replaced add_binds by singleton bind_term;

--- a/src/Pure/variable.ML	Sat Mar 28 16:00:54 2009 +0100
+++ b/src/Pure/variable.ML	Sat Mar 28 16:30:09 2009 +0100
@@ -30,7 +30,7 @@
   val declare_thm: thm -> Proof.context -> Proof.context
   val thm_context: thm -> Proof.context
   val variant_frees: Proof.context -> term list -> (string * 'a) list -> (string * 'a) list
-  val add_binds: (indexname * term option) list -> Proof.context -> Proof.context
+  val bind_term: indexname * term option -> Proof.context -> Proof.context
   val expand_binds: Proof.context -> term -> term
   val lookup_const: Proof.context -> string -> string option
   val is_const: Proof.context -> string -> bool
@@ -250,15 +250,13 @@
 
 (** term bindings **)
 
-fun add_bind (xi, NONE) = map_binds (Vartab.delete_safe xi)
-  | add_bind ((x, i), SOME t) =
+fun bind_term (xi, NONE) = map_binds (Vartab.delete_safe xi)
+  | bind_term ((x, i), SOME t) =
       let
         val u = Term.close_schematic_term t;
         val U = Term.fastype_of u;
       in declare_term u #> map_binds (Vartab.update ((x, i), (U, u))) end;
 
-val add_binds = fold add_bind;
-
 fun expand_binds ctxt =
   let
     val binds = binds_of ctxt;
@@ -486,7 +484,7 @@
     val all_vars = Thm.fold_terms Term.add_vars st [];
     val no_binds = map (fn (xi, _) => (xi, NONE)) all_vars;
   in
-    add_binds no_binds #>
+    fold bind_term no_binds #>
     fold (declare_constraints o Var) all_vars #>
     focus (Thm.cprem_of st i)
   end;