Pprint with-float-traps-masked better

Describe the feature

Cmucl pprints the form

(with-float-traps-masked (:underflow)
  (let* ((ratio (/ (* (expt 10 exponent) number)
                   divisor))
	 (result (coerce ratio float-format)))
    (when (and (zerop result) (not (zerop number)))
      ;; The number we've read is so small that it gets
      ;; converted to 0.0, but is not actually zero.  Signal an
      ;; error.  See CLHS 2.3.1.1.
      (error _"Underflow"))
    result))

as

* (pprint '(with-float-traps-masked (:underflow)
  (let* ((ratio (/ (* (expt 10 exponent) number)
                   divisor))
	 (result (coerce ratio float-format)))
    (when (and (zerop result) (not (zerop number)))
      ;; The number we've read is so small that it gets
      ;; converted to 0.0, but is not actually zero.  Signal an
      ;; error.  See CLHS 2.3.1.1.
      (error "Underflow"))
    result)))


(WITH-FLOAT-TRAPS-MASKED (:UNDERFLOW)
                         (LET* ((RATIO
                                 (/ (* (EXPT 10 EXPONENT) NUMBER) DIVISOR))
                                (RESULT (COERCE RATIO FLOAT-FORMAT)))
                           (WHEN (AND (ZEROP RESULT) (NOT (ZEROP NUMBER)))
                             (ERROR "Underflow"))
                           RESULT))

This looks funny.

Is there a prototype?

No prototype, but shouldn't be too hard to make it work by adding a new pprinter to pprint.lisp. We should do the same formatting for with-float-traps-enabled too.