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, 110 insertions, 0 deletions

diff --git a/pretyping/term_dnet.mli b/pretyping/term_dnet.mli
new file mode 100644
index 0000000000..ccf9624814
--- /dev/null
+++ b/pretyping/term_dnet.mli
@@ -0,0 +1,110 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+(* $Id:$ *)
+
+(*i*)
+open Term
+open Sign
+open Libnames
+open Mod_subst
+(*i*)
+
+(* Dnets on constr terms. 
+   
+   An instantiation of Dnet on (an approximation of) constr. It
+   associates a term (possibly with Evar) with an
+   identifier. Identifiers must be unique (no two terms sharing the
+   same ident), and there must be a way to recover the full term from
+   the identifier (function constr_of).
+
+   Optionally, a pre-treatment on terms can be performed before adding
+   or searching (reduce). Practically, it is used to do some kind of
+   delta-reduction on terms before indexing them.
+
+   The results returned here are perfect, since post-filtering is done
+   inside here.
+
+   See lib/dnet.mli for more details.
+*)
+
+(* Identifiers to store (right hand side of the association) *)
+module type IDENT = sig
+  type t
+  val compare : t -> t -> int
+
+  (* how to substitute them for storage *)
+  val subst : substitution -> t -> t
+
+  (* how to recover the term from the identifier *)
+  val constr_of : t -> constr
+end
+
+(* Options : *)
+module type OPT = sig
+
+  (* pre-treatment to terms before adding or searching *)
+  val reduce : constr -> constr
+
+  (* direction of post-filtering w.r.t sort subtyping : 
+     - true means query <= terms in the structure
+     - false means terms <= query
+ *)
+  val direction : bool
+end
+
+module type S =
+sig
+  type t
+  type ident
+
+  (* results of filtering : identifier, a context (term with Evar
+     hole) and the substitution in that context*)
+  type result = ident * (constr*existential_key) * Termops.subst
+
+  val empty : t
+
+  (* [add c i dn] adds the binding [(c,i)] to [dn]. [c] can be a
+     closed term or a pattern (with untyped Evars). No Metas accepted *)
+  val add : constr -> ident -> t -> t
+
+  (* merge of dnets. Faster than re-adding all terms *)
+  val union : t -> t -> t
+
+  val subst : substitution -> t -> t
+
+  (* 
+   * High-level primitives describing specific search problems 
+   *)
+
+  (* [search_pattern dn c] returns all terms/patterns in dn
+     matching/matched by c *)
+  val search_pattern : t -> constr -> result list
+   
+  (* [search_concl dn c] returns all matches under products and
+     letins, i.e. it finds subterms whose conclusion matches c. The
+     complexity depends only on c ! *)
+  val search_concl : t -> constr -> result list
+
+  (* [search_head_concl dn c] matches under products and applications
+     heads. Finds terms of the form [forall H_1...H_n, C t_1...t_n]
+     where C matches c *)
+  val search_head_concl : t -> constr -> result list
+    
+  (* [search_eq_concl dn eq c] searches terms of the form [forall
+     H1...Hn, eq _ X1 X2] where either X1 or X2 matches c *)
+  val search_eq_concl : t -> constr -> constr -> result list
+
+  (* [find_all dn] returns all idents contained in dn *)
+  val find_all : t -> ident list
+end
+
+module Make :
+  functor (Ident : IDENT) ->
+  functor (Opt : OPT) ->
+    S with type ident = Ident.t