1#[macro_export] 2macro_rules! arr { 3 ($producer:expr) => { 4 core::array::from_fn($producer) 5 }; 6 ($producer:expr; $N:literal) => { 7 core::array::from_fn::<_,$N,_>($producer) 8 }; 9 ($($val:expr),+) => { 10 [$($val),+] 11 } 12}