FSet/OrderedType now includes an eq_dec, and hence become an extension of DecidableType

 After lots of hesitations, OrderedType now requires this "eq_dec" field, which
 is redundant (can be deduced from "compare"), but allows the subtyping relation
 DecidableType <= OrderedType, and hence WS <= S : ordered sets are now truly
 extensions of weak sets. Of course this change introduces a last-minute
 incompatibility, but:

  - There is a clear gain in term of functionnality / simplicity.
  - FSets 8.2 already needs some adaptations when compared with 8.1, so it's
    the right time to push such incompatible changes.
  - Transition shouldn't be too hard: the old OrderedType still exists under
    the name MiniOrderedType, and functor MOT_to_OT allows to convert from
    one to the other.

 Beware, for a FSetInterface.WS (resp. S) to be coercible to a DecidableType
 (resp. OrderedType), an eq_dec on sets is now required in these interfaces
 and in the implementations. In pratice, it is really easy to build from
 equal and equal_1 and equal_2.

 Some name changes : in FSetFacts, old WFacts now correspond to WFacts_fun,
 while WFacts now expects only one argument (WFacts M := WFacts_fun M.E M).
 Idem with WDecide, WProperties and WEqProperties.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@11693 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 9 insertions, 12 deletions

diff --git a/theories/FSets/FSetFacts.v b/theories/FSets/FSetFacts.v
index 6afb8fcb7..8c692bd07 100644
--- a/theories/FSets/FSetFacts.v
+++ b/theories/FSets/FSetFacts.v
@@ -21,11 +21,9 @@ Require Export FSetInterface.
 Set Implicit Arguments.
 Unset Strict Implicit.
 
-(** First, a functor for Weak Sets. Since the signature [WS] includes
-    an EqualityType and not a stronger DecidableType, this functor 
-    should take two arguments in order to compensate this. *)
+(** First, a functor for Weak Sets in functorial version. *)
 
-Module WFacts (Import E : DecidableType)(Import M : WSfun E).
+Module WFacts_fun (Import E : DecidableType)(Import M : WSfun E).
 
 Notation eq_dec := E.eq_dec.
 Definition eqb x y := if eq_dec x y then true else false.
@@ -491,15 +489,14 @@ Qed.
 Add Morphism cardinal ; cardinal_m.
 *)
 
-End WFacts.
+End WFacts_fun.
 
+(** Now comes variants for self-contained weak sets and for full sets.
+    For these variants, only one argument is necessary. Thanks to
+    the subtyping [WS<=S], the [Facts] functor which is meant to be
+    used on modules [(M:S)] can simply be an alias of [WFacts]. *)
 
-(** Now comes a special version dedicated to full sets. For this 
-    one, only one argument [(M:S)] is necessary. *)
+Module WFacts (M:WS) := WFacts_fun M.E M.
+Module Facts := WFacts.
 
-Module Facts (Import M:S).
-  Module D:=OT_as_DT M.E.
-  Include WFacts D M.
-
-End Facts.