Erlang fib

-module(fib).
-export([fib/1, fib2/1, start/0, server/1]).

fib(1) -> 1;

fib(2) -> 1;

fib(N) ->
    fib(N-1) + fib(N-2).

fib2(N) ->
    fib_server ! {N, self()},
    receive
 {ok, Value} ->
     Value;
 _ ->
     Result = fib2(N - 1) + fib2(N - 2),
     fib_server ! {add, N, Result},
     Result
    end.

server(Dict) ->
    receive
 {N, Client} ->
     case dict:find(N, Dict) of
  {ok, Value} ->
      Client ! {ok, Value},
      fib:server(Dict);
  _ -> Client ! nil,
       fib:server(Dict)
     end;
 {add, N, Result} ->
     fib:server(dict:store(N, Result, Dict));
 dump -> io:format("~p~n", [Dict]),
  fib:server(Dict)
    end.

start() ->
    Dict = dict:new(),
    Dict1 = dict:store(1, 1, Dict),
    Dict2 = dict:store(2, 1, Dict1),
    Pid = spawn(fib, server, [Dict2]),
    register(fib_server, Pid).