[web-devel] [Yesod] How to write approot to handle http and https.

Hi I'd like to host application for http and https. I set up apache and use rewrite rules. In this case, how do i write approot of Yesod instance? when client request by http://www.foo.com/a/b/c/, approot must be http://www.foo.com, one the other hand, when client request by https://www.foo.com/a/b/c/, approot must be https://www.foo.com. how do i write?