According to cabal, the following build dependencies for haskeline either aren't in Debian, or need to be updated to work with GHC 6.10:
extensible-exceptions-0.1.1.0 terminfo-0.3.0.1 -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org