Top layer is for "frontend", whatever that means for the product (UI, sound, simulation, etc.), the stuff with side effects. "Systems".
Middle layer is purely functional, for business/domain logic AKA utility functions. The most liquid layer, but should not be confused as trivial.
Bottom layer is where state (or a way to access & modify it) lives. Data access layer, component layer, etc.
Top layer is for "frontend", whatever that means for the product (UI, sound, simulation, etc.), the stuff with side effects. "Systems".
Middle layer is purely functional, for business/domain logic AKA utility functions. The most liquid layer, but should not be confused as trivial.
Bottom layer is where state (or a way to access & modify it) lives. Data access layer, component layer, etc.