Thank you Linus, On Sun, Feb 5, 2012 at 7:00 PM, Linus Arver wrote:

You should separate out the pure computations out of your managehook stuff and then use QuickCheck on those functions. A zero-division error sounds like it's from your own code (if not, then you should contact the maintainer(s) of the libraries in question and send a bug report).

I'd like to see the example of separating "the pure computations out of your managehook stuff and then use QuickCheck on those functions". But I suppose it is possible to test the manage hook as is (w/o separating the pure computation part), or it is not? And yes, the zero-division error is in my management hook. I want to learn Haskell and XMonad is interesting project. That's why I tried to start it by hacking XMonad after quickly reading some Haskell web book.

Thanks! I had a look at it but since it does not import ManageHook I did not read it seriously. I will try it again.

On Mon, Feb 06, 2012 at 12:14:18PM +0100, Takafumi Arakaki wrote:

Thank you Linus,

On Sun, Feb 5, 2012 at 7:00 PM, Linus Arver wrote:

...

You should separate out the pure computations out of your managehook stuff and then use QuickCheck on those functions. A zero-division error sounds like it's from your own code (if not, then you should contact the maintainer(s) of the libraries in question and send a bug report).

I'd like to see the example of separating "the pure computations out of your managehook stuff and then use QuickCheck on those functions". But I suppose it is possible to test the manage hook as is (w/o separating the pure computation part), or it is not? And yes, the zero-division error is in my management hook.

What I meant was, just test the pure (monad-free) code that you added on your own in your managemenet hook stuff. I.e., you should refactor your functions so that the pure parts are separate on their own, and then test these smaller (pure) functions. Here's a tutorial on how to do this: http://www.haskell.org/haskellwiki/Introduction_to_QuickCheck. The "getList" function's type signature there is "IO String", and the tutorial goes on about how to test the pure, smaller parts outside of the IO monad. Testing the manage hook "as is" w/o separating the pure computation part is probably really hard to do... if I'm not mistaken XMonad already uses QuickCheck so you'd have to dig inside the XMonad code for some examples. This is a lot more difficult than just testing pure parts... You could post your managment hook code on this list or the Haskell Beginner's list [1] for more specific pointers. [1] http://www.haskell.org/mailman/listinfo/beginners -Linus