Fixed length type.

src/IO_iter.ml

@@ -92,7 +92,7 @@ let head p =
   | None        -> None
 
 let sum source = fold ~init:0 ~f:(+) source
-let len source = fold ~init:0 ~f:(fun c i -> c + 1) source
+let length source = fold ~init:0 ~f:(fun c _ -> c + 1) source
 
 let rec any source =
   match next source with

src/IO_iter.mli

@@ -16,7 +16,7 @@ val fold : init:'a -> f:('a -> 'b -> 'a) -> ('c, 'b, 'd) node -> 'a
 val head : (void, 'b, 'r) node -> 'b option
 val iota : int -> (void, int, unit) node
 val last : (void, 'b, 'r) node -> 'b option
-val len : (void, int, 'r) node -> int
+val length : (void, 'b, 'r) node -> int
 val list : 'a list -> (void, 'a, unit) node
 val map : ('a -> 'b) -> ('a, 'b, 'r) node
 val nth : int -> ('a, 'b, 'r) node -> 'b option

tests/test_io_iter.ml

@@ -5,7 +5,7 @@ open IO.Iter
 
 let test_sinks () = begin
   print_endline "io_iter: test_sinks";
-  assert (len (iota 10) = 10);
+  assert (length (iota 10) = 10);
   assert (sum (iota 10) = 45);
   assert (last (range 20 26) = Some 25);
 end
@@ -23,7 +23,7 @@ let test_api () = begin
 
   assert (fold ~init:0 ~f:(+) (iota 1000000 => filter odd) = 250000000000);
   assert (collect (count => take 5) = [0; 1; 2; 3; 4]);
-  assert (len (list (List.range 10 100) => take 10 => tail) = 9);
+  assert (length (list (List.range 10 100) => take 10 => tail) = 9);
   assert (sum (list (List.range 10 100) => take 10 => filter even) = 70);
   assert (fold ~init:0 ~f:(+) (list (List.range 50 100) => take 10) = 545);
   assert (head (range 10 100) = Some 10);