1. More generally I'd say it's "minimise mutable state". 2. Almost all programs are necessarily stateful, but most of the code within them does not have to be.

1. More generally I'd say it's "minimise mutable state". 2. Almost all programs are necessarily stateful, but most of the code within them does not have to be. As such, all FP languages support working with state, e.g. Scala which is essentially just Java with more powerful types and easier creation of immutable values and lambdas, so you can program with state as easily as you can in Java. And Haskell, which separates stateful functions by type, so that the programmer and the compiler know which functions have state and which do not.