Compare rust head to head with Haskell and and it will come out of that fight sporting some serious bruises. But Rust's lifetimes are a genuinely interesting idea that you see nowhere else when people start discussing sophisticated type systems
... is this what you mean?
I revere Harper, but his anti-Haskell rants just seem unhinged to me.
I've heard bad things about Harper, but then he's an accomplished fellow, which doesn't mean he has to be nice. I only expect him to be truthful, is all. Maybe he's just ML's LISP zealot like the now deceased Dane whose name I forgot.