Upgrading to v0.6.x

cl-async has swapped out its backend library from libevent to libuv. For more information on why, see the related post.

The goal of the v0.6.x upgrade was to port cl-async over to libuv with the least amount of API changes as possible.

Library version

cl-async v0.6.x is built against libuv-1.0.0-rc2. This means you must use cl-async with libuv >= v1.0.0-rc2 or it will not work.


cl-async v0.6.x requires fast-io version de0e8b5 or greater, so be sure to pull fast-io from its aster branch if testing the non-quicklisp version of cl-async.

Breaking changes

Note that we’re only listing breaking changes here.

Base system

  • start-event-loop/with-event-loop no longer have fatal-cb or logger-cb keywords. Both features have been completely removed.


  • watch-fd is gone and has been replaced with pollers.


  • init-tcp-socket no longer takes an fd keyword. The concept of wrapping a cl-async socket around an existing fd no longer exists. Instead use the new poller object, which allows you to fire a callback whenever an fd can be read from/written to (although it does not provide an abstraction for writing to an fd which is no longer supported).
  • enable-socket/disable-socket are no longer implemented and will throw errors if used. libuv doesn’t have the concept of disabling reading/writing on a socket, and I’m not sure if this was ever that useful to begin with. If your app relies heavily on this feature, it can most likely be built back into cl-async (just open an issue).

Threading support

cl-async still has threading support, but it is now extremely simplified. Be sure to familiarize yourself with notifiers, which are the new threading abstraction.

  • enable-threading-support is gone and has no replacement. Threading support is always on now.
  • with-threading-context is gone and has no replacement. You can no longer add or change events to an event loop from another thread (but see notifiers).

Having trouble?

I may have missed some breaking changes or explained some things wrong. If you are having a problem getting your app running on cl-async v0.6.x, please let me know by opening a github issue and venting your frustrations. I’m here to help!