Handy use of Rust's declarative macro

max_value.rs

trait MaxValue {
  fn max_value() -> Self;
}

macro_rules! max_impl {
  ($t:ty) => {
    impl crate::MaxValue for $t {
      fn max_value() -> Self {
        <$t>::max_value()
      }
    }
  };
}

// unsigned integers
max_value!(u8);
max_value!(u16);
max_value!(u32);
max_value!(u64);
max_value!(usize);
// signed integers
max_value!(i8);
max_value!(i16);
max_value!(i32);
max_value!(i64);
max_value!(isize);
// floats
max_value!(f32);
max_value!(f64);