[Haskell-cafe] data EitherF m1 m2 a = LeftF (m1 a) | RightF (m2 a)

Hi, I am wondering if there is a library with a datatype like the following defined: data EitherF m1 m2 a = LeftF (m1 a) | RightF (m2 a) I could not find anything with Hoogle. Does anybody know such a thing? Thank you & best, Daniel