--- a/src/HOL/Tools/Function/relation.ML Tue May 04 10:02:43 2010 +0200
+++ b/src/HOL/Tools/Function/relation.ML Tue May 04 10:49:46 2010 +0200
@@ -14,19 +14,20 @@
structure Function_Relation : FUNCTION_RELATION =
struct
-fun inst_thm ctxt rel st =
+fun inst_state_tac ctxt rel st =
let
val cert = Thm.cterm_of (ProofContext.theory_of ctxt)
val rel' = cert (singleton (Variable.polymorphic ctxt) rel)
val st' = Thm.incr_indexes (#maxidx (Thm.rep_cterm rel') + 1) st
- val Rvar = cert (Var (the_single (Term.add_vars (prop_of st') [])))
- in
- Drule.cterm_instantiate [(Rvar, rel')] st'
+ in case Term.add_vars (prop_of st') [] of
+ [v] =>
+ PRIMITIVE (Drule.cterm_instantiate [(cert (Var v), rel')]) st'
+ | _ => Seq.empty
end
fun relation_tac ctxt rel i =
TRY (Function_Common.apply_termination_rule ctxt i)
- THEN PRIMITIVE (inst_thm ctxt rel)
+ THEN inst_state_tac ctxt rel
val setup =
Method.setup @{binding relation}