康威生命游戏最简洁的序言实现是什么？

Question

今天晚上我推出了一个版本（如下所示），但感觉就像我从另一种程序语言移植而来，并没有利用许多“纯”Prolog 功能。

只需运行它，然后每次都按 Enter 键。

有一个版本（迷宫比例）Here

在使用 Prolog 解决问题时，我注意到的一件事是，总有（99% 的情况下）有一个更简洁的实现，感觉这次就是这种情况。

你能想到更好的实现吗？我对我的不满意。它有效，而且效率不是非常低（？），但仍然......

似乎我可以更好地利用统一，即。而不是将邻居视为相对于我单独检查的任何给定单元格的 X、Y 坐标，我本可以让 Prolog 为我做一些繁重的工作。

% Conway Game of Life (Stack Overflow, 'magus' implementation)

% The life grid, 15x15
grid([
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,1,0,1,0,1,0,0,0,0,0],
      [0,0,0,0,0,1,0,0,0,1,0,0,0,0,0],
      [0,0,0,0,0,1,0,0,0,1,0,0,0,0,0],
      [0,0,0,0,0,1,0,0,0,1,0,0,0,0,0],
      [0,0,0,0,0,1,0,1,0,1,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
     ]
   ).

% Infinite generates sep with keystroke
% -------------------------------------
life(Grid) :-
    dumpgen(Grid),
    onegen(Grid, 0, NewGrid),
    get_single_char(_),
    life(NewGrid).


% Dumps a generation out
% ----------------------
dumpgen([]) :- nl.
dumpgen([H|T]) :-
    write(H), nl,
    dumpgen(T).

% Does one generation
% --------------------------------
onegen(_, 15, []).

onegen(Grid, Row, [NewRow|NewGrid]) :-
    xformrow(Grid, Row, 0, NewRow),
    NRow is Row + 1,
    onegen(Grid, NRow, NewGrid).

% Transforms one row
% --------------------------------
xformrow(_, _, 15, []).
xformrow(Grid, Row, Col, [NewState|NewList]) :-
    xformstate(Grid, Row, Col, NewState),
    NewCol is Col + 1,
    xformrow(Grid, Row, NewCol, NewList).


% Request new state of any cell
% --------------------------------
xformstate(Grid, Row, Col, NS) :-
    cellstate(Grid, Row, Col, CS),
    nextstate(Grid, Row, Col, CS, NS).

% Calculate next state of any cell
% --------------------------------

% Cell is currently dead
nextstate(Grid, Row, Col, 0, NS) :-
    neightotal(Grid, Row, Col, Total),
    (Total =:= 3 -> NS = 1 ; NS = 0).

% Cell is currently alive
nextstate(Grid, Row, Col, 1, NS) :-
    neightotal(Grid, Row, Col, Total),
    ((Total =:= 2; Total =:=3)
    -> NS = 1; NS = 0).

% State of all surrounding neighbours
%-------------------------------------
neightotal(Grid, Row, Col, TotalSum) :-

    % Immediately neighbours X, Y
    XM1 is Col - 1,
    XP1 is Col + 1,
    YM1 is Row - 1,
    YP1 is Row + 1,

    % State at all those compass points
    cellstate(Grid, YM1, Col, N),
    cellstate(Grid, YM1, XP1, NE),
    cellstate(Grid, Row, XP1, E),
    cellstate(Grid, YP1, XP1, SE),
    cellstate(Grid, YP1, Col, S),
    cellstate(Grid, YP1, XM1, SW),
    cellstate(Grid, Row, XM1, W),
    cellstate(Grid, YM1, XM1, NW),

    % Add up the liveness
    TotalSum is N + NE + E + SE + S + SW + W + NW.


% State at any given row/col - 0 or 1
% -----------------------------------
% Valid range, return it's state
cellstate(Grid, Row, Col, State) :-
    between(0, 14, Row),
    between(0, 14, Col),
    nth0(Row, Grid, RL),
    nth0(Col, RL, State).

% Outside range is dead
cellstate(_, _, _, 0).

执行：

[debug]  ?- grid(X), life(X).
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,1,0,1,0,1,0,0,0,0,0]
[0,0,0,0,0,1,0,0,0,1,0,0,0,0,0]
[0,0,0,0,0,1,0,0,0,1,0,0,0,0,0]
[0,0,0,0,0,1,0,0,0,1,0,0,0,0,0]
[0,0,0,0,0,1,0,1,0,1,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]

[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,1,0,1,0,0,0,0,0,0]
[0,0,0,0,1,1,0,0,0,1,1,0,0,0,0]
[0,0,0,0,1,1,1,0,1,1,1,0,0,0,0]
[0,0,0,0,1,1,0,0,0,1,1,0,0,0,0]
[0,0,0,0,0,0,1,0,1,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]

[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,1,0,0,0,1,0,0,0,0,0]
[0,0,0,0,1,0,0,0,0,0,1,0,0,0,0]
[0,0,0,1,0,0,1,0,1,0,0,1,0,0,0]
[0,0,0,0,1,0,0,0,0,0,1,0,0,0,0]
[0,0,0,0,0,1,0,0,0,1,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]

etc.

