Channel Synchronization in OCaml

This example demonstrates how to use channels for synchronization between threads in OCaml. While OCaml doesn’t have built-in goroutines, we can use threads and channels to achieve similar functionality.

open Unix

(* This is the function we'll run in a separate thread. The
   'done_' channel will be used to notify another thread
   that this function's work is done. *)
let worker done_ =
  print_string "working...";
  Unix.sleep 1;
  print_endline "done";
  (* Send a value to notify that we're done. *)
  Event.sync (Event.send done_ true)

let main () =
  (* Create a channel to notify on. *)
  let done_ = Event.new_channel () in
  (* Start a worker thread, giving it the channel to notify on. *)
  let _ = Thread.create worker done_ in
  (* Block until we receive a notification from the worker on the channel. *)
  let _ = Event.sync (Event.receive done_) in
  ()

let _ = main ()

To run this program:

$ ocamlc -thread unix.cma threads.cma example.ml -o example
$ ./example
working...done

In this OCaml version:

1. We use the Unix module for the sleep function and the Thread module for creating threads.

2. Instead of Go’s channels, we use OCaml’s Event module, which provides a way to synchronize between threads.

3. The worker function is similar to the Go version, but it uses Event.send to signal completion.

4. In the main function, we create a channel using Event.new_channel (), start a new thread with Thread.create, and then wait for the notification using Event.receive.

5. The Event.sync function is used to perform synchronous operations on events.

If you removed the Event.sync (Event.receive done_) line from this program, the program would exit before the worker even started, similar to the Go version.

Note that while this example demonstrates thread synchronization in OCaml, for more complex scenarios, you might want to consider using higher-level concurrency libraries like Lwt or Async, which provide more sophisticated tools for managing concurrent operations in OCaml.