Monad.Basic_indexed
type ('a, 'i, 'j) t
val bind : ('a, 'i, 'j) t -> f:('a -> ('b, 'j, 'k) t) -> ('b, 'i, 'k) t
val map : [ `Custom of ('a, 'i, 'j) t -> f:('a -> 'b) -> ('b, 'i, 'j) t | `Define_using_bind ]
val return : 'a -> ('a, 'i, 'i) t