SaitoAtsushi

(define-syntax let-optionals
  (syntax-rules ()
    ((_ args ((var default) rest ... . restarg) body ...)
     (let* ((tmp args)
            (var (if (null? tmp) default (car tmp))))
       (let-optionals (if (null? tmp) '() (cdr tmp))
                      (rest ... . restarg)
                      body ...)))
    ((_ args () body ...)
     (begin body ...))