ML has always had easy mutables in the form of references, and the closest deployed language to Standard ML (Ocaml and Reason), has always had for-loops and whi

ML has always had easy mutables in the form of references, and the closest deployed language to Standard ML (Ocaml and Reason), has always had for-loops and while-loops. Mutable references are used frequently. Rust is great because it's low level, high-performance, non-garbage collected and it's primary inspiration for higher-level programming is languages like ML and Haskell.