freq.erl

-module(freq).
-export([main/0]).

freq(B) when is_binary(B) ->
  Arr = array:new([{size,256}, {fixed,true}, {default,0}]),
  freq(B, Arr).

freq(<<>>, Arr) -> Arr;
freq(<<B:8,Rest/binary>>, Arr) ->
  Old = array:get(B, Arr),
  New = array:set(B, Old+1, Arr),
  freq(Rest, New).

main() ->
  F = freq(<<"abcdefabc">>),
  io:format("~p~n", [array:to_list(F)]).