[Haskell-cafe] exists . a psuedo-standard non-empty list module

I don't particularly like using fromJust or head, and there's been plenty of discussion on those issues. For the cases where it makes good sense to do so, I'm about to write a module for non-empty lists that looks to strike a balance between usability and static checks. But before I re-invent the wheel, I was wondering if there's already a popular module along those lines. I would also appreciate references to your favorite discussion about uses of head and other unsafe functions or various Oleg posts showing how they're all unnecessary. I'll find these on my own, but I would also like to know which ones strike a chord with the community. Thanks for your time. -Nick