(define quoted
  (sequence* ((_ (is #\'))
              (expr patom))
             (λ (x)
               (result (list 'quoted x)))))

(define patom
  (bind (as-string (one-or-more not-whitespace))
        (λ (x)
          (result (list 'atom x)))))



Gives:

Error: (car) bad argument type: #<procedure>

   Call history:

   <syntax>   (parse parse-expr "'test")
   <eval>     (parse parse-expr "'test")
   <eval>     (bind1000 patom (lambda1001 (expr) (sequence*1002 () (lambda (x) (result (list (quote quoted) x)))))...
   <eval>     (result (list (quote atom) x))
   <eval>     (list (quote atom) x)
   <eval>     (result (list (quote quoted) x))
   <eval>     (list (quote quoted) x)  <--