diff --git a/lib/util.ml b/lib/util.ml
index 29e92e0..9aea033 100644
--- a/lib/util.ml
+++ b/lib/util.ml
@@ -24,9 +24,6 @@ module ArraySet = Set.Make (ComparableArray)
 module Arraytbl = Hashtbl.Make (HashableArray)
 
 module Result_syntax = struct
-  let ( let* ) = Result.bind
-  let ( let+ ) = Result.map
-
   let ( >>= ) = Result.bind
 
   let ( >>| ) x f =  (* infix map *)
@@ -38,11 +35,6 @@ module Result_syntax = struct
     match x with
     | Ok _ as k -> k
     | Error e -> Error (f e)
-
-  let ( and+ ) x y =  (* product *)
-    match x, y with
-    | Ok a, Ok b -> Ok (a, b)
-    | Error e, Ok _ | Ok _, Error e | Error e, Error _ -> Error e
 end
 
 module Indexing = struct
@@ -71,8 +63,11 @@ module Indexing = struct
     | _ -> failwith "Invalid slice index."
 
   let reformat_slice slice shape =
-    Owl_slicing.check_slice_definition
-      (Owl_slicing.sdarray_to_sdarray slice) shape
+    match slice with
+    | [||] -> [||]
+    | xs ->
+      Owl_slicing.check_slice_definition
+        (Owl_slicing.sdarray_to_sdarray xs) shape
 
   let coords_of_slice slice shape =
     (Array.map indices_of_slice @@
diff --git a/lib/util.mli b/lib/util.mli
index 2231731..465f496 100644
--- a/lib/util.mli
+++ b/lib/util.mli
@@ -19,18 +19,12 @@ module ArraySet : sig include Set.S with type elt = int array end
 module Result_syntax : sig
   (** Result monad operator syntax. *)
 
-  val ( let* )
-    : ('a, 'e) result -> ('a -> ('b, 'e) result ) -> ('b, 'e) result
   val ( >>= )
     : ('a, 'e) result -> ('a -> ('b, 'e) result ) -> ('b, 'e) result
-  val ( let+ )
-    : ('a -> 'b) -> ('a, 'e) result -> ('b, 'e) result
   val ( >>| )
     : ('a, 'e) result -> ('a -> 'b) -> ('b, 'e) result
   val ( >>? )
     : ('a, 'e) result -> ('e -> 'f) -> ('a, 'f) result
-  val ( and+ )
-    : ('a, 'e) result -> ('b, 'e) result -> (('a * 'b), 'e) result
 end
 
 module Indexing : sig
diff --git a/test/test_indexing.ml b/test/test_indexing.ml
new file mode 100644
index 0000000..6cc06e1
--- /dev/null
+++ b/test/test_indexing.ml
@@ -0,0 +1,55 @@
+open OUnit2
+open Zarr
+
+
+let tests = [
+
+"slice from coords" >:: (fun _ ->
+  let coords =
+    [[|0; 1; 2; 3|]
+    ;[|9; 8; 7; 6|]
+    ;[|5; 4; 3; 2|]]
+  in
+  let expected =
+    Owl_types.[|
+    L [0; 9; 5];
+    L [1; 8; 4];
+    L [2; 7; 3];
+    L [3; 6; 2]
+  |]
+  in
+  assert_equal expected @@ Indexing.slice_of_coords coords;
+  assert_equal [||] @@ Indexing.slice_of_coords [])
+; 
+"coords from slice" >:: (fun _ -> 
+  let shape = [|10; 10; 11|] in
+  let slice =
+    Owl_types.[|L [0; 9; 5]; I 1; R [3; 10; 3]|]
+  in
+  let excepted =
+    [|[|0; 1; 3|]; [|0; 1; 6|]; [|0; 1; 9|]
+    ;[|9; 1; 3|]; [|9; 1; 6|]; [|9; 1; 9|]
+    ;[|5; 1; 3|]; [|5; 1; 6|]; [|5; 1; 9|]|]
+  in
+  assert_equal excepted @@ Indexing.coords_of_slice slice shape;
+  assert_equal [|[||]|] @@ Indexing.coords_of_slice [||] shape)
+;
+"compute slice shape" >:: (fun _ ->
+  let shape = [|10; 10; 10|] in
+  let slice =
+    Owl_types.[|L [0; 9; 5]; I 1; R [2; 9; 1]|]
+  in
+  assert_equal [|3; 1; 8|] @@ Indexing.slice_shape slice shape;
+  assert_equal [||] @@ Indexing.slice_shape [||] shape)
+;
+"cartesian product" >:: (fun _ ->
+  let ll = [[1; 2]; [3; 8]; [9; 4]] in
+  let expected =
+    [[1; 3; 9]; [1; 3; 4]; [1; 8; 9]; [1; 8; 4]
+    ;[2; 3; 9]; [2; 3; 4]; [2; 8; 9]; [2; 8; 4]]
+  in
+  assert_equal expected @@ Indexing.cartesian_prod ll;
+  let ll = [['a'; 'b']; ['z'; 'o']] in
+  let expected = [['a'; 'z']; ['a'; 'o']; ['b'; 'z']; ['b'; 'o']] in
+  assert_equal expected @@ Indexing.cartesian_prod ll)
+]
diff --git a/test/test_zarr.ml b/test/test_zarr.ml
index d939747..f287238 100644
--- a/test/test_zarr.ml
+++ b/test/test_zarr.ml
@@ -3,6 +3,7 @@ open OUnit2
 
 let () =
   let suite = "Run All tests" >:::
-      Test_node.tests
+      Test_node.tests @
+      Test_indexing.tests
   in
   run_test_tt_main suite