1 files changed, 23 insertions, 1 deletions
diff --git a/theories/FSets/OrderedTypeEx.v b/theories/FSets/OrderedTypeEx.v
index 03171396..03e3ab83 100644
--- a/theories/FSets/OrderedTypeEx.v
+++ b/theories/FSets/OrderedTypeEx.v
@@ -11,7 +11,7 @@
  * Institution: LRI, CNRS UMR 8623 - Université Paris Sud
  *              91405 Orsay, France *)
 
-(* $Id: OrderedTypeEx.v 10739 2008-04-01 14:45:20Z herbelin $ *)
+(* $Id: OrderedTypeEx.v 11699 2008-12-18 11:49:08Z letouzey $ *)
 
 Require Import OrderedType.
 Require Import ZArith.
@@ -34,6 +34,7 @@ Module Type UsualOrderedType.
  Axiom lt_trans : forall x y z : t, lt x y -> lt y z -> lt x z.
  Axiom lt_not_eq : forall x y : t, lt x y -> ~ eq x y.
  Parameter compare : forall x y : t, Compare lt eq x y.
+ Parameter eq_dec : forall x y : t, { eq x y } + { ~ eq x y }.
 End UsualOrderedType.
 
 (** a [UsualOrderedType] is in particular an [OrderedType]. *)
@@ -68,6 +69,8 @@ Module Nat_as_OT <: UsualOrderedType.
     intro; constructor 3; auto.
   Defined.
 
+  Definition eq_dec := eq_nat_dec.
+
 End Nat_as_OT.
 
 
@@ -99,6 +102,8 @@ Module Z_as_OT <: UsualOrderedType.
     apply GT; unfold lt, Zlt; rewrite <- Zcompare_Gt_Lt_antisym; auto.
   Defined.
 
+  Definition eq_dec := Z_eq_dec.
+
 End Z_as_OT.
 
 (** [positive] is an ordered type with respect to the usual order on natural numbers. *) 
@@ -140,6 +145,11 @@ Module Positive_as_OT <: UsualOrderedType.
   rewrite <- Pcompare_antisym; rewrite H; auto.
   Defined.
 
+  Definition eq_dec : forall x y, { eq x y } + { ~ eq x y }.
+  Proof.
+   intros; unfold eq; decide equality.
+  Defined.
+
 End Positive_as_OT.
 
 
@@ -183,6 +193,11 @@ Module N_as_OT <: UsualOrderedType.
    destruct (Nleb x y); intuition.
   Defined.
 
+  Definition eq_dec : forall x y, { eq x y } + { ~ eq x y }.
+  Proof.
+   intros. unfold eq. decide equality. apply Positive_as_OT.eq_dec.
+  Defined.
+
 End N_as_OT.
 
 
@@ -243,5 +258,12 @@ Module PairOrderedType(O1 O2:OrderedType) <: OrderedType.
  apply GT; unfold lt; auto.
  Defined.
 
+ Definition eq_dec : forall x y : t, {eq x y} + {~ eq x y}.
+ Proof.
+ intros; elim (compare x y); intro H; [ right | left | right ]; auto.
+ auto using lt_not_eq.
+ assert (~ eq y x); auto using lt_not_eq, eq_sym.
+ Defined.
+
 End PairOrderedType.