How to schedule a task in OCaml?

问题

I have a task need to be done every 4 hours or once a day.

In Java, it has quartz or spring or timer.

But in OCaml, how do I do that? Any good lib for that?

回答1:

I don't know any library to do that, but I think you can easily implement that kind of behavior using the Lwt library.

Little example, to print Hello world every 4 hours :

let rec hello () = 
    Lwt.bind (Lwt_unix.sleep 14400.) 
       (fun () -> print_endline "Hello, world !"; hello ())
Lwt.async (hello)

The Lwt.async function call the function given (here, hello) in an asynchronous light weight thread, so you're free to do other stuff in your program. As long as your program doesn't exit, "Hello world" will be printed every 4 hours.

If you want to be able to stop it, you can also launch the thread like this instead of Lwt.async :

let a = hello ()

And then, to stop the thread :

Lwt.cancel a

Be aware that Lwt.cancel throws a "Lwt.canceled" exception !

Then, to be able to launch a task at a particular time of day, I can only encourage you to use functions from the Unix module, like localtime and mktime.

来源：https://stackoverflow.com/questions/17091116/how-to-schedule-a-task-in-ocaml