Merged revisions 10358-10362,10365,10371-10373,10377,10383-10384,10394-10395,10398,10403-10408 via svnmerge from

svn+ssh://msozeau@scm.gforge.inria.fr/svn/coq/branches/TypeClasses

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  r10358 | msozeau | 2007-12-10 15:42:53 +0100 (Mon, 10 Dec 2007) | 1 line
  
  Comment grammar error
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  r10359 | msozeau | 2007-12-10 16:04:09 +0100 (Mon, 10 Dec 2007) | 7 lines
  
  The initial Type Classes patch.
  This patch introduces type classes and instance definitions a la Haskell.
  Technically, it uses the implicit arguments mechanism which was extended a bit. 
  The patch also introduces a notation for explicitely marking implicit, maximally inserted parameters.
  It includes the tactic redefinition code too (Ltac tac ::= foo redefines tac). 
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  r10360 | msozeau | 2007-12-10 16:14:30 +0100 (Mon, 10 Dec 2007) | 1 line
  
  Fix interface
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  r10361 | msozeau | 2007-12-10 16:28:19 +0100 (Mon, 10 Dec 2007) | 1 line
  
  Fix more xlate code
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  r10362 | msozeau | 2007-12-11 02:00:53 +0100 (Tue, 11 Dec 2007) | 3 lines
  
  Update coqdoc for type classes, fix proof state not being displayed on Next Obligation.
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  r10365 | msozeau | 2007-12-11 14:22:35 +0100 (Tue, 11 Dec 2007) | 3 lines
  
  Bug fixes in Instance decls.
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  r10371 | msozeau | 2007-12-12 21:17:30 +0100 (Wed, 12 Dec 2007) | 3 lines
  
  Streamline typeclass context implementation, prepare for class binders in proof statements.
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  r10372 | msozeau | 2007-12-12 22:03:38 +0100 (Wed, 12 Dec 2007) | 1 line
  
  Minor cosmetic fixes: allow sorts as typeclass param instances without parens and infer more types in class definitions
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  r10373 | msozeau | 2007-12-13 00:35:09 +0100 (Thu, 13 Dec 2007) | 2 lines
  
  Better names in g_vernac, binders in Lemmas and Context [] to introduce a typeclass context.
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  r10377 | msozeau | 2007-12-13 18:34:33 +0100 (Thu, 13 Dec 2007) | 1 line
  
  Stupid bug
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  r10383 | msozeau | 2007-12-16 00:04:48 +0100 (Sun, 16 Dec 2007) | 1 line
  
  Bug fixes in name handling and implicits, new syntax for using implicit mode in typeclass constraints
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  r10384 | msozeau | 2007-12-16 15:53:24 +0100 (Sun, 16 Dec 2007) | 1 line
  
  Streamlined implementation of instances again, the produced typeclass is a typeclass constraint. Added corresponding implicit/explicit behaviors
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  r10394 | msozeau | 2007-12-18 23:42:56 +0100 (Tue, 18 Dec 2007) | 4 lines
  
  Various fixes for implicit arguments, new "Enriching" kw to just enrich existing sets of impl args. New syntax !a to force an argument, even if not dependent.
  New tactic clrewrite using a setoid typeclass implementation to do setoid_rewrite under compatible morphisms... very experimental.
  Other bugs related to naming in typeclasses fixed. 
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  r10395 | msozeau | 2007-12-19 17:11:55 +0100 (Wed, 19 Dec 2007) | 3 lines
  
  Progress on setoids using type classes, recognize setoid equalities in hyps better.
  Streamline implementation to return more information when resolving setoids (return the results setoid).
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  r10398 | msozeau | 2007-12-20 10:18:19 +0100 (Thu, 20 Dec 2007) | 1 line
  
  Syntax change, more like Coq
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  r10403 | msozeau | 2007-12-21 22:30:35 +0100 (Fri, 21 Dec 2007) | 1 line
  
  Add right-to-left rewriting in class_setoid, fix some discharge/substitution bug, adapt test-suite to latest syntax
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  r10404 | msozeau | 2007-12-24 21:47:58 +0100 (Mon, 24 Dec 2007) | 2 lines
  
  Work on type classes based rewrite tactic.
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  r10405 | msozeau | 2007-12-27 18:51:32 +0100 (Thu, 27 Dec 2007) | 2 lines
  
  Better evar handling in pretyping, reorder theories/Program and add some tactics for dealing with subsets.
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  r10406 | msozeau | 2007-12-27 18:52:05 +0100 (Thu, 27 Dec 2007) | 1 line
  
  Forgot to add a file
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  r10407 | msozeau | 2007-12-29 17:19:54 +0100 (Sat, 29 Dec 2007) | 4 lines
  
  Generalize usage of implicit arguments in terms, up to rawconstr. Binders are decorated with binding info, either Implicit or Explicit for rawconstr. Factorizes code for typeclasses, topconstrs decorations are Default (impl|expl) or TypeClass (impl|expl) and 
  implicit quantification is resolve at internalization time, getting rid of the arbitrary prenex restriction on contexts.
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  r10408 | msozeau | 2007-12-31 00:58:50 +0100 (Mon, 31 Dec 2007) | 4 lines
  
