Birthday fun in Erlang

birthday.erl

% Usage:
% $ erl
% > c(birthday).
% > Pid = birthday:start().
% > birthday:greet(Pid, "Waschti").
-module(birthday).
-export([start/0, greet/2]).

birthday(Greets) ->
    receive
        {greet, Name, Pid} ->
            [Next|Rest] = Greets,
            Greet = lists:flatten(io_lib:format(Next, [Name])),
            Pid ! {greeting, Greet},
            birthday(lists:append(Rest, [Next]));
        _Else ->
             exit(nope)
    end.

greet(Pid, Name) ->
    Pid ! {greet, Name, self()},
    receive
        {greeting, Greet} ->
            Greet
    end.

start() ->
    Greetings = [ "Herzlichen Glückwunsch zum Geburtstag, ~s!"
                , "Alles, alles Gute zu deinem Geburtstag, ~s!"
                , "Happy Birthday to youu, Happy birthday to youu ~s!"
                ],
    spawn(fun() -> birthday(Greetings) end).