[web-devel] Getting the http request header in Yesod?

[Rehno Lindeque]

I'm looking to detect ajax requests sent to my yesod application using
the technique detailed in http://davidwalsh.name/detect-ajax

Is it possible to gain access to the request header directly or would
yesod require modification to get at it? If someone could just point
me in the right direction, I would be grateful. I imagine it would be
a function returning GHandler?

Thanks,
Rehno