To me it is about abstractions. FP cannot abstract over mutable state. In a way that is a good thing, less mutable state is easier to control as you grow a prog

To me it is about abstractions. FP cannot abstract over mutable state. In a way that is a good thing, less mutable state is easier to control as you grow a program. But inability to abstract is not a good thing. (Just like how async infects your callers, so does mutability in FP.) But also note that in this paper, the main trouble pointed out with imperative languages has long been solved. Using objects/classes and generics or runtime typed (dynamic) languages. All these make it easy to extend and compose.