add CCList.{remove,is_empty}

src/core/CCList.ml

@@ -30,6 +30,10 @@ type 'a t = 'a list
 
 let empty = []
 
+let is_empty = function
+  | [] -> true
+  | _::_ -> false
+
 (* max depth for direct recursion *)
 let direct_depth_default_ = 1000
 
@@ -422,6 +426,19 @@ let find_idx p l = find_mapi (fun i x -> if p x then Some (i, x) else None) l
   find (fun x -> if x=3 then Some "a" else None) [1;2;4;5] = None
 *)
 
+let remove ?(eq=(=)) ~x l =
+  let rec remove' eq x acc l = match l with
+    | [] -> List.rev acc
+    | y :: tail when eq x y -> remove' eq x acc tail
+    | y :: tail -> remove' eq x (y::acc) tail
+  in
+  remove' eq x [] l
+
+(*$T
+  remove ~x:1 [2;1;3;3;2;1] = [2;3;3;2]
+  remove ~x:10 [1;2;3] = [1;2;3]
+*)
+
 let filter_map f l =
   let rec recurse acc l = match l with
   | [] -> List.rev acc

src/core/CCList.mli

@@ -30,6 +30,10 @@ type 'a t = 'a list
 
 val empty : 'a t
 
+val is_empty : _ t -> bool
+(** [is_empty l] returns [true] iff [l = []]
+    @since NEXT_RELEASE *)
+
 val map : ('a -> 'b) -> 'a t -> 'b t
 (** Safe version of map *)
 
@@ -140,6 +144,11 @@ val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
 (** [find p x] returns [Some (i,x)] where [x] is the [i]-th element of [l],
     and [p x] holds. Otherwise returns [None] *)
 
+val remove : ?eq:('a -> 'a -> bool) -> x:'a -> 'a t -> 'a t
+(** [remove ~x l] removes every instance of [x] from [l]. Tailrec.
+    @param eq equality function
+    @since NEXT_RELEASE *)
+
 val filter_map : ('a -> 'b option) -> 'a t -> 'b t
 (** Map and remove elements at the same time *)