[_Robbie]

I will discuss Haskell, since I am not very familiar with other FP languages. In Haskell static typing is more useful than in other languages. This is because in Haskell the type signature of a function gives an upper bound of what the function does. In an impure language, a function may change any accessible mutable values and/or perform IO. These possible side effects mean that in an impure language the type of a function is a very weak indicator of what the function actually does.

[vram22]

So you're saying that static typing helps FP and hence is sort of a part of it?

Thanks for the answer.