Transmutes signals into other signals, effectively a signal upgrade planner.
Providing the player with new tools or adjusting the game interface, without fundamentally changing gameplay.
Entities which interact with the circuit network.
Change blueprint behavior.
Would be nice to place the combinator within compact circiuts: https://mods.factorio.com/mod/compaktcircuit
yes, but unfortunately that is currently not possible due to the complicated nature of this compound entity, the mod has yet to be rewritten someday.