I'm used to reading about a given C/C++ program being implemented in Rust, and was delighted to see such an effort in a functional programming language.

I know little about functional programming languages but I've always been interested in how languages like Ada and now Rust can help programmers write safer code. I'm curious what advantages a rewrite of a C/C++ app in a FP language provides and also what advantages a FP language brings in comparison to a language like Rust.