It's a shame this doesn't just work out of the box in an xterm, on Debian at least. Perhaps we should consider switching to haskeline? Do we know anything about how portable and complete that is?
If a haskell-based solution could be made to work, that would be great - if you think that editline somehow less nice than readline, consider us poor windows users: we have neither!
Note that haskeline has a lot of dependencies and requires TemplateHaskell and many other language extensions.
Talking about dependencies of cabal packages: - some packages depend on everything and the kitchen-sink, following the "ah, great, here's another package I should use" idea of what it means to provide a modern haskell package. It would be nice if package authors would consider separate minimal and extended dependencies, the former sufficient to enable the package functionality, the latter enabled by a flag, and only needed for testing frameworks, parser re-generation, convenience, performance, .. - since Duncan has put in the work for making meta-packages possible for the Haskell Platform anyway, couldn't that be used to group typical dependencies together (eg, ghc corelibs, old extralibs, haskell platform, testing, ..), to make those dependency lists on hackage somewhat easier to comprehend? Probably, hackage/cabal could offer some support for reducing detailed dependencies to standard dependency groups. Claus