When you do fully value-oriented programming in Rust (i.e. no interior mutability involved) that's essentially functional programming. There's mutable, ephemeral data involved, but it's always confined to a single well-defined context and never escapes from it. You can even have most of your code base be sans-IO, which is the exact same pattern you'd use in Haskell.

I actually like rust more than Haskell, but `You can even have most of your code base be sans-IO, which is the exact same pattern you'd use in Haskell.` glosses over the fact that in Haskell it's enforced at compile time.