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@seancribbs
Forked from jszmajda/Readme.md
Last active September 7, 2021 17:51
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Game of Life in Erlang

Conway's Game of Life in Erlang, in 2 hours, with 0 Erlang experience, in 20 lines of code.

1337 h4x0rs:

  • @jszmajda
  • @ngauthier
  • @ericoestrich
  • @danivovich
  • @kafuchau

Later refactored and enhanced by @seancribbs

-module(gol).
-export([transmute_world/1, display/1, run/2]).
lives(2,true) ->
true;
lives(3,_) ->
true;
lives(_,_) ->
false.
%% neighbors1(Xin,Yin, World) ->
%% length([
%% true || {X, Y, true} <- World,
%% X >= Xin - 1, X <= Xin + 1,
%% Y >= Yin - 1, Y <= Yin + 1,
%% not (X == Xin andalso Y == Yin)
%% ]).
neighbors2(Xin, Yin, World) ->
Neighbors = [ {Xin + X, Yin + Y} ||
X <- [-1, 0, 1],
Y <- [-1, 0, 1],
not (X == 0 andalso Y == 0)],
length([ true || {X, Y} <- Neighbors,
{XW, YW, true} <- World,
X == XW andalso Y == YW]).
transmute_world(World) ->
[ {X, Y, lives(neighbors2(X,Y, World), Alive)} || {X,Y,Alive} <- World ].
sort_by_rows({_, Y0, _}, {_, Y1, _}) when Y0 < Y1 ->
true;
sort_by_rows({X0, Y, _}, {X1, Y, _}) when X0 < X1 ->
true;
sort_by_rows(_, _) -> false.
cell_to_display_fold({_X, Y, Alive}, {Row, Output}) ->
Char = case Alive of
true -> $X;
false -> $.
end,
case Row of
Y -> {Row, [Char|Output]};
_ -> {Y, [Char, $\n| Output]}
end.
display(World) ->
%% sort by Y so we get rows together
World1 = lists:sort(fun sort_by_rows/2, World),
%% Turn the true/false into strings for output, adding line returns after rows
{_Row, Output} = lists:foldl(fun cell_to_display_fold/2, {0, []}, World1),
%% Clear the screen and print the board at the top left.
io:format("\e[2J\e[0;0H~ts~n", [lists:reverse(Output)]).
run(World, None) when None =< 0 ->
World;
run(World, Iters) ->
display(World),
timer:sleep(500),
run(transmute_world(World), Iters - 1).
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