Via_map_and_join.Reqinclude Preface_specs.Indexed_monad.WITH_RETURN
with type ('a, 'index) t := ('a, 'index) tval return : 'a -> ('a, 'index) tLift a value into a t.
include Preface_specs.Indexed_bind.WITH_MAP_AND_JOIN
with type ('a, 'index) t := ('a, 'index) tval neutral : ('a, 'index) tThe neutral element of the t.