op ->

impl Vec3 {
  static op +(a: Vec3, b: Vec3) -> Vec3 => Vec3(a.x + b.x, a.y + b.y, a.z + b.z)
  static op *(v: Vec3, k: f32) -> Vec3 => Vec3(v.x * k, v.y * k, v.z * k)
  static op -(v: Vec3) -> Vec3 => v * -1.0
  op [](i: usize) -> f32 { … }            // read by index
  var op [](i: usize) -> &var f32 { … }   // write by index
  op ()(t: f32) -> Vec3 { … }             // call as a function
  static op <=>(a: Vec3, b: Vec3) -> Ordering { … }
  op as Vec4 => Vec4(x, y, z, 1.0)
}

@repr(i64)
data Money { minor: i64 }

impl Repr<i64> for Money {
  fn toRepr() -> i64 => minor
  static fn fromRepr(v: i64) -> Money | DecodeError => Money{ minor: v }
}