Various little improvements:

- A new [dependent pattern] tactic to do a pattern on an object in an
inductive family and generalize by both the indexes and the object
itself. Useful to prepare a goal for elimination with a dependent
principle.
- Better dependent elimination simplification tactic that doesn't
throw away non-dependent equalities if they can't be injected.
- Add [fold_sub] and [unfold_sub] tactics for folding/unfolding
well-founded definitions using measures built by Program.


git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@11420 85f007b7-540e-0410-9357-904b9bb8a0f7

2 files changed, 21 insertions, 6 deletions

diff --git a/theories/Program/Equality.v b/theories/Program/Equality.v
index 2b914ace7..d37fd62f6 100644
--- a/theories/Program/Equality.v
+++ b/theories/Program/Equality.v
@@ -359,9 +359,9 @@ Definition block_dep_elim {A : Type} (a : A) := a.
 
 Ltac simplify_one_dep_elim_term c :=
   match c with
-    | @JMeq ?A ?a ?A ?b -> _ => refine (simplification_heq _ _ _ _ _)
+    | @JMeq _ _ _ _ -> _ => refine (simplification_heq _ _ _ _ _)
     | ?t = ?t -> _ => intros _ || refine (simplification_K _ t _ _)
-    | eq (existT ?P ?p _) (existT ?P ?p _) -> _ => refine (simplification_existT _ _ _ _ _ _ _)
+    | eq (existT _ _ _) (existT _ _ _) -> _ => refine (simplification_existT _ _ _ _ _ _ _)
     | ?x = ?y -> _ => (* variables case *)
       (let hyp := fresh in intros hyp ;
         move dependent hyp before x ;
@@ -370,11 +370,12 @@ Ltac simplify_one_dep_elim_term c :=
         move dependent hyp before y ;
           generalize dependent y ; refine (solution_right _ _ _ _) ; intros until 0)
     | @eq ?A ?t ?u -> ?P => apply (noConfusion (I:=A) P)
-    | ?f ?x = ?g ?y -> _ => let H := fresh in intros H ; injection H ; clear H
+    | ?f ?x = ?g ?y -> _ => let H := fresh in progress (intros H ; injection H ; clear H)
     | ?t = ?u -> _ => let hyp := fresh in
       intros hyp ; elimtype False ; discriminate
     | ?x = ?y -> _ => let hyp := fresh in
-      intros hyp ; case hyp ; clear hyp
+      intros hyp ; (try (clear hyp ; (* If non dependent, don't clear it! *) fail 1)) ;
+        case hyp ; clear hyp
     | block_dep_elim ?T => fail 1 (* Do not put any part of the rhs in the hyps *)
     | _ => intro
   end.
diff --git a/theories/Program/FunctionalExtensionality.v b/theories/Program/FunctionalExtensionality.v
index 440217bfe..8bd2dfb90 100644
--- a/theories/Program/FunctionalExtensionality.v
+++ b/theories/Program/FunctionalExtensionality.v
@@ -22,7 +22,7 @@ Require Import Coq.Program.Equality.
 Set Implicit Arguments.
 Unset Strict Implicit.
 
-(** The converse of functional equality. *)
+(** The converse of functional extensionality. *)
 
 Lemma equal_f : forall A B : Type, forall (f g : A -> B), 
   f = g -> forall x, f x = g x.
@@ -32,7 +32,7 @@ Proof.
   auto.
 Qed.
 
-(** Statements of functional equality for simple and dependent functions. *)
+(** Statements of functional extensionality for simple and dependent functions. *)
 
 Axiom fun_extensionality_dep : forall A, forall B : (A -> Type), 
   forall (f g : forall x : A, B x), 
@@ -106,4 +106,18 @@ Proof.
   rewrite H0 ; auto.
 Qed.
 
+(** Tactics to fold/unfold definitions based on [Fix_measure_sub]. *)
 
+Ltac fold_sub f :=
+  match goal with
+    | [ |- ?T ] => 
+      match T with
+        appcontext C [ @Fix_measure_sub _ _ _ _ ?arg ] => 
+        let app := context C [ f arg ] in
+         change app
+      end
+  end.
+
+Ltac unfold_sub f fargs := 
+  set (call:=fargs) ; unfold f in call ; unfold call ; clear call ; 
+  rewrite fix_sub_measure_eq_ext ; repeat fold_sub fargs ; simpl proj1_sig.