Add map_lazy, or_, or_lazy, to_result, to_result_lazy and of_result to CCOpt

AUTHORS.adoc

@@ -18,3 +18,4 @@
 - Roma Sokolov (@little-arhat)
 - Malcolm Matalka (`orbitz`)
 - David Sheets (@dsheets)
+- Glenn Slotte (glennsl)

src/core/CCOpt.ml

@@ -13,6 +13,10 @@ let map_or ~default f = function
   | None -> default
   | Some x -> f x
 
+let map_lazy default_fn f = function
+  | None -> default_fn ()
+  | Some x -> f x
+
 let is_some = function
   | None -> false
   | Some _ -> true
@@ -54,10 +58,16 @@ let (<*>) f x = match f, x with
 
 let (<$>) = map
 
-let (<+>) a b = match a with
+let or_ ~else_ a = match a with
-  | None -> b
+  | None -> else_
   | Some _ -> a
 
+let or_lazy ~else_ a = match a with
+  | None -> else_ ()
+  | Some _ -> a
+
+let (<+>) a b = or_ ~else_:b a
+
 let choice l = List.fold_left (<+>) None l
 
 let map2 f o1 o2 = match o1, o2 with
@@ -137,6 +147,18 @@ let of_list = function
   | x::_ -> Some x
   | [] -> None
 
+let to_result err = function
+  | None -> Error err
+  | Some x -> Ok x
+
+let to_result_lazy err_fn = function
+  | None -> Error (err_fn ())
+  | Some x -> Ok x
+
+let of_result = function
+  | Error _ -> None
+  | Ok x -> Some x
+
 module Infix = struct
   let (>|=) = (>|=)
   let (>>=) = (>>=)

src/core/CCOpt.mli

@@ -9,9 +9,13 @@ val map : ('a -> 'b) -> 'a t -> 'b t
 (** Transform the element inside, if any *)
 
 val map_or : default:'b -> ('a -> 'b) -> 'a t -> 'b
-(** [map_or ~default f o] is [f x] if [o = Some x], [default otherwise]
+(** [map_or ~default f o] is [f x] if [o = Some x], [default] otherwise
     @since 0.16 *)
 
+val map_lazy : (unit -> 'b) -> ('a -> 'b) -> 'a t -> 'b
+(** [map_lazy default_fn f o] if [f o] if [o = Some x], [default_fn ()] otherwise 
+    @since NEXT_RELEASE *)
+
 val is_some : _ t -> bool
 
 val is_none : _ t -> bool
@@ -94,6 +98,14 @@ val (<$>) : ('a -> 'b) -> 'a t -> 'b t
 
 (** {2 Alternatives} *)
 
+val or_ : else_:('a t) -> 'a t -> 'a t
+(** [or_ ~else_ a] is [a] if [a] is [Some _], [else_] otherwise
+    @since NEXT_RELEASE *)
+
+val or_lazy : else_:(unit -> 'a t) -> 'a t -> 'a t
+(** [or_lazy else_ a] is [a] if [a] is [Some _], [else_ ()] otherwise
+    @since NEXT_RELEASE *)
+
 val (<+>) : 'a t -> 'a t -> 'a t
 (** [a <+> b] is [a] if [a] is [Some _], [b] otherwise *)
 
@@ -118,6 +130,15 @@ val to_list : 'a t -> 'a list
 val of_list : 'a list -> 'a t
 (** Head of list, or [None] *)
 
+val to_result : 'e -> 'a t -> ('a, 'e) Result.result
+(** @since NEXT_RELEASE *)
+
+val to_result_lazy : (unit -> 'e) -> 'a t -> ('a, 'e) Result.result
+(** @since NEXT_RELEASE *)
+
+val of_result : ('a, _) Result.result -> 'a t
+(** @since NEXT_RELEASE *)
+
 type 'a sequence = ('a -> unit) -> unit
 type 'a gen = unit -> 'a option
 type 'a printer = Format.formatter -> 'a -> unit