Functional is a good way to 'specify' how a certain calculation/change has to be performed. When working with distributed systems with multiple actors making ch

Functional is a good way to 'specify' how a certain calculation/change has to be performed. When working with distributed systems with multiple actors making changes, you have to treat the whole system (distribute database) as a single value on which your functions operate. Then you can use the commutative properties of function to implement transactions. (If two operations on the system commute, they can be applied in either order on the system, to result in the same state.) But from such a specifying approach to a working system, is a long way.