∀ (A : Type u_1) (M : Type u_2) [inst : Semiring A] [inst_1 : Monoid M] (x y : MonoidAlgebra A M),
  (MonoidAlgebra.toAdditive A M).toFun (x + y) =
    (MonoidAlgebra.toAdditive A M).toFun x + (MonoidAlgebra.toAdditive A M).toFun y