The Paradigms of Swift

Rob Napier on why Swift is not a functional language:

Swift is a multi-paradigm, but it’s not OOP/functional. It’s OOP/generic. Generic programming is primarily concerned with general purpose algorithms that can be applied to arbitrary types. It has some similarities with functional programming, and there are certainly languages that are both functional and generic, but generic programming doesn’t care if the algorithms are functions (things that take and return immutable values) or processes (things that mutate state).