Why not? If (+) is numeric addition and coercion is free then {} is NaN and so is {} and so is NaN + (anything) and so is (anything) + NaN. Which is not to say

Why not? If (+) is numeric addition and coercion is free then {} is NaN and so is {} and so is NaN + (anything) and so is (anything) + NaN. Which is not to say that it's a good choice, but instead to say that the badness stems from overloading (+) too much and having free coercion.