more functions for CCOpt

core/CCOpt.ml

@@ -58,6 +58,10 @@ let (>>=) o f = match o with
   | None -> None
   | Some x -> f x
 
+let flat_map f o = match o with
+  | None -> None
+  | Some x -> f x
+
 let (<*>) f x = match f, x with
   | None, _
   | _, None -> None
@@ -70,10 +74,22 @@ let map2 f o1 o2 = match o1, o2 with
   | _, None -> None
   | Some x, Some y -> Some (f x y)
 
+let iter f o = match o with
+  | None -> ()
+  | Some x -> f x
+
+let fold f acc o = match o with
+  | None -> acc
+  | Some x -> f acc x
+
 let to_list o = match o with
   | None -> []
   | Some x -> [x]
 
+let of_list = function
+  | x::_ -> Some x
+  | [] -> None
+
 type 'a sequence = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a printer = Buffer.t -> 'a -> unit

core/CCOpt.mli

@@ -29,6 +29,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 type 'a t = 'a option
 
 val map : ('a -> 'b) -> 'a t -> 'b t
+(** Transform the element inside, if any *)
 
 val maybe : ('a -> 'b) -> 'b -> 'a t -> 'b
 (** [maybe f x o] is [x] if [o] is [None], otherwise it's [f y] if [o = Some y] *)
@@ -45,16 +46,28 @@ val return : 'a -> 'a t
 val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
 (** Monadic bind *)
 
+val flat_map : ('a -> 'b t) -> 'a t -> 'b t
+(** Flip version of {!>>=} *)
+
 val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
 
 val (<$>) : ('a -> 'b) -> 'a t -> 'b t
 
 val map2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
 
+val iter : ('a -> unit) -> 'a t -> unit
+(** Iterate on 0 or 1 elements *)
+
+val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
+(** Fold on 0 or 1 elements *)
+
 (** {2 Conversion and IO} *)
 
 val to_list : 'a t -> 'a list
 
+val of_list : 'a list -> 'a t
+(** Head of list, or [None] *)
+
 type 'a sequence = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a printer = Buffer.t -> 'a -> unit