So you want to see all values in the todo_list part of the GenServer state (that’s different from “the value of todo_server”, as todo_server in your time_check function is the pid or name of a GenServer process).

Here is the code from your previous message:

def handle_call({:show_all}, _, {name, todo_list}) do
  {:reply, Todo.List.show_all(todo_list), {name, todo_list}}
end

You are matching on the message {:show_all}, so you need to issue the following call: GenServer.call(todo_server, {:show_all}).

Note that there are a couple of more things you could improve, not related to the main question though:

1. Your message is a tuple of a single element, {:show_all}. It’s not really necessary to wrap the message in a tuple, if it’s made of a single value: you could just send directly the atom :show_all instead. Of course, if you change this, the message that you send in GenServer.call should match the one that you pattern match in handle_call.

2. Instead of printing the list with IO.inspect, you could just return it, and in case let the caller print it.

As @lucaong pointed out, the message you send must have a matching function head. In this cas you are sending the message :show_all but you are only expecting a message {:show_all}. They are not the same.

For this class of error the messages are pretty clear I think so its good to get comfortable with reading function clause errors.