IMO Rust is what you'd get if you took a functional lang designer and forced them at gunpoint to create a procedural systems lang. It's not functional, but you can tell it was largely inspired by ideas from the paradigm -- immutable by default, expression-centric to an extent, features like Option<T> and Result<T> available, etc.

It's certainly a language that encourages programming in a functional flavor, even if the lang itself isn't functional.