beersong.erl

-module(beersong).
-export([sing/0]).

-define(LIMIT, 99).
-define(TEMPLATE_0, "~s of beer on the wall, ~s of beer.~nGo to the store and buy some more, 99 bottles of beer on the wall.~n").
-define(TEMPLATE_N, "~s of beer on the wall, ~s of beer.~nTake one down and pass it around, ~s of beer on the wall.~n~n").

print_verse(0)      -> io:format(?TEMPLATE_0, phrase(0));
print_verse(Bottle) -> io:format(?TEMPLATE_N, phrase(Bottle)).
 
phrase(0)      -> ["No more bottles", "no more bottles"];
phrase(1)      -> ["1 bottle", "1 bottle", "no more bottles"];
phrase(2)      -> ["2 bottles", "2 bottles", "1 bottle"];
phrase(Bottle) -> lists:duplicate(2, integer_to_list(Bottle) ++ " bottles") ++
                  [integer_to_list(Bottle-1) ++ " bottles"].

sing() -> lists:foreach(fun print_verse/1, lists:seq(?LIMIT,0,-1)).