Parameter Make_indexed.X

Indexed monad, in the style of Atkey. The second and third parameters are composed across all computation. To see this more clearly, you can look at the type of bind:

  val bind : ('a, 'i, 'j) t -> f:('a -> ('b, 'j, 'k) t) -> ('b, 'i, 'k) t

and isolate some of the type variables to see their individual behaviors:

  val bind : 'a             -> f:('a ->  'b           ) ->  'b
  val bind :      'i, 'j    ->               'j, 'k     ->     'i, 'k

For more information on Atkey-style indexed monads, see:

  Parameterised Notions of Computation
  Robert Atkey
  http://bentnib.org/paramnotions-jfp.pdf