Changes to ghc

Changes to ghc:
commit 7a15a68d08cde4d8b5b4e53f0c887aeeae233536
Author: Edward Z. Yang <ezyang@cs.stanford.edu>
Date:   Wed Jul 9 09:40:42 2014 +0100

    Scott's updates to the impl paper.

    Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>