I'm not sure I see what having "a strong type system" has to do with whether or not a language can be considered functional. It seems like it's just a way to s

I'm not sure I see what having "a strong type system" has to do with whether or not a language can be considered functional. It seems like it's just a way to say that Haskell and the MLs are the only languages that qualify. And that sounds more like PR than a formal definition. It's also not really historically accurate. People were referring to languages based on the untyped lambda calculus as "functional" before things like Hindley-Milner appeared (in the 70s). Were they (and I'm talking about PL researchers) all speaking incorrectly?