Module Effect_sequencerSource

A sequencer for ensuring that the current effect completes before the next one starts.

Makes a new sequencer.

Produces an effect that first waits in line until all the effects in front of it are finished running, and then runs the provided effect.

A couple points of emphasis:

• Like the provided effect, using the resulting effect multiple times will do the side-effect multiple times (unlike _ Deferred.t).
• The effect starts waiting in line _when the effect runs_, rather than when run is called. Consequently, using the effect multiple times means that each run of the effect will be waiting in line individually, rather than all of them sharing a spot in line.

Based on these points, you can think of run as a function that returns the an effect that is almost exactly like the effect it was given, but "more atomic", in that it won't get interleaved with other effects sent through the same sequencer.

WARNING: It's very easy to "deadlock" with this function. Just call run within the effect that you pass to run, using the same sequencer for both. The result is that the returned function will never complete. (although, it's worth noting, the rest of your program won't be blocked from running).