Monads.Monad_indexed'
type ('a, +'i, -'j) t
include Monad_generalised with type ('a, 'i, 'j, _) t := ('a, 'i, 'j) t
val return : 'a -> ('a, 'i, 'i) t
val bind : ('a, 'i, 'j) t -> ('a -> ('b, 'j, 'k) t) -> ('b, 'i, 'k) t