#![feature(trace_macros)]
#![feature(macro_literal_matcher)]

//trace_macros!(true);

macro_rules! lisp{
    {(define $a:tt $b:tt)} => {let lisp!($a) = lisp!($b)};
    {(begin $($a:tt)*)} => {{$(lisp!{$a});*}};
    {(lambda ($($a:tt)*) $b:tt)} => {(|$($a),*|lisp!{$b})};
    {(($($a:tt)*) $($b:tt)*)} => {lisp!{($($a)*)}($(lisp!{$b}),*)};
    {($a:tt $($b:tt)*)} => {lisp!($a)($(lisp!{$b}),*)};
    {$a:literal} => {$a};
    {$a:ident} => {$a};
}

fn plus(x:i32,y:i32) -> i32 {
    println!("{}+{}={}",x,y,x+y);
    x+y
}

fn main() {
    println!("{}",lisp!{
        (begin
            (define plus3
                (lambda (x y z)
                    (plus x (plus y z))))
            (define a 1)
            (define b (plus a 2))
            (define c (plus3 a b 3))
            (plus3 (plus a b) (plus b c) (plus c a)))
    });
}