DISCLAIMER

==========

This big patch is commited here with a HUGE experimental tag on it. It
is probably not a finished job. The aim of committing it now, as
agreed with Hugo, is to get some feedback from potential users to
identify more clearly the directions the implementation could take. So
please feel free to mail me any remarks, bug reports or advices at
<puech@cs.unibo.it>.

Here are the changes induced by it :

For the user
============

* Search tools have been reimplemented to be faster and more
  general. Affected are [SearchPattern], [SearchRewrite] and [Search]
  (not [SearchAbout] yet). Changes are:

  - All of them accept general constructions, and previous syntactical
    limitations are abolished. In particular, one can for example
    [SearchPattern (nat -> Prop)], which will find [isSucc], but also
    [le], [gt] etc.

  - Patterns are typed. This means that you cannot search mistyped
    expressions anymore. I'm not sure if it's a good or a bad thing
    though (especially regarding coercions)...

* New tool to automatically infer (some) Record/Typeclasses instances.
  Usage : [Record/Class *Infer* X := ...] flags a record/class as
  subject to instance search. There is also an option to
  activate/deactivate the search [Set/Unset Autoinstance].  It works
  by finding combinations of definitions (actually all kinds of
  objects) which forms a record instance, possibly parameterized. It
  is activated at two moments:

  - A complete search is done when defining a new record, to find all
    possible instances that could have been formed with past
    definitions. Example: 

      Require Import List.
      Record Infer Monoid A (op:A->A->A) e := 
        { assoc : forall x y z, op x (op y z) = op (op x y) z; 
          idl : forall x, x = op x e ; 
          idr : forall x, x = op e x }.

      new instance Monoid_autoinstance_1 : (Monoid nat plus 0)
      [...]

  - At each new declaration (Definition, Axiom, Inductive), a search
    is made to find instances involving the new object. Example:

      Parameter app_nil_beg : forall A (l:list A), l = nil ++ l.

      new instance Build_Monoid_autoinstance_12 :
      (forall H : Type, Monoid (list H) app nil) :=
      (fun H : Type =>
      Build_Monoid (list H) app nil ass_app (app_nil_beg H)
      (app_nil_end H))


For the developper
==================

* New yet-to-be-named datastructure in [lib/dnet.ml]. Should do
  efficient one-to-many or many-to-one non-linear first-order
  filtering, faster than traditional methods like discrimination nets
  (so yes, the name of the file should probably be changed).

* Comes with its application to Coq's terms
  [pretyping/term_dnet.ml]. Terms are represented so that you can
  search for patterns under products as fast as you would do not under
  products, and facilities are provided to express other kind of
  searches (head of application, under equality, whatever you need
  that can be expressed as a pattern)

* A global repository of all objects defined and imported is
  maintained [toplevel/libtypes.ml], with all search facilities
  described before.

* A certain kind of proof search in [toplevel/autoinstance.ml]. For
  the moment it is specialized on finding instances, but it should be
  generalizable and reusable (more on this in a few months :-).


The bad news
============

* Compile time should increase by 0 to 15% (depending on the size of
  the Requires done). This could be optimized greatly by not
  performing substitutions on modules which are not functors I
  think. There may also be some inefficiency sources left in my code
  though...

* Vo's also gain a little bit of weight (20%). That's inevitable if I
  wanted to store the big datastructure of objects, but could also be
  optimized some more.


git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@11794 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 65 insertions, 4 deletions

diff --git a/pretyping/termops.ml b/pretyping/termops.ml
index 987db88b18..e3b8a166c7 100644
--- a/pretyping/termops.ml
+++ b/pretyping/termops.ml
@@ -951,16 +951,77 @@ let base_sort_cmp pb s0 s1 =
     | _ -> false
 
