diff options
Diffstat (limited to 'theories/FSets/OrderedTypeAlt.v')
| -rw-r--r-- | theories/FSets/OrderedTypeAlt.v | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/theories/FSets/OrderedTypeAlt.v b/theories/FSets/OrderedTypeAlt.v index 516df0f0..9d179995 100644 --- a/theories/FSets/OrderedTypeAlt.v +++ b/theories/FSets/OrderedTypeAlt.v @@ -11,11 +11,12 @@ * Institution: LRI, CNRS UMR 8623 - Université Paris Sud * 91405 Orsay, France *) -(* $Id: OrderedTypeAlt.v 10739 2008-04-01 14:45:20Z herbelin $ *) +(* $Id: OrderedTypeAlt.v 11699 2008-12-18 11:49:08Z letouzey $ *) Require Import OrderedType. -(** * An alternative (but equivalent) presentation for an Ordered Type inferface. *) +(** * An alternative (but equivalent) presentation for an Ordered Type + inferface. *) (** NB: [comparison], defined in [Datatypes.v] is [Eq|Lt|Gt] whereas [compare], defined in [OrderedType.v] is [EQ _ | LT _ | GT _ ] @@ -81,6 +82,12 @@ Module OrderedType_from_Alt (O:OrderedTypeAlt) <: OrderedType. rewrite compare_sym; rewrite H; auto. Defined. + Definition eq_dec : forall x y, { eq x y } + { ~ eq x y }. + Proof. + intros; unfold eq. + case (x ?= y); [ left | right | right ]; auto; discriminate. + Defined. + End OrderedType_from_Alt. (** From the original presentation to this alternative one. *) |