#![feature(unboxed_closures)]
#![feature(fn_traits)]

struct Adder;

impl FnOnce<(i32, i32)> for Adder {
    type Output = i32;
    extern "rust-call" fn call_once(self, args: (i32, i32)) -> i32 {
      args.0 + args.1
    }
}

impl FnOnce<(f32, f32)> for Adder {
    type Output = f32;
    extern "rust-call" fn call_once(self, args: (f32, f32)) -> f32 {
      args.0 + args.1
    }
}

impl FnOnce<(f64, f64)> for Adder {
    type Output = f64;
    extern "rust-call" fn call_once(self, args: (f64, f64)) -> f64 {
      args.0 + args.1
    }
}

fn main() {
   // let adder = Adder{};
    println!("{}", Adder{}(4, 3));
    println!("{}", Adder{}(4.2_f32, 3.1_f32));
    println!("{}", Adder{}(4.2, 3.1));
}