I don't understand the basis for the grandparent comment, that is, why is the use of rust such a surprise? I only use dynamic scripting languages (so I can't speak from experience) but from what I understand rust is a great language; extremely fast and easier/safer to work with than c++. Why wouldn't it be a good choice for OP's CLI?
I've been mostly doing Haskell for last 9 years, but I find Rust to be awesome nowadays. Great feedback from the type checker, no unnecessary runtime, great tooling. It's unique in a sense that it's fast, but quite safe at the same type. If it would have Higher-Kinded Types, it would be even better for me personally, but it's a tricky compromise from a compiler design perspective.
Also, I find static linking to work great with Rust, so it's quite easy to distribute your app.
