It takes a little while to wrap your head around it -- I think it took me a solid 3 months before it clicked. Once it clicks though, the lifetime stuff is completely automatic. You really don't think about it. I think because Rust's syntax is so similar to what you might see in a C derived language it adds to the cognitive burden of learning lifetimes the first time around, but IMO, Rust should be the first thing people learn.

> long-running symbolic AI code

That sounds cool. An obvious question is, why not a lisp? But generally do you find f# works well on dotnet mixed with c#?

I love Lisp and Prolog the languages and I went there first -- the issue always turns out to be either (a) they make hard stuff really easy, but stuff that should be easy really hard, and (b) IMHO nothing even comes close to the .Net ecosystem when it comes to debugging tools, libs, etc. Clojure+Cursive comes closest, but the JVM world is a bit of a turn-off for me -- maybe I've been away from it too long, but it just seems a bit clunky. (And of course, reified generics, value types, etc., aren't available in the JVM.) The meta-programming story isn't as good as in Lisp/Prolog of course. JS (as others have said) an acceptable Lisp and has some advantages for the type of work I'm doing -- my problem with JS (and Typescript) isn't the language, but the run-time environment of Node, which makes things like true parallel programming a PITA and incurs serialization overhead between workers.

Thanks fort he reply. I've been looking at f# or ocaml for a symbolic code generation project, but haven't been able to decide.