Binary_searchable.Makeval binary_search : 
  ?pos:int ->
  ?len:int ->
  T.t ->
  compare:(T.elt -> 'key -> int) ->
  [ `Last_strictly_less_than
  | `Last_less_than_or_equal_to
  | `Last_equal_to
  | `First_equal_to
  | `First_greater_than_or_equal_to
  | `First_strictly_greater_than ] ->
  'key ->
  int optionSee Binary_search.binary_search in binary_search.ml