[mightybyte]

The term "functional programming" is so ill-defined as to be effectively useless in any kind of serious conversation. I'm not aware of any broadly accepted consensus definition. Sometimes people want to use this category to talk about purity and control of side effects and use the term "functional programming" to refer to that. I would advocate the more targeted term "pure functional programming" for that definition. But in general I try to avoid the term altogether, and instead talk about specific language features / capabilities.

[jghn]

> The term "functional programming" is so ill-defined as to be effectively useless in any kind of serious conversation.

This is important. I threw my hands up and gave up during the height of the Haskell craze. You'd see people here saying things like LISP wasn't real FP because it didn't match their Haskell-colored expectations. Meanwhile for decades LISP was *the* canonical example of FP.

Similar to you, now I talk about specific patterns and concepts instead of calling a language functional. Also, as so many of these patterns & concepts have found their way into mainstream languages now, that becomes even more useful.

[Iceland_jack]

To your point, but lispers like the author of Let Over Lambda specifically called Lisp non-functional.

[agumonkey]

to add a grain of salt, some of the lisp world is not functional, a lot of code is straight up imperative / destructive. but then yeah a lot of the lisp culture tended to applicative idioms and function oriented, even without the static explicit generic type system of haskell.

[submain]

I usually define functional programming as "how far away a language is from untyped lambda calculus". By that definition, different languages would fall in different parts of that spectrum.