I prefer pretty-show rather than groom as it's output is hierarchical.

http://hackage.haskell.org/package/pretty-show

Ozgur 

On 13 March 2012 22:37, Austin Seipp <mad.one@gmail.com> wrote:
It's not exactly hierarchical, but Groom most certainly should help
with getting much prettier output:

http://hackage.haskell.org/package/groom