Prolog de Kakeibo

accounts.pl

% it is fiction!!
accounts(給料, 200000).
accounts(家賃, 60000).
accounts(借金, 10000).
% vim: set syntax=prolog:

category.pl

income(給料).
expense(家賃).
expense(借金).

main.pl

#!swipl -q -g main -s

:- use_module(library(apply)).
:- use_module(library(lists)).
:- include(category).
:- include(accounts).
:- include(tools).

main :-
    print('
==================================
Logical Kakeibo
==================================
\n'),
    account_list(INCOMES, EXPENSES),
    costs(INCOMES, INCOME),
    costs(EXPENSES, EXPENSE),
    format("収入 ~f円\n", INCOME),
    format("出費 ~f円\n", EXPENSE),
    format("残り ~f円\n", INCOME - EXPENSE),
    halt.
% vim: set syntax=prolog:

tools.pl

isincome((KIND, _)) :- income(KIND).
getcost((_, COST), COST).
costs(ACCOUNTLIST, COST) :- 
    maplist(getcost, ACCOUNTLIST, COSTS),
    sumlist(COSTS, COST).

account_list(INCOMES, EXPENSES) :-
    findall((X, Y), accounts(X, Y), ACCOUNTS),
    partition(isincome, ACCOUNTS, INCOMES, EXPENSES).