Byrd's box never left the ground

agg_all_(min(X,W), Goal, min(Min,Witness)) :-
  State = state(X,W),
  (  call(Goal),
   (
    (nb_setarg(1, State, X),
     nb_setarg(2, State, W),
     fail)
  ;
    (arg(1, State, M0),
     X @< M0,
     nb_setarg(1, State, X),
     nb_setarg(2, State, W),
     fail)
  )
  ;
     arg(1, State, Min),
     arg(2, State, Witness),
     nonvar(Min),
     nonvar(Witness)
  ).