Rust macro to format numbers into a given string. Numbers are are ascending accoriding to given tokens

format_numeric.rs

macro_rules! format_numeric {
    (($s: expr; $i: expr, $x: ident) -> ($($body:tt)*)) => {format!($s, $($body)* $i)};
    (($s: expr; $i: expr, $x: ident, $($y: ident),+) -> ($($body:tt)*)) => {format_numeric!(($s; $i + 1, $($y),+) -> ($($body)* $i,))};
    [$s: expr; $($y: ident),+] => { format_numeric!(($s; 1, $($y),+) -> ()) };
}

assert_eq!(
  format_numeric!["{}, {} and {}"; a, b, c],
  "1, 2 and 3"
)