with-only-class := λ(: tt Type). (: (
   (let rt TAny)
   (match tt (
      ()
      ( (TAnd( lt1 rt1 )) (
         (let lc (with-only-class lt1))
         (if (non-zero lc) (set rt lc) ())
         (let rc (with-only-class rt1))
         (if (non-zero rc) (set rt rc) ())
      ))
      ( (TGround( tag _ )) (
         (if (is-class tag) (
            (if (not(is-fragment tag)) (
               (set rt tt)
            ) ())
         ) ())
      ))
      ( _ () )
   ))
   rt
) Type);