  Fix parsing of subset binders, bugs in subtac_cases and handling of mutual defs obligations. 
  Add useful tactics to Program.Subsets.
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git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@10410 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 141 insertions, 0 deletions

diff --git a/theories/Program/Subset.v b/theories/Program/Subset.v
new file mode 100644
index 000000000..54d830c89
--- /dev/null
+++ b/theories/Program/Subset.v
@@ -0,0 +1,141 @@
+(************************************************************************)
+(*  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        *)
+(************************************************************************)
+
+Require Import Coq.Program.Utils.
+Require Import Coq.Program.Equality.
+
+(** Tactics related to subsets and proof irrelevance. *)
+
+(** Simplify dependent equality using sigmas to equality of the codomains if possible. *)
+
+Ltac simpl_existT :=
+  match goal with
+    [ H : existT _ ?x _ = existT _ ?x _ |- _ ] => 
+    let Hi := fresh H in assert(Hi:=inj_pairT2 _ _ _ _ _ H) ; clear H
+  end.
+
+Ltac simpl_existTs := repeat simpl_existT.
+
+(** The following tactics implement a poor-man's solution for proof-irrelevance: it tries to 
+   factorize every proof of the same proposition in a goal so that equality of such proofs becomes trivial. *)
+
+Ltac on_subset_proof_aux tac T :=
+  match T with
+    | context [ exist ?P _ ?p ] => try on_subset_proof_aux tac P ; tac p
+  end.
+
+Ltac on_subset_proof tac :=
+  match goal with
+    [ |- ?T ] => on_subset_proof_aux tac T
+  end.
+
+Ltac abstract_any_hyp H' p := 
+  match type of p with
+    ?X => 
+    match goal with 
+      | [ H : X |- _ ] => fail 1
+      | _ => set (H':=p) ; try (change p with H') ; clearbody H'
+    end
+  end.
+
+Ltac abstract_subset_proof := 
+  on_subset_proof ltac:(fun p => let H := fresh "eqH" in abstract_any_hyp H p ; simpl in H).
+
+Ltac abstract_subset_proofs := repeat abstract_subset_proof.
+
+Ltac pi_subset_proof_hyp p :=
+  match type of p with
+    ?X => 
+    match goal with 
+      | [ H : X |- _ ] => 
+        match p with
+          | H => fail 2
+          | _ => rewrite (proof_irrelevance X p H)
+        end
+      | _ => fail " No hypothesis with same type "
+    end
+  end.
+
+Ltac pi_subset_proof := on_subset_proof pi_subset_proof_hyp.
+
+Ltac pi_subset_proofs := repeat pi_subset_proof.
+
+(** Clear duplicated hypotheses *)
+
+Ltac clear_dup :=
+  match goal with 
+    | [ H : ?X |- _ ] => 
+      match goal with
+        | [ H' : X |- _ ] =>
+          match H' with
+            | H => fail 2 
+            | _ => clear H' || clear H
+          end
+      end
+  end.
+
+Ltac clear_dups := repeat clear_dup.
+
+(** The two preceding tactics in sequence. *)
+
+Ltac clear_subset_proofs :=
+  abstract_subset_proofs ; simpl in * |- ; pi_subset_proofs ; clear_dups.
+
+Ltac pi := repeat progress f_equal ; apply proof_irrelevance.
+
+Lemma subset_eq : forall A (P : A -> Prop) (n m : sig P), n = m <-> (`n) = (`m).
+Proof.
+  induction n.
+  induction m.
+  simpl.
+  split ; intros ; subst.
+
+  inversion H.
+  reflexivity.
+
+  pi.
+Qed.
+
+(* Somewhat trivial definition, but not unfolded automatically hence we can match on [match_eq ?A ?B ?x ?f] 
+   in tactics. *)
+
+Program Definition match_eq (A B : Type) (x : A) (fn : forall (y : A | y = x), B) : B :=
+  fn (exist _ x (refl_equal x)).
+
+(* This is what we want to be able to do: replace the originaly matched object by a new, 
+   propositionally equal one. If [fn] works on [x] it should work on any [y | y = x]. *)
+
+Lemma match_eq_rewrite : forall (A B : Type) (x : A) (fn : forall (y : A | y = x), B) 
+  (y : A | y = x),
+  match_eq A B x fn = fn y.
+Proof.
+  intros.
+  unfold match_eq.
+  f_equal.
+  destruct y.
+  (* uses proof-irrelevance *)
+  apply <- subset_eq.
+  symmetry. assumption.
+Qed.
+
+(** Now we make a tactic to be able to rewrite a term [t] which is applied to a [match_eq] using an arbitrary
+   equality [t = u], and [u] is now the subject of the [match]. *)
+
+Ltac rewrite_match_eq H := 
+  match goal with
+    [ |- ?T ] => 
+    match T with
+      context [ match_eq ?A ?B ?t ?f ] =>
+      rewrite (match_eq_rewrite A B t f (exist _ _ (sym_eq H)))
+    end
+  end.
+
+(** Otherwise we can simply unfold [match_eq] and the term trivially reduces to the original definition. *)
+
+Ltac simpl_match_eq := unfold match_eq ; simpl.
+