RPN calculator in Erlang

rpn.erl

-module(rpn).
-export([eval/2, op/1, is_op/1, start/0]).

%% I hope I never have to touch Erlang again

op("+") -> fun(L,R) -> L+R end;
op("*") -> fun(L,R) -> L*R end.

is_op(X) -> X == "+" orelse X == "*".

eval([], Stack) -> Stack;
eval([Num|Rest], Stack) when is_integer(Num) ->
  eval(Rest, [Num|Stack]);
eval([Cur|Rest], Stack) ->
  case is_op(Cur) of
  	true ->
  	  Rhs = hd(Stack),
      Lhs = hd(tl(Stack)),
      Res = apply(op(Cur), [Lhs, Rhs]),
      eval(Rest, [Res|tl(tl(Stack))])
  end.

start() ->
  Res = eval([3, 2, "+", 2, "*", 2, "*"], []),
  io:format("result: ~w~n", [Res]).