+ val react : t -> states:int list -> t
+end
+
+
+module Conway : CELL = struct
+ type t = D | A
+
+ let of_int = function
+ | 0 -> D
+ | 1 -> A
+ | _ -> assert false
+
+ let to_int = function
+ | D -> 0
+ | A -> 1
+
+ let to_string = function
+ | D -> " "
+ | A -> "o"
+
+ let create () =
+ Random.int 2 |> of_int
+
+ let state = to_int
+
+ let react t ~states =
+ let live_neighbors = List.fold_left states ~init:0 ~f:(+) in
+ match t with
+ | A when live_neighbors < 2 -> D
+ | A when live_neighbors < 4 -> A
+ | A when live_neighbors > 3 -> D
+ | D when live_neighbors = 3 -> A
+ | A -> A
+ | D -> D
+end
+
+
+module Automaton : sig
+ type t
+
+ val create : rows:int -> columns:int -> interval:float -> t
+
+ val loop : t -> unit
+end = struct
+ type t = { grid : Conway.t Matrix.t
+ ; interval : Time.Span.t
+ ; bar : string
+ }
+
+ let create ~rows:rs ~columns:ks ~interval =
+ { grid = Matrix.map ~f:Conway.create (Matrix.create ~rs ~ks ())
+ ; interval = Time.Span.of_float interval
+ ; bar = String.make ks '-'
+ }
+
+ let print t =
+ print_endline t.bar;
+ Matrix.print t.grid ~to_string:Conway.to_string;
+ print_endline t.bar
+
+ let next t =
+ let grid =
+ Matrix.mapi t.grid ~f:(
+ fun point cell ->
+ let neighbors = Matrix.get_neighbors t.grid point in
+ Conway.react cell ~states:(List.map neighbors ~f:Conway.state)
+ )
+ in
+ {t with grid}
+
+ let rec loop t =
+ print t;
+ Time.pause t.interval;
+ loop (next t)