patch applied (cabal-install): First version of the top-down package dependency resolver

[Duncan Coutts]

Wed May 28 14:58:04 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * First version of the top-down package dependency resolver
  This is a new dependency resolver that produces valid install plans.
  It works in polynomial time however because the search space is 
  exponential in size it is not guaranteed to find a solution even if
  one exists. It works by generating and then exploring the search
  space represented as a lazy tree. It uses constraints to prune
  choices and heuristics when guesses are necessary. Currently it can
  generate install plans for 99% of the packages on hackage. The
  remaining 6 packages should be doable with two extra tricks.
  It is not finished and is not yet usable in practice.

    M ./Hackage/Dependency.hs +2
    A ./Hackage/Dependency/TopDown/
    A ./Hackage/Dependency/TopDown.hs
    A ./Hackage/Dependency/TopDown/Constraints.hs
    A ./Hackage/Dependency/TopDown/Types.hs
    M ./Hackage/Dependency/Types.hs +27
    M ./cabal-install.cabal -1 +4

View patch online:
http://darcs.haskell.org/cabal-install/_darcs/patches/20080528215804-adfee-26201449f6c9f7e428871ccb592ed1c52d92805f.gz