Erlang: Shell not returning after spawn

Question

-module(core_profile).

-export([start/0]).

start() ->
    register(eProfile, spawn(loop())),
    ok.

loop() ->
    receive
            {Key, Pid} -> Pid ! getKey();
            {name, Pid} -> Pid ! getName();
            {address, Pid} -> Pid ! getAddress()
    end,
    loop().

This is my code

when I try to start the loop from the shell i get stuck.

2> Pid = spawn(fun()-> a end).     
<0.39.0>
3>c(core_profile.erl).
{ok, core_profile}
4>core_profile:start().

shouldn't the command return ok and then give me the next command line, instead of doing nothing?

Answer 1

When you do spawn(loop()) the loop function is called to evaluate a result (which will be passed on to spawn, so you enter the infinite loop.

Instead of calling the function you must pass the function reference by doing spawn(fun loop/0).

Answer 2

spawn(Fun) -> pid()

Types: Fun = function()

Returns the pid of a new process started by the application of Fun to the empty list [].

you should write register(eProfile, spawn( fun()-> loop() end)),