5 files changed, 14 insertions, 13 deletions
diff --git a/lib/expression/dune b/lib/expression/dune
index d141b7b..8bf6e62 100755
--- a/lib/expression/dune
+++ b/lib/expression/dune
@@ -7,6 +7,8 @@
    importErrors
  )
  (preprocess (pps 
-    ppx_deriving.show 
-    ppx_deriving.eq ))
+   ppx_deriving.ord
+   ppx_deriving.show 
+   ppx_deriving.eq 
+   ))
 )
diff --git a/lib/expression/sym.ml b/lib/expression/sym.ml
index 0360e8e..49e923d 100644
--- a/lib/expression/sym.ml
+++ b/lib/expression/sym.ml
@@ -1,8 +1,6 @@
 (** The signature for an expression analyzer.
 
-    Every element is mapped to a function, using the tagless final pattern.
-
- *)
+    Every element is mapped to a function, using the tagless final pattern. *)
 module type SYM_EXPR = sig
   type 'a repr
   type 'a obs
diff --git a/lib/expression/t.ml b/lib/expression/t.ml
index fec8fd7..324d515 100644
--- a/lib/expression/t.ml
+++ b/lib/expression/t.ml
@@ -6,7 +6,7 @@ type 'a window =
   | Counter
   | Previous of 'a
   | Sum of 'a
-[@@deriving show, eq]
+[@@deriving show, eq, ord]
 
 type 'a t =
   | Empty
@@ -22,7 +22,7 @@ type 'a t =
   | BOperator of binary_operator * 'a t * 'a t
   | GEquality of binary_operator * 'a t * 'a t list
   | Function' of funct * 'a t list
-[@@deriving show, eq]
+[@@deriving show, eq, ord]
 
 and binary_operator =
   | Equal
@@ -34,6 +34,7 @@ and binary_operator =
   | GT
   | And
   | Or
+[@@deriving ord]
 
 and funct =
   | Cmp
@@ -119,13 +120,13 @@ let rec cmp : ('a -> 'a -> int) -> 'a t -> 'a t -> int =
       let name_cmp = String.compare n1 n2 in
       if name_cmp = 0 then List.compare ~cmp:(cmp f) elems1 elems2 else name_cmp
   | Window (s1, l11, l12), Window (s2, l21, l22) -> (
-      match compare s1 s2 with
+      match compare_window (cmp f) s1 s2 with
       | 0 ->
           let l1_cmp = List.compare ~cmp:(cmp f) l11 l21 in
           if l1_cmp = 0 then List.compare ~cmp:(cmp f) l12 l22 else l1_cmp
       | other -> other)
   | BOperator (n1, arg11, arg12), BOperator (n2, arg21, arg22) -> begin
-      match compare n1 n2 with
+      match compare_binary_operator n1 n2 with
       | 0 -> begin
           match cmp f arg11 arg21 with
           | 0 -> cmp f arg12 arg22
diff --git a/lib/expression/t.mli b/lib/expression/t.mli
index 4e1af55..4c9e0a7 100644
--- a/lib/expression/t.mli
+++ b/lib/expression/t.mli
@@ -19,7 +19,7 @@ type 'a t =
   | BOperator of binary_operator * 'a t * 'a t
   | GEquality of binary_operator * 'a t * 'a t list
   | Function' of funct * 'a t list
-[@@deriving show, eq]
+[@@deriving show, eq, ord]
 
 and binary_operator =
   | Equal
diff --git a/lib/expression/type_of.mli b/lib/expression/type_of.mli
index 7a11582..a839c09 100644
--- a/lib/expression/type_of.mli
+++ b/lib/expression/type_of.mli
@@ -1,7 +1,7 @@
-(** This module tries to identify the type of an expression. 
+(** This module tries to identify the type of an expression.
 
-The references to data comming from the spreaedsheet cannot be evaluated and
-marked as [Extern]. *)
+    The references to data comming from the spreaedsheet cannot be evaluated and
+    marked as [Extern]. *)
 
 type t = ImportDataTypes.Types.t