option.mli

(*
    Copyright © 2011 MLstate

    This file is part of OPA.

    OPA is free software: you can redistribute it and/or modify it under the
    terms of the GNU Affero General Public License, version 3, as published by
    the Free Software Foundation.

    OPA is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for
    more details.

    You should have received a copy of the GNU Affero General Public License
    along with OPA. If not, see <http://www.gnu.org/licenses/>.
*)
(*
    @author Rudy Sicard
    @author Pascal Rigaux
    @author Mehdi Bouaziz
    @author Mathieu Barbin
    @author François-Régis Sinot
    @author Henri Binsztok
*)

val default : 'a -> 'a option -> 'a
val default_lazy : 'a Lazy.t -> 'a option -> 'a
(** true if the argument is None*)
val is_none : 'a option -> bool
(** true if the argument is Some _*)
val is_some : 'a option -> bool

(**
   [if_none o a b] {[if is_none then a else b]}
*)
val if_none : 'a option -> 'b -> 'b -> 'b

(**
   if_some o a b <=> if is_some then a else b
*)
val if_some : 'a option -> 'b -> 'b -> 'b
val get : 'a option -> 'a
val get_exn : exn -> 'a option -> 'a
val map : ('a -> 'b) -> 'a option -> 'b option
val map2 : ('a -> 'b -> 'c) -> 'a option -> 'b option -> 'c option

(** apply the optional function *)
val apply : ('a -> 'a) option -> 'a -> 'a


val fold : ('a -> 'b -> 'a) -> 'a -> 'b option -> 'a
val fold_right : ('b -> 'acc -> 'acc) -> 'b option -> 'acc -> 'acc
val foldmap : ('a -> 'b -> 'a * 'c) -> 'a -> 'b option -> 'a * 'c option

(** Like foldmap but returns the same object physically if
    the traverse function returns the same object.
    Used for optimizing traversal constructions *)
val foldmap_stable :
  ('a -> 'b -> 'a * 'b) -> 'a -> 'b option -> 'a * 'b option

val iter : ('a -> unit) -> 'a option -> unit

(**
   Like map but can change a [Some(v)] to a [none]
*)
val bind : ('a -> 'b option) -> 'a option -> 'b option
val to_list : 'a option -> 'a list
val default_map : 'a -> ('b -> 'a) -> 'b option -> 'a
val default_lazy_map : 'a Lazy.t -> ('b -> 'a) -> 'b option -> 'a
val join : 'a option option -> 'a option
val make_compare : ('a -> 'b -> int) -> 'a option -> 'b option -> int
val merge : ('a -> 'a -> 'a) -> 'a option -> 'a option -> 'a option
val to_string : ('a -> string) -> 'a option -> string

(**
   [pp_none] Print [none] or directly the value if Some
*)
val pp_none :
  (Format.formatter -> 'a -> unit) -> Format.formatter -> 'a option -> unit

(**
   [pp] does not print anything for [None], and print the value if [Some]
*)
val pp : ('a -> 'b -> unit) -> 'a -> 'b option -> unit

(**
   [pp_sep sep pp fmt opt]
   Does not print anything for [None].
   Print the separator, and the value if [Some]
*)
val pp_sep :
  (unit, Format.formatter, unit) format ->
  (Format.formatter -> 'a -> unit) ->
  Format.formatter -> 'a option -> unit

(**
   Print the default if [None], and the value if [Some]
*)
val pp_default : 'a -> ('b -> 'a -> 'c) -> 'b -> 'a option -> 'c

(**
   Print [None] and [Some value]
*)
val pp_meta :
  (Format.formatter -> 'a -> unit) -> Format.formatter -> 'a option -> unit

val exists : ('a -> bool) -> 'a option -> bool
val for_all : ('a -> bool) -> 'a option -> bool