Command line parameter for specifying ALSA output device. regular beat sent by 'streamed' results in irregular sound check whether this also happens in offline rendering (no) check whether this also can be seen in recorded wave file check whether this also happens with our eventlist based synthesizer Has this to do with re-timestamping that I activated in ALSA? The problem is the following: If there is a buffer under-run the incoming events come too late and thus occur only in the later part of the each block. The Echo events come back immediately but due to restamping with the timestamp of the current time. That is too late, and thus too many events are fetched and their time is limited to the end of each block. Current approach: Do not restamp Echo events. With Ctrl-Z + fg we can halt the synthesizer and thus we can simulate the reaction of the system to high load. AllSoundOff should remove all sub-processes from the queue Causal.Process.mapMaybe, catMaybes, initWith, MIDIControllerSet.getSlice should merge chunks that are separated by empty lists. This way we remove duplicate nodes in piecewise constant signals, and thus speedup following fmaps. Type class for streams, that allow for merging of time differences Type class for arrows, that support a state Wrapper: Events a = EventList [a] make traverse deeply strict against Map, in order to prevent space leak dangerous, because in general state might a lazy list, that shall be deconstructed lazily