Integrate a few improvements on typeclasses and Program from the equations branch

and remove equations stuff which moves to a separate plugin.

Classes:
- Ability to define classes post-hoc from constants or inductive types.
- Correctly rebuild the hint database associated to local hypotheses when 
  they are changed by a [Hint Extern] in typeclass resolution.

Tactics and proofs:
- Change [revert] so that it keeps let-ins (but not [generalize]).
- Various improvements to the [generalize_eqs] tactic to make it more robust
  and produce the smallest proof terms possible.
  Move [specialize_hypothesis] in tactics.ml as it goes hand in hand with 
  [generalize_eqs].
- A few new general purpose tactics in Program.Tactics like [revert_until]
- Make transitive closure well-foundedness proofs transparent.
- More uniform testing for metas/evars in pretyping/unification.ml
  (might introduce a few changes in the contribs).

Program:
- Better sorting of dependencies in obligations.
- Ability to start a Program definition from just a type and no obligations, 
  automatically adding an obligation for this type.
- In compilation of Program's well-founded definitions, make the functional a
  separate definition for easier reasoning.
- Add a hint database for every Program populated by [Hint Unfold]s for 
  every defined obligation constant.


git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@12440 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 20 insertions, 1 deletions

diff --git a/theories/Program/Tactics.v b/theories/Program/Tactics.v
index 881297955..b3b08e067 100644
--- a/theories/Program/Tactics.v
+++ b/theories/Program/Tactics.v
@@ -43,7 +43,7 @@ Ltac do_nat n tac :=
 (** Do something on the last hypothesis, or fail *)
 
 Ltac on_last_hyp tac :=
-  match goal with [ H : _ |- _ ] => tac H || fail 1 end.
+  match goal with [ H : _ |- _ ] => first [ tac H | fail 1 ] end.
 
 (** Destructs one pair, without care regarding naming. *)
 
@@ -105,6 +105,15 @@ Ltac revert_last :=
 
 Ltac reverse := repeat revert_last.
 
+(** Reverse everything up to hypothesis id (not included). *)
+
+Ltac revert_until id :=
+  on_last_hyp ltac:(fun id' =>
+    match id' with
+      | id => idtac
+      | _ => revert id' ; revert_until id
+    end).
+
 (** Clear duplicated hypotheses *)
 
 Ltac clear_dup :=
@@ -121,6 +130,16 @@ Ltac clear_dup :=
 
 Ltac clear_dups := repeat clear_dup.
 
+(** Try to clear everything except some hyp *)
+
+Ltac clear_except hyp := 
+  repeat match goal with [ H : _ |- _ ] =>
+           match H with
+             | hyp => fail 1
+             | _ => clear H
+           end
+         end.
+
 (** A non-failing subst that substitutes as much as possible. *)
 
 Ltac subst_no_fail :=