package lwt

run p calls the Lwt scheduler repeatedly until p resolves, and returns the value of p if it is fulfilled. If p is rejected with an exception, that exception is raised.

Every native or bytecode program that uses Lwt should always use this function for evaluating a promise at the top level (such as its main function or main loop), otherwise promises that depend on I/O operations will not be resolved.

Example:

let main () = Lwt_io.write_line Lwt_io.stdout "hello world"

let () = Lwt_main.run @@ main ()

When targeting JavaScript, Lwt_main.run is not available, but neither it's necessary since the JS environment automatically takes care of the I/O considerations.

Note that you should avoid using run inside threads

• The calling threads will not resume before run returns.
• Successive invocations of run are serialized: an invocation of run will not terminate before all subsequent invocations are terminated.

Note also that it is not safe to call run in a function registered with Pervasives.at_exit, use the at_exit function of this module instead.

yield () is a threads which suspends itself and then resumes as soon as possible and terminates.

Functions that are called before the main iteration.

Functions that are called after the main iteration.

Sets of functions executed just before the program exit.

Notes:

• each hook is called exactly one time
• exceptions raised by hooks are ignored

at_exit hook adds hook at the left of exit_hooks