Definition Mdo {A B:Type} (ma:monad A) (mb:monad B) := ma >>= (λ _, mb).Infix ">>" := Mdo (at level 15, left associativity) : monad_scope.

Lemma lt_lt_Mdo_lt {A B:Type} (ma:monad A) (mb:monad B): Mlt ma → (Mlt mb) → Mlt (ma >> mb).