).
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enumerate_nats(I, I).
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enumerate_nats(I0, N) :-
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I1 is I0 + 1,
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enumerate_nats(I1, N).
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gen_nat(N) :-
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can_be(integer, N),
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( var(N) -> enumerate_nats(0, N)
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; true
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).
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enumerate_ints(I, I).
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enumerate_ints(I0, N) :-
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I0 > 0,
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N is -I0.
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enumerate_ints(I0, N) :-
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I1 is I0 + 1,
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enumerate_ints(I1, N).
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gen_int(N) :-
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can_be(integer, N),
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( var(N) -> enumerate_ints(0, N)
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; true
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).
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repeat_integer(N) :-
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N > 0.
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repeat_integer(N0) :-
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N0 > 0, N1 is N0 - 1, repeat_integer(N1).
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repeat(N) :-
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must_be(integer, N), repeat_integer(N).
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numlist(Upper, List) :-
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( integer(Upper) -> findall(X, between(1, Upper, X), List)
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; List = [_|_], length(List, Upper), findall(X, between(1, Upper, X), List)
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).
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diag_nats(M, N, M, N).
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diag_nats(M, 0, M1, N1) :-
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!,
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M0 is M+1,
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diag_nats(0, M0, M1, N1).
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diag_nats(M, N, M1, N1) :-
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M0 is M+1,
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N0 is N-1,
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diag_nats(M0, N0, M1, N1).
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diag_nats(0, 0).
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diag_nats(M, N) :-
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diag_nats(0, 1, M, N).
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diag_nats_signs(0, 0, 0, 0) :- !.
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diag_nats_signs(0, M, 0, M0) :- !,
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( M0 = M ; M0 is -M ).
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diag_nats_signs(M, 0, M0, 0) :- !,
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( M0 = M ; M0 is -M ).
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diag_nats_signs(M, N, M, N).
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diag_nats_signs(M, N, M, N0) :-
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N0 is -N.
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diag_nats_signs(M, N, M0, N) :-
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M0 is -M.
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diag_nats_signs(M, N, M0, N0) :-
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M0 is -M, N0 is -N.
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diag_ints(M, N, M0, N0) :-
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diag_nats(M, N),
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diag_nats_signs(M, N, M0, N0).
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diag_ints(M, N) :-
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diag_ints(_, _, M, N).
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gen_ints(L, U) :-
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can_be(integer, L), can_be(integer, U),
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( integer(L), integer(U), !
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; integer(L) -> gen_int(U)
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; integer(U) -> gen_int(L)
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; diag_ints(L, U)
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),
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L =< U.
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numlist(Lower, Upper, List) :-
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gen_ints(Lower, Upper), findall(X, between(Lower, Upper, X), List).
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