“Nondeterminism = parallel processing + shared state”~ Martin Odersky (Scala designer)
But some things are inherently nondeterministic. Things like the timing of user input and network I/O. So how can we ever know if our code really works? Easy: Isolation.
… its speedy performance. But there is also an equally important — if not more important — property. The concept makes it possible to represent the UI as a function of its state.