Ruby vs Erlang building URL query params for a GET request

gistfile1.erl

-module(myjoin).

-export([join/1, join/2, start/0]).

start() ->
  join( [{foo,"bar"},{baz,"bang"}] ).

join([H|T]) ->
  {K,V} = H,
  Acc = atom_to_list(K) ++ "=" ++ V,
  join(T, Acc).

join([H|T], Acc) ->
  {K,V} = H,
  Addition = "&" ++ atom_to_list(K) ++ "=" ++ V,
  join(T, lists:append(Acc, Addition));

join([], Acc) ->
  error_logger:info_msg("Result ~p ~n", [Acc]).

% More concise variant
secondjoin([{Key,Value}|T], Separator) ->
  lists:flatten(
    Key ++ "=" ++ Value ++ [Separator ++ K ++ "=" ++ V || {K,V} <- T]
  ).

thirdjoin([{Key,Value}|T], Separator) ->
  lists:flatten(
    [Key, "=", Value, [[Separator, K, "=", V] || {K,V} <- T]]
  ).

;; this is teh common lisp
(format nil "{(A)=A^&~}" '(:foo bar :baz bla))

… I hope there is a more concise variant in erlang …