[plt-scheme] #:log-format 'parenthesized-default

Hi,
I think I'm missing a trick:

I'm using serve/servlet with
 #:log-file (build-path  (current-directory) (string->path
(string-append "thread-" (get-date))))
and  #:log-format 'parenthesized-default
but it brings up an error 'does not expect an argument with keyword
#:log-format'

This seems odd, as excluding the argument returns the error
'application: missing argument expression after keyword in:
#:log-format'

* Adding a require for web-server/dispatchers/dispatch-log seemed to
have no effect.
* I believe the argument is correct as per
http://docs.plt-scheme.org/web-server/servlet-env_ss.html

I think I've probably missed something simple - any suggestions?

Thanks,

Stephen

-a working example-

#lang scheme
(require  web-server/servlet
          web-server/templates
          web-server/dispatchers/dispatch-log
          scheme/date
          )
(provide/contract (start (request? . -> . response?)))

(define (logfile-path)
  (build-path  (current-directory) (string->path (string-append "thread-"

(number->string (date-year (seconds->date (current-seconds)))) "-"

(number->string (date-month (seconds->date (current-seconds)))) "-"

(number->string (date-day (seconds->date (current-seconds)))) "_"

(number->string (date-hour (seconds->date (current-seconds)))) "-"

(number->string (date-minute (seconds->date (current-seconds)))) "-"

(number->string (date-second (seconds->date (current-seconds))))
".log"

                                                                ))))


  (define (start request)
    `(html (head (title "Hello world!"))
           (body (p "Hey out there!"))))



  (require web-server/servlet-env)
  (serve/servlet start
                 #:launch-browser? #t
                 #:quit? #f
                 #:listen-ip #f
                 #:port 8000
                 #:extra-files-paths
                 (list (current-directory))
                 #:servlet-path "/threads-vi.ss"
                 #:mime-types-path "data/mime.types"
                 #:log-file (logfile-path)
                 #:log-format 'parenthesized-default
                 )

  ;---


-MY code-
#lang scheme
;#lang web-server/insta
(require  web-server/servlet
          web-server/templates
          web-server/dispatchers/dispatch-log
          scheme/gui ;
          xml
          net/sendurl
          scheme/date
          "standard-requires.ss"
          )
(provide/contract (start (request? . -> . response?)))
[...]
(require web-server/servlet-env)
(serve/servlet start
               #:launch-browser? #t
               #:quit? #f
               #:listen-ip #f
               #:port 8000
               #:extra-files-paths
               (list (current-directory))
               #:servlet-path "/threads-vi.ss"
               #:mime-types-path "data/mime.types"
               #:log-file (build-path  (current-directory)
(string->path (string-append "thread-" (get-date))))
               #:log-format 'parenthesized-default
               )

-