+ match !proof,!goal with
+ None,_
+ | _,None -> assert false
+ | Some proof', Some goal' ->
+ let (newproof, newgoals) = tactic ~status:(proof', goal') in
+ proof := Some newproof;
+ goal :=
+ (match newgoals, newproof with
+ goal::_, _ -> Some goal
+ | [], (_,(goal,_,_)::_,_,_) ->
+ (* the tactic left no open goal ; let's choose the first open goal *)
+(*CSC: here we could implement and use a proof-tree like notion... *)
+ Some goal
+ | _, _ -> None)