Player: struct {
  x: float
  y: float
  name: str?
}

Moving: trait {
  move: fun(self, float, float)
}

implement Player: Moving {
  move: fun(self, dx: float, dy: float) {
    self x += dx
    self y += dy
  }
}

niels := new Player {
  x: 100
  y: 200
}

niels name = "boss man"