Lwt_pipe: conversion to/from lwt_klist

src/lwt/lwt_pipe.ml

@@ -303,6 +303,8 @@ end
 
 (** {2 Conversions} *)
 
+type 'a lwt_klist = [ `Nil | `Cons of 'a * 'a lwt_klist ] Lwt.t
+
 let of_list l : _ Reader.t =
   let p = create ~max_size:0 () in
   keep p (Lwt_list.iter_s (write p) l >>= fun () -> close p);
@@ -332,6 +334,17 @@ let of_string a =
   keep p (send 0);
   p
 
+let of_lwt_klist l =
+  let p = create ~max_size:0 () in
+  let rec next l =
+    l >>= function
+    | `Nil -> close p
+    | `Cons (x, tl) ->
+      write p x >>= fun () -> next tl
+  in
+  keep p (next l);
+  p
+
 let to_list_rev r =
   Reader.fold ~f:(fun acc x -> x :: acc) ~x:[] r
 
@@ -361,6 +374,15 @@ let join_strings ?sep r =
   let buf = Buffer.create 128 in
   to_buffer_str ?sep buf r >>>= fun () -> LwtErr.return (Buffer.contents buf)
 
+let to_lwt_klist r =
+  let rec next () =
+    read r >>= function
+    | `End -> Lwt.return `Nil
+    | `Error _ -> Lwt.return `Nil
+    | `Ok x -> Lwt.return (`Cons (x, next ()))
+  in
+  next ()
+
 (** {2 Basic IO wrappers} *)
 
 module IO = struct

src/lwt/lwt_pipe.mli

@@ -164,12 +164,16 @@ end
 
 (** {2 Conversions} *)
 
+type 'a lwt_klist = [ `Nil | `Cons of 'a * 'a lwt_klist ] Lwt.t
+
 val of_list : 'a list -> 'a Reader.t
 
 val of_array : 'a array -> 'a Reader.t
 
 val of_string : string -> char Reader.t
 
+val of_lwt_klist : 'a lwt_klist -> 'a Reader.t
+
 val to_list_rev : ('a,[>`r]) t -> 'a list LwtErr.t
 
 val to_list : ('a,[>`r]) t -> 'a list LwtErr.t
@@ -186,6 +190,9 @@ val to_string : (char, [>`r]) t -> string LwtErr.t
 
 val join_strings  : ?sep:string -> (string, [>`r]) t -> string LwtErr.t
 
+val to_lwt_klist : 'a Reader.t -> 'a lwt_klist
+(** Iterates on the reader. Errors are ignored (but stop the list). *)
+
 (** {2 Basic IO wrappers} *)
 
 module IO : sig