無意味にマクロで。 macro_rules! fib { ( $n:expr ) => {{ let (mut x, mut y) = (1, 0); for _ in 0..$n { let tmp = box x; x += y; y = *tmp; } y }}; } fn main() { println!("{}", fib!(10)); } ( ՞ਊ ՞) :~/dev $ rustc --version # ちと古い rustc 1.…