| 1 | -module(life). |
| 2 | |
| 3 | -export([bang/1]). |
| 4 | |
| 5 | |
| 6 | -define(CHAR_DEAD, 32). % " " |
| 7 | -define(CHAR_ALIVE, 111). % "o" |
| 8 | -define(INTERVAL, 100). |
| 9 | |
| 10 | |
| 11 | %% ============================================================================ |
| 12 | %% API |
| 13 | %% ============================================================================ |
| 14 | |
| 15 | bang(Args) -> |
| 16 | [X, Y] = [atom_to_integer(A) || A <- Args], |
| 17 | Board = init_board(X, Y), |
| 18 | life_loop(X, Y, Board). |
| 19 | |
| 20 | |
| 21 | %% ============================================================================ |
| 22 | %% Internal |
| 23 | %% ============================================================================ |
| 24 | |
| 25 | life_loop(X, Y, Board) -> |
| 26 | ok = do_print_board(Board), |
| 27 | timer:sleep(?INTERVAL), |
| 28 | life_loop(X, Y, next_generation(X, Y, Board)). |
| 29 | |
| 30 | |
| 31 | do_print_board(Board) -> |
| 32 | CharLists = array:to_list( |
| 33 | array:map( |
| 34 | fun(_, Row) -> |
| 35 | array:to_list( |
| 36 | array:map( |
| 37 | fun(_, State) -> |
| 38 | state_to_char(State) |
| 39 | end, |
| 40 | Row |
| 41 | ) |
| 42 | ) |
| 43 | end, |
| 44 | Board |
| 45 | ) |
| 46 | ), |
| 47 | |
| 48 | ok = lists:foreach( |
| 49 | fun(CharList) -> |
| 50 | ok = io:format("~s~n", [CharList]) |
| 51 | end, |
| 52 | CharLists |
| 53 | ). |
| 54 | |
| 55 | |
| 56 | state_to_char(0) -> ?CHAR_DEAD; |
| 57 | state_to_char(1) -> ?CHAR_ALIVE. |
| 58 | |
| 59 | |
| 60 | next_generation(W, H, Board) -> |
| 61 | array:map( |
| 62 | fun(Y, Row) -> |
| 63 | array:map( |
| 64 | fun(X, State) -> |
| 65 | Neighbors = filter_offsides(H, W, neighbors(X, Y)), |
| 66 | States = neighbor_states(Board, Neighbors), |
| 67 | LiveNeighbors = lists:sum(States), |
| 68 | new_state(State, LiveNeighbors) |
| 69 | end, |
| 70 | Row |
| 71 | ) |
| 72 | end, |
| 73 | Board |
| 74 | ). |
| 75 | |
| 76 | |
| 77 | new_state(1, LiveNeighbors) when LiveNeighbors < 2 -> 0; |
| 78 | new_state(1, LiveNeighbors) when LiveNeighbors < 4 -> 1; |
| 79 | new_state(1, LiveNeighbors) when LiveNeighbors > 3 -> 0; |
| 80 | new_state(0, LiveNeighbors) when LiveNeighbors =:= 3 -> 1; |
| 81 | new_state(State, _LiveNeighbors) -> State. |
| 82 | |
| 83 | |
| 84 | neighbor_states(Board, Neighbors) -> |
| 85 | [array:get(X, array:get(Y, Board)) || {X, Y} <- Neighbors]. |
| 86 | |
| 87 | |
| 88 | filter_offsides(H, W, Coordinates) -> |
| 89 | [{X, Y} || {X, Y} <- Coordinates, is_onside(X, Y, H, W)]. |
| 90 | |
| 91 | |
| 92 | is_onside(X, Y, H, W) when (X >= 0) and (Y >= 0) and (X < W) and (Y < H) -> true; |
| 93 | is_onside(_, _, _, _) -> false. |
| 94 | |
| 95 | |
| 96 | neighbors(X, Y) -> |
| 97 | [{X + OffX, Y + OffY} || {OffX, OffY} <- offsets()]. |
| 98 | |
| 99 | |
| 100 | offsets() -> |
| 101 | [offset(D) || D <- directions()]. |
| 102 | |
| 103 | |
| 104 | offset('N') -> { 0, -1}; |
| 105 | offset('NE') -> { 1, -1}; |
| 106 | offset('E') -> { 1, 0}; |
| 107 | offset('SE') -> { 1, 1}; |
| 108 | offset('S') -> { 0, 1}; |
| 109 | offset('SW') -> {-1, 1}; |
| 110 | offset('W') -> {-1, 0}; |
| 111 | offset('NW') -> {-1, -1}. |
| 112 | |
| 113 | |
| 114 | directions() -> |
| 115 | ['N', 'NE', 'E', 'SE', 'S', 'SW', 'W', 'NW']. |
| 116 | |
| 117 | |
| 118 | init_board(X, Y) -> |
| 119 | array:map(fun(_, _) -> init_row(X) end, array:new(Y)). |
| 120 | |
| 121 | |
| 122 | init_row(X) -> |
| 123 | array:map(fun(_, _) -> init_cell_state() end, array:new(X)). |
| 124 | |
| 125 | |
| 126 | init_cell_state() -> |
| 127 | crypto:rand_uniform(0, 2). |
| 128 | |
| 129 | |
| 130 | atom_to_integer(Atom) -> |
| 131 | list_to_integer(atom_to_list(Atom)). |