This is all very low-level stuff, though. Functional systems are high level abstractions typically erected on top of a low-level, imperative foundation. Let's

This is all very low-level stuff, though. Functional systems are high level abstractions typically erected on top of a low-level, imperative foundation. Let's use the particle effects example: One can describe how a particle system should behave using pure functions and immutable data whilst letting the actual simulation and rendering be handled by a low-level system that does all the dirty stuff necessary for speed.