S-expression in Rust macro

macro.lisp.rs

macro_rules! plus {
    () => {0};
    ($car:expr $(, $cdr:expr)*) => { $car + plus!($($cdr),*) };
}

macro_rules! mul {
    () => {1};
    ($car:expr $(, $cdr:expr)*) => {$car * mul!($($cdr),*)};
}

macro_rules! eval {
    ( [ $($e:tt)* ] ) => { eval!( $($e)* ) };
    (+ $($e:tt)*) => {
        plus!($( eval!($e) ),*)
    };
    (* $($e:tt)*) => {
        mul!($( eval!($e) ),*)
    };
    ($e:expr) => { $e };
}

fn main() {
    let x = eval![* 1 2 [+ 1 2] [*]];
    println!("{}", x);
}

rustc -Z unstable-options --pretty expanded macro.lisp.rs