Hi,

On 25 April 2012 16:36, Michael Snoyman <michael@snoyman.com> wrote:

Prelude.head: empty list

Recent versions of GHC actually generate a very helpful stack trace, if the program is compiled with profiling turned on and run with -xc.

See: http://community.haskell.org/~simonmar/slides/HIW11.pdf (Ironically titled "Prelude.head: empty list")

HTH,