SD4F: (exist? procedure-**maximum**-arity)

[Blake Shaw <blake@nonconstructivism.com>]

Hiya Guilers,

I've just started Sussman & Hanson's new book "Software Design for Flexibility" and am trying to translate one of the functions from MIT-Scheme to Guile:

#+BEGIN_SRC scheme
(define (get-arity proc)
  (or (hash-table-ref/default arity-table proc #f)
      (let ((a (procedure-arity proc))) ;arity not in table
        (assert (eqv? (procedure-arity-min a)
                      (procedure-arity-max a)))
        (procedure-arity-min a))))

(define arity-table (make-weak-key-hash-table))
#+END_SRC

So far this has lead me to these associations:
|------------------------------+--------------------------+-------------------------|
| MIT                          | Guile                    | Comments                |
|------------------------------+--------------------------+-------------------------|
| procedure-arity              | arity                    |                         |
|------------------------------+--------------------------+-------------------------|
| hash-table-set!              | hashq-set!               | possibly =hash-set!=    |
|------------------------------+--------------------------+-------------------------|
| hash-table-ref/default       | hashq-ref                | possibly =hash-ref=     |
|                              |                          | or =hash-get-handle=    |
|------------------------------+--------------------------+-------------------------|
| make-key-weak-eqv-hash-table | make-weak-key-hash-table | ∃(module) w/eqv-hash?   |
|                              |                          | think I saw it before   |
|------------------------------+--------------------------+-------------------------|
| assert                       | assert                   | in (rnrs base)          |
|                              | &assertion               | + (ice-9 exceptions)    |
|                              | assert-macro             | + in (debugging assert) |
|------------------------------+--------------------------+-------------------------|
| procedure-arity-min          | procedure-minimum-arity  |                         |

resulting in this translation of the function:

#+BEGIN_SRC scheme
 (define (get-arity proc)
    (or (hashq-ref arity-table proc #f)
	(let ((a (arity proc)))
	  (assert (eqv? (procedure-minimum-arity a)
			(**procedure-minimum-arity** a)))
	  (procedure-minimum-arity a))))
#+END_SRC 

So now I'm just left with figuring out a function for getting the **maximum**[1] arity of a procedure, but I'm unsure how to go about this.

I'm a sorta-new schemer and a very new guiler, so I'm unsure where to look... any advice would be appreciated![2]

Thanks & happy hacking,
Blake

[1] double earmuffs to emphasize its a function I need but dont have
[2] there is this inquiry already posted, but there was no conclusion https://mail.gnu.org/archive/html/guile-user/2021-05/msg00044.html 

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