Macro fixed_score_set 

macro_rules! fixed_score_set {
    ($($weight:expr => $metric:expr),+ $(,)?) => { ... };
}

Declare a fixed set of weight => metric pairs (Layer 1).

Each weight is validated > 0 via GtZero. The macro normalizes weights and returns a FixedScoreSet directly.

Example

let gc  = metric("gc") .measure().by(...).map01().by(...);
let len = metric("len").measure().by(...).map01().by(...);

let ms = fixed_score_set! {
    2.0 => gc,
    3.0 => len,
}?;