eqBox (Lam _ (x,t),s) (Lam _ (x',t'),s') =
      eq (x,Boxed (t,s)) (x',Boxed (t',s'))
eqBox (Lam _ (x,t),s) (Lam _ (x',t'),s') =
      eq (x,Boxed (t,s)) (x',Boxed (t',s'))
eqBox (Lam _ (x,t),s) (Lam _ (x',t'),s') =
      eq (x,Boxed (t,s)) (x',Boxed (t',s'))