gistfile1.txt

(define-method object-apply ((operand <top>) arg . args)
  (let* ([args (cons arg args)]
         [operator (find (^a (or (is-a? a <procedure>)
                                 (is-a? a <generic>)))
                         args)]
         [operands (map (^a (if (is-a? a <kwoted>)
                              (~ a'fn)
                              a))
                        (cons operand (delete operator args)))])
    (unless operator
      (error "No operator in application form:" (cons operand args)))
    (apply operator operands)))

(define-class <kwoted> ()
  ((fn :init-keyword :fn)))
(define (& fn) (make <kwoted> :fn fn))

#|
gosh> ((& number?) ("abc" 123 "def" list) find)
123
gosh> (define (sagasu lis fn) ((& fn) find lis))
sagasu
gosh> (("abc" 123 "def" list) sagasu (& number?))
123
|#