Interesting, my lack of real experience in Scheme will make this take a bit more work for me to fully work through the implications of. It's not immediately clear to what this would mean for Rust, since there is already a loop construct (well, three of them, although two of them are syntactic sugar for the first). You could define a macro around it in Rust today, but it would be fairly uninteresting: https://play.rust-lang.org/?version=stable&mode=debug&editio...
Yes, I agree. Like I said, it might be useful when dealing with something that is easier to express in (tail) recursion form instead of an iteration.
Anyway, here's something more-or-less equivalent in Rust, which will blow the stack if made to loop too many times: https://play.rust-lang.org/?version=stable&mode=debug&editio...
(There may be a way to use a closure instead of a function to avoid hard-coding the type of `$i` in the macro, but I can't find an easy way to write a recursive closure call in Rust).