use std::{fmt, fmt::Display}; struct Wrap(T); impl Display for Wrap> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { for (ix, r) in self.0.iter().enumerate() { if ix > 0 { write!(f, " ")?; } r.fmt(f)?; } Ok(()) } } #[argio::argio(output = Wrap)] fn main(n: usize) -> Vec { (0..n).map(|i| i * 2).collect() }