The singleton is the only logic opposite of multiplexing by data. Further it acts as simple interface within API. Therefore the most famous example would be the Factory Pattern. Advanced Gtk+ Sequencer implements the AgsRecallFactory in order to use with plugins. There exists an AgsTimestampFactory as well reserved for future use.
An other pattern in its infancy is the AgsAsyncQueue pattern a singleton, too. It should be responsible to caught up software based interrupts caused by its nature. Not a least is it needed to avoid crashes caused by assumptions of logical systems.
There's one big problem at the moment: Computing power. Recursive functions are believed to exhaust the stack. Further trees are generally recursive or have at least a depth. Timings to be used to tact a thread gives you an other dimension.
This is the reason, why interfering is programmatically given. But is the async queue pattern really a singleton or is polymorph by its nature? Where are the barriers of our mind and how much to you have to investigate abonden them.
Polymorph nature does it exist and could we make energy matrices the so called plasma?
It all requires an actor ...