Rust does not "forbid shared mutable state". Instead it offers both the usual usual shared references along with a new unique reference, but restricts shared references so the type being pointed to must opt into aliased mutation. Making sharing and aliased mutation explicit in the type system allows both the programmer and the compiler to reason about which variables can change behind your back when calling functions or mutating through other pointers, and which ones are referentially transparent. (Though this property does come with sacrifices to programmer convenience, namely the restrictions on Cell, the runtime overhead and panic-proneness of RefCell, and the unsafe blocks associated with UnsafeCell. Hopefully GhostCell can do better.)
Also, the article explicitly says that the rust compiler is usually right, with - IMO - the implication that haskell is likely usually right for its purposes too.
But people have to get mad about the one throwaway comment at the top without even reading the next paragraph, let alone the rest of the article :(
Probably good feedback for the author. People don't have time to read every article they come across fully so they're evaluating quality as they go. Throwaway comments like this will have the effect of losing audience so best to leave them out.
