expose Suspend_ and its internal effect with an unstability alert

src/moonpool.ml

@@ -9,3 +9,4 @@ module Lock = Lock
 module Fork_join = Fork_join
 module Fut = Fut
 module Pool = Pool
+module Suspend_ = Suspend_

src/moonpool.mli

@@ -77,3 +77,13 @@ module Atomic = Atomic_
 
     This is either a shim using [ref], on pre-OCaml 5, or the
     standard [Atomic] module on OCaml 5. *)
+
+(** {2 Suspensions} *)
+
+module Suspend_ = Suspend_
+[@@alert unstable "this module is an implementation detail of moonpool for now"]
+(** Suspensions.
+
+    This is only going to work on OCaml 5.x.
+
+    {b NOTE}: this is not stable for now. *)

src/runner.ml

@@ -34,6 +34,4 @@ let run_wait_block self (f : unit -> 'a) : 'a =
 module For_runner_implementors = struct
   let create ~size ~num_tasks ~shutdown ~run_async () : t =
     { size; num_tasks; shutdown; run_async }
-
-  module Suspend_ = Suspend_
 end

src/runner.mli

@@ -64,13 +64,4 @@ module For_runner_implementors : sig
 
       {b NOTE}: the runner should support DLA and {!Suspend_} on OCaml 5.x,
       so that {!Fork_join} and other 5.x features work properly. *)
-
-  module Suspend_ = Suspend_
-  [@@alert
-    unstable "this module is an implementation detail of moonpool for now"]
-  (** Suspensions.
-
-      This is only going to work on OCaml 5.x.
-
-      {b NOTE}: this is not stable for now. *)
 end

src/suspend_.mli

@@ -32,6 +32,15 @@ type suspension_handler = {
 *)
 
 [@@@ifge 5.0]
+[@@@ocaml.alert "-unstable"]
+
+type _ Effect.t +=
+  | Suspend : suspension_handler -> unit Effect.t
+        (** The effect used to suspend the current thread and pass it, suspended,
+    to the handler. The handler will ensure that the suspension is resumed later
+    once some computation has been done. *)
+
+[@@@ocaml.alert "+unstable"]
 
 val suspend : suspension_handler -> unit
 (** [suspend h] jumps back to the nearest {!with_suspend}