[Xmonad] xmonad is a zipper

[Donald Bruce Stewart]

ndmitchell:
> Hi
> 
> >> * new relies on the Integral type having sensible semantics, if you
> >> pass Int or Integer its fine (machine checked), but if you create a
> >> crazy type, make it an instance of Integral then [0..n-1] may generate
> >> no elements, and your (h:t) match will fail.
> >
> >Tricky.
> 
> You can fix this with:
> 
>    where (h:ts) = Workspace 0 Empty : [ Workspace i Empty | i <- [1 ..n-1]]
 
Yep. I was referring more to the fact that funny instances can lead to
funny enumFromTos. instances can be evil!

-- Don