Rework APIs

[lpil]

Following on from gleam-lang/erlang#71

[karlsson]

Calls in gleam shell to sys:get_state / get_status for a given actor process works fine, but the observer tool (erlang) blocks these calls since in checks if attributes '$ancestors' and '$initial_call' exist. Adding those at actor init makes observer work as expected. I attach a patch.
observer_support.patch.txt

[karlsson]

Calls in gleam shell to sys:get_state / get_status for a given actor process works fine, but the observer tool (erlang) blocks these calls since in checks if attributes '$ancestors' and '$initial_call' exist. Adding those at actor init makes observer work as expected.

Actually calling erlang function proc_lib:spawn_link/1 instead of process.spawn will add the attributes to the process registry, so no need for any special function in that case. But maybe this shall be fixed later once 1.0 is out.

diff --git a/src/gleam/otp/actor.gleam b/src/gleam/otp/actor.gleam
index e732964..c8ae979 100644
--- a/src/gleam/otp/actor.gleam
+++ b/src/gleam/otp/actor.gleam
@@ -572,8 +572,7 @@ pub fn start(
   let ack_subject = process.new_subject()
   let self = process.self()
 
-  let child =
-    process.spawn(fn() { initialise_actor(builder, self, ack_subject) })
+  let child = spawn(fn() { initialise_actor(builder, self, ack_subject) })
 
   let monitor = process.monitor(child)
   let selector =
@@ -611,6 +610,9 @@ pub fn start(
   }
 }
 
+@external(erlang, "proc_lib", "spawn_link")
+fn spawn(start_fun: fn() -> ExitReason) -> Pid
+
 /// Send a message over a given channel.
 ///
 /// This is a re-export of `process.send`, for the sake of convenience.

[lpil]

@karlsson Yes for sure! I was just talking about this with the team.

Replicating the special process functionality was great for proving out the gleam_erlang design and ensuring it was capable enough to implement things this complex, but I think there's a lot to gain now by using higher level Erlang building blocks, specifically proc_lib. Better compatibility as you say, and also we won't get caught up by interface changes, such as the addition of aliases.

[karlsson]

Applying this:

diff --git a/src/gleam_otp_external.erl b/src/gleam_otp_external.erl
index 13d0546..bf733e7 100644
--- a/src/gleam_otp_external.erl
+++ b/src/gleam_otp_external.erl
@@ -43,12 +43,17 @@ convert_system_message({system, {From, Ref}, Request}) when is_pid(From) ->
     end.
 
 process_status({status_info, Module, Parent, Mode, DebugState, State}) ->
-    Data = [
-        get(), Mode, Parent, DebugState,
-        [{header, "Status for Gleam process " ++ pid_to_list(self())},
-         {data, [{'Status', Mode}, {'Parent', Parent}, {'State', State}]}]
-    ],
-    {status, self(), {module, Module}, Data}.
+     Data = [
+         get(), Mode, Parent, DebugState,
+         [{header, "Status for Gleam process " ++ pid_to_list(self())},
+           {data, [
+             {"Gleam behaviour", Module},
+             {"Status", Mode},
+             {"Parent", Parent}]},
+          {data, [{"State", State}]}
+         ]
+     ],
+     {status, self(), {module, Module}, Data}.
 
 application_stopped() ->
     ok.

Will give you this:

instead of this:

Note that you get a Gleam behavior!

[lpil]

Love it @karlsson ! Would you like to make a pull request?