Module Lwt: cooperative light-weight threads.

Module Lwt_unix: thread-compatible system calls

Module Lwt_chan: cooperative, Pervasives-like, I/O functions

Are we using an SSL socket?

Concurrency

Cooperative getaddrinfo with cache (using Lwt_preemptive.detach)

set the default handler for exception occurring after a timeout.

This module allows to mix preemptive threads with Lwt cooperative threads.