Downloading a file from a URL from the web with http-get

[白熊]

Hello everybody:

I'm learning Guile. I'd like to write a utility, which will enable me upon user 
input download program sources from the web, i.e. not a web-spider, but 
download discrete URL's and save them to disk.

I've looked at:

http://lists.gnu.org/archive/html/guile-user/2012-04/msg00032.html
http://lists.gnu.org/archive/html/guile-user/2012-05/msg00005.html

so the possibility to do, seems to be there.

Specifically, let's say, I want to download:

http://ftp.gnu.org/pub/gnu/guile/guile-2.0.11.tar.xz

and save it to ~/

How should I modify the following code to do this?:

(use-modules ((web uri)    #:select (string->uri))
               ((web client) #:select (http-get)))
  (call-with-values (lambda ()
                      (http-get
                       (string->uri "http://www.gnu.org/software/guile/";)))
    (lambda (res-headers res-body)
      (display res-body)
      (newline)))

i.e. not display the body, but save it to file? Or is the above only applicable 
to text responses - webpages, and not for binary files?

Thanks very much for any help.
--
白熊