What do you mean by specialized? Don't know the equivalent of flatten in Haskell, but if you want a signature then it is something like: def flatten(m: M[M

What do you mean by specialized? Don't know the equivalent of flatten in Haskell, but if you want a signature then it is something like: def flatten(m: M[M[A]]): M[A] Or another way of thinking about it ... flatten(m) == flatMap(m)(x => x) So basically, in order to define a monad, implementing flatMap is equivalent to implementing flatten. And I think that "flatten" as a verb is very intuitive, although intuitiveness is subjective since it's tightly related to familiarity - but flatten has been used in many languages as an operation available for collections and it works for monads in general just as well.