Answer 1

我认为逻辑的简单性要求最简单的数据结构，并且最终类似于其他语言。

但试探性地，我们可以使用 SWI-Prolog 提供的无限精度整数和位域运算符：然后一行可以是整数，并且可以“一次”将 3 行移到一起来测试单元格的状态，并且屏蔽低位：我们只需要考虑 9 位，即 512 个值，可以预先计算。当然，边界检查可能会使算法复杂化：然后一些“带外”填充可能会有所帮助。

这应该很容易做到。

编辑：这是我的努力：

% Conway Game of Life (Stack Overflow, 'chac' implementation)
%

:- module(lifec, [play/0]).

play :-
    grid(G),
    lifec(G).

% The life grid, 15x15
grid([
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,1,0,1,0,1,0,0,0,0,0],
      [0,0,0,0,0,1,0,0,0,1,0,0,0,0,0],
      [0,0,0,0,0,1,0,0,0,1,0,0,0,0,0],
      [0,0,0,0,0,1,0,0,0,1,0,0,0,0,0],
      [0,0,0,0,0,1,0,1,0,1,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
      [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
     ]
   ).

% Infinite generates sep with keystroke
% -------------------------------------
lifec(Grid) :-
    make_ints(Grid, Ints, Size),
    lifei(Ints, Size).

lifei(Ints, Size) :-
    dumpgen(Ints, Size),
    onegen(Ints, Size, NewInts),
    get_single_char(_),
    !, lifei(NewInts, Size).

dumpgen(Ints, Size) :-
    forall(member(I, Ints),
           ( for_next(1, Size, _, show_bit(I)), nl) ).

onegen(Matrix, Size, NewMatrix) :-
    findall(NewBits,
        (three_rows(Matrix, Size, Rows),
         rowstate(Rows, 0, Size, 0, NewBits)), NewMatrix).

three_rows(Matrix, Size, Rows) :-
    nth1(I, Matrix, Row),
    ( I > 1 -> U is I - 1, nth1(U, Matrix, Up) ; Up = 0 ),
    ( I < Size -> D is I + 1, nth1(D, Matrix, Down) ; Down = 0 ),
    % padding: add 0 bit to rightmost position
    maplist(lshift, [Up, Row, Down], Rows).

:- dynamic evopatt/2.

rowstate([_, _, _], Size, Size, NewBits, NewBits) :- !.
rowstate([U, R, D], I, Size, Accum, Result) :-
    Key is (U /\ 7) \/ ((R /\ 7) << 3) \/ ((D /\ 7) << 6),
    evopatt(Key, Bit),
    Accum1 is Accum \/ (Bit << I),
    maplist(rshift, [U,R,D], P),
    J is I + 1,
    rowstate(P, J, Size, Accum1, Result).

%%  initialization
%
make_ints(Grid, Ints, Size) :-
    length(Grid, Size),
    maplist(set_bits(0, 0), Grid, Ints),
    % precompute evolution patterns
    retractall(evopatt(_, _)),
    for_next(0, 511, _, add_evopatt).

add_evopatt(N) :-
    maplist(take_bit(N), [0,1,2], U),
    maplist(take_bit(N), [3,4,5], V),
    maplist(take_bit(N), [6,7,8], Z),
    rule(U, V, Z, Bit),
    assert(evopatt(N, Bit)).

% rules from Rosetta Code
%
rule([A,B,C],[D,0,F],[G,H,I],1) :- A+B+C+D+F+G+H+I =:= 3.
rule([_,_,_],[_,0,_],[_,_,_],0).
rule([A,B,C],[D,1,F],[G,H,I],0) :- A+B+C+D+F+G+H+I < 2.
rule([A,B,C],[D,1,F],[G,H,I],1) :- A+B+C+D+F+G+H+I =:= 2.
rule([A,B,C],[D,1,F],[G,H,I],1) :- A+B+C+D+F+G+H+I =:= 3.
rule([A,B,C],[D,1,F],[G,H,I],0) :- A+B+C+D+F+G+H+I > 3.

%%  utilities
%
:- meta_predicate for_next(+,+,-,1).

for_next(From, To, N, Pred) :-
    forall(between(From, To, N), call(Pred, N)).

lshift(X, Y) :- Y is X << 1.
rshift(X, Y) :- Y is X >> 1.

show_bit(I, P) :-
    take_bit(I, P - 1, 1) -> put(0'*) ; put(0' ).

take_bit(N, Pos, Bit) :-
    Bit is (N >> Pos) /\ 1.

set_bits(_Index, Accum, [], Accum).
set_bits(Index, Accum, [ZeroOne|Rest], Number) :-
    Accum1 is Accum \/ (ZeroOne << Index),
    Index1 is Index + 1,
    set_bits(Index1, Accum1, Rest, Number).