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

3 files changed, 26 insertions, 0 deletions

diff --git a/tactics/extratactics.ml4 b/tactics/extratactics.ml4
index 37498b13f0..d595bfe43e 100644
--- a/tactics/extratactics.ml4
+++ b/tactics/extratactics.ml4
@@ -505,6 +505,10 @@ TACTIC EXTEND generalize_eqs_vars
 | ["generalize_eqs_vars" hyp(id) ] -> [ abstract_generalize id ~generalize_vars:true ]
 END
 
+TACTIC EXTEND dependent_pattern
+| ["dependent_pattern" constr(c) ] -> [ dependent_pattern c ]
+END
+
 TACTIC EXTEND conv
 | ["conv" constr(x) constr(y) ] -> [ conv x y ]
 END
diff --git a/tactics/tactics.ml b/tactics/tactics.ml
index 36ec22ee61..02d9544f00 100644
--- a/tactics/tactics.ml
+++ b/tactics/tactics.ml
@@ -2073,6 +2073,26 @@ let abstract_generalize id ?(generalize_vars=true) gl =
 			 tclMAP (fun id -> tclTRY (generalize_dep (mkVar id))) vars]) gl
 	    else tac gl
 	      
+let dependent_pattern c gl =
+  let cty = pf_type_of gl c in
+  let deps = 
+    match kind_of_term cty with
+    | App (f, args) -> Array.to_list args
+    | _ -> []
+  in
+  let varname c = match kind_of_term c with
+    | Var id -> id
+    | _ -> id_of_string (hdchar (pf_env gl) c)
+  in
+  let mklambda ty (c, id, cty) =
+    let conclvar = subst_term_occ all_occurrences c ty in
+      mkNamedLambda id cty conclvar
+  in
+  let subst = (c, varname c, cty) :: List.map (fun c -> (c, varname c, pf_type_of gl c)) deps in
+  let concllda = List.fold_left mklambda (pf_concl gl) subst in 
+  let conclapp = applistc concllda (List.rev_map pi1 subst) in
+    convert_concl_no_check conclapp DEFAULTcast gl
+      
 let occur_rel n c = 
   let res = not (noccurn n c) in
   res
diff --git a/tactics/tactics.mli b/tactics/tactics.mli
index 58df7155e7..1ebaec3b4e 100644
--- a/tactics/tactics.mli
+++ b/tactics/tactics.mli
@@ -365,5 +365,7 @@ val admit_as_an_axiom : tactic
 
 val abstract_generalize : identifier -> ?generalize_vars:bool -> tactic
 
+val dependent_pattern : constr -> tactic
+
 val register_general_multi_rewrite : 
   (bool -> evars_flag -> constr with_ebindings -> clause -> tactic) -> unit