where to catch handler exception

[CCH C]

Hi, I am using auth snaplet, where shall I catch the duplicateLogin exception or any other exception. I don't want to let the app respond with a "web handler exception" text. I read the Control.Exception docs, and find that `catch` can only be used in IO monad. How can I `catch` in MandSnap?

Thanks 

[MightyByte]

If you look at the documentation for the Handler monad, you'll see
that it is an instance of MonadCatchIO.

http://hackage.haskell.org/packages/archive/snap/0.8.0.2/doc/html/Snap-Snaplet.html#t:Handler

If you click on that instance, you'll see the exception handling
functions you're looking for.

http://hackage.haskell.org/packages/archive/MonadCatchIO-transformers/0.2.2.3/doc/html/Control-Monad-CatchIO.html#t:MonadCatchIO

[CCH C]

Now I see. Thank you so much!