Module Accessor.Monad

The monad signatures differ from the applicative ones in that some of the functions have an optional how argument. They always default to `Sequential, which is the behavior that interleaves side effects with monadic effects. If you override this argument to `Parallel then all the side effects are performed up front, and then the results are combined.

module type S = Accessor__.Applicative_signatures_intf.Monad_s with type ('inner, 'outer, 'kind) accessor := ('inner'outer'kind) t
module type S2 = Accessor__.Applicative_signatures_intf.Monad_s2 with type ('inner, 'outer, 'kind) accessor := ('inner'outer'kind) t