Long-running Processes

Define a new module

To see how linking processes and trapping exits behave, we need processes that hang around long enough for us to observe them. IEx is a long-running process that is readily available, but we’ll need to spawn others for it to interact with.

To do that, let’s define a new module at lib/islands_engine/demo_proc.ex. All we need is a single function that implements an infinite recursion. We call it the loop/0 function. In the middle, we use receive/1 to retrieve the next message from the mailbox: