Happily, badarg fix is easily done. io:format/2
takes a list of terms as its the second argument. See:
(Erlang R15B02 (erts-5.9.2) [source] [64-bit] [smp:8:8] [async-threads:0] [hipe] [kernel-poll:false]
Eshell V5.9.2 (abort with ^G)
1> io:format("main ~p~n", 2).
** exception error: bad argument
in function io:format/3
called as io:format(<0.24.0>,"main ~p~n",2)
2> io:format("main ~p~n", [2]).
main 2
ok
Your second problem is that ?MODULE
just returns an atom of the current module's name. You'll want to send your message to a process. If you modify your code to look like so:
-module(case_).
-export([main/1, sender/2, receiver/0]).
main(Input) ->
io:format("main ~p~n", [Input]),
Recv = spawn(?MODULE, receiver, []),
case sender(Recv, Input) of
{Data} ->
io:format("Received ~p~n", [Data])
end.
sender(Pid, Input) ->
io:format("sender ~p~n", [Input]),
Ref = make_ref(),
Pid ! { self(), Ref, {send_data, Input}},
receive
{Ref, ok, Data} ->
{Data}
end.
receiver() ->
io:format("receiver ~n"),
receive
{Pid, Ref, {send_data, Input}} ->
Pid ! { Ref, ok, Input + Input}
end.
Then the interaction in the repl:
Erlang R15B02 (erts-5.9.2) [source] [64-bit] [smp:8:8] [async-threads:0] [hipe] [kernel-poll:false]
Eshell V5.9.2 (abort with ^G)
1> c("case_").
{ok,case_}
2> case_:main(2).
main 2
sender 2
receiver
Received 4
ok