 (* eq_constr extended with universe erasure *)
-let rec constr_cmp cv_pb t1 t2 =
+let compare_constr_univ f cv_pb t1 t2 = 
   match kind_of_term t1, kind_of_term t2 with
       Sort s1, Sort s2 -> base_sort_cmp cv_pb s1 s2
     | Prod (_,t1,c1), Prod (_,t2,c2) -> 
-	constr_cmp Reduction.CONV t1 t2 & 
-	  constr_cmp cv_pb c1 c2
-    | _ -> compare_constr (constr_cmp Reduction.CONV) t1 t2
+	f Reduction.CONV t1 t2 & f cv_pb c1 c2
+    | _ -> compare_constr (f Reduction.CONV) t1 t2
+
+let rec constr_cmp cv_pb t1 t2 = compare_constr_univ constr_cmp cv_pb t1 t2
 
 let eq_constr = constr_cmp Reduction.CONV
 
+(* App(c,[t1,...tn]) -> ([c,t1,...,tn-1],tn)
+   App(c,[||]) -> ([],c) *)
+let split_app c = match kind_of_term c with
+    App(c,l) -> 
+      let len = Array.length l in
+      if len=0 then ([],c) else
+	let last = Array.get l (len-1) in
+	let prev = Array.sub l 0 (len-1) in
+	c::(Array.to_list prev), last
+  | _ -> assert false
+
+let hdtl l = List.hd l, List.tl l
+
+type subst = (rel_context*constr) Intmap.t
+
+exception CannotFilter
+
+let filtering env cv_pb c1 c2 =
+  let evm = ref Intmap.empty in
+  let define cv_pb e1 ev c1 = 
+    try let (e2,c2) = Intmap.find ev !evm in
+    let shift = List.length e1 - List.length e2 in
+    if constr_cmp cv_pb c1 (lift shift c2) then () else raise CannotFilter
+    with Not_found -> 
+      evm := Intmap.add ev (e1,c1) !evm
+  in
+  let rec aux env cv_pb c1 c2 =
+    match kind_of_term c1, kind_of_term c2 with
+      | App _, App _ -> 
+	  let ((p1,l1),(p2,l2)) = (split_app c1),(split_app c2) in
+	  aux env cv_pb l1 l2; if p1=[] & p2=[] then () else
+	      aux env cv_pb (applist (hdtl p1)) (applist (hdtl p2))
+      | Prod (n,t1,c1), Prod (_,t2,c2) ->
+	  aux env cv_pb t1 t2;
+	  aux ((n,None,t1)::env) cv_pb c1 c2
+      | _, Evar (ev,_) -> define cv_pb env ev c1
+      | Evar (ev,_), _ -> define cv_pb env ev c2
+      | _ -> 
+	  if compare_constr_univ 
+	  (fun pb c1 c2 -> aux env pb c1 c2; true) cv_pb c1 c2 then () 
+	  else raise CannotFilter
+	  (* TODO: le reste des binders *)
+  in
+  aux env cv_pb c1 c2; !evm
+
+let decompose_prod_letin : constr -> int * rel_context * constr = 
+  let rec prodec_rec i l c = match kind_of_term c with
+    | Prod (n,t,c)    -> prodec_rec (succ i) ((n,None,t)::l) c
+    | LetIn (n,d,t,c) -> prodec_rec (succ i) ((n,Some d,t)::l) c
+    | Cast (c,_,_)    -> prodec_rec i l c
+    | _               -> i,l,c in
+  prodec_rec 0 []
+
+let align_prod_letin c a : rel_context * constr =
+  let (lc,_,_) = decompose_prod_letin c in
+  let (la,l,a) = decompose_prod_letin a in
+  if not (la >= lc) then invalid_arg "align_prod_letin";
+  let (l1,l2) = Util.list_chop lc l in
+  l2,it_mkProd_or_LetIn a l1
+    
 (* On reduit une serie d'eta-redex de tete ou rien du tout  *)
 (* [x1:c1;...;xn:cn]@(f;a1...an;x1;...;xn) --> @(f;a1...an) *)
 (* Remplace 2 versions précédentes buggées                  *)