> there is a real cost to having to manage object lifetimes in Rust.
I disagree. For the most part, you don't have to worry much about lifetimes in Rust once you have programmed in the language for a bit. It's a learning curve, like any other (functional languages have their own learning curve). There are cases now and then when you do have to think about it, but mostly it's either quickly fixing mistakes caught by the compiler (like any other type error, and this reduces as time goes by), or writing the correct code from the get-go.
That doesn't make Rust a better choice than the functional languages, but it certainly doesn't make it worse.
(of course, there are other reasons as to why Haskell/etc might be a better option for these people)
I disagree. For the most part, you don't have to worry much about lifetimes in Rust once you have programmed in the language for a bit. It's a learning curve, like any other (functional languages have their own learning curve). There are cases now and then when you do have to think about it, but mostly it's either quickly fixing mistakes caught by the compiler (like any other type error, and this reduces as time goes by), or writing the correct code from the get-go.
That doesn't make Rust a better choice than the functional languages, but it certainly doesn't make it worse.
(of course, there are other reasons as to why Haskell/etc might be a better option for these people)