patch applied (cabal-install): As a heuristic, use topological order for the order of package choices

[Duncan Coutts]

Fri May 30 11:44:37 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * As a heuristic, use topological order for the order of package choices
  The general case in exploring the state space is that we have a set of
  choices (package names) and for each choice we have a number of
  versions of that package we could pick. If there's only one version of
  a package then we make that choice first. Otherwise we have to pick
  some package and select one of the available versions. The question is
  which package should we make a choice for first? Previously we picked
  completely arbitrarily. Surprisingly this actually works pretty well.
  An improvement is to pick packages in topological order. This works
  better because it allows dependencies from earlier choices to
  constrain our later choices.

    M ./Hackage/Dependency/TopDown.hs -19 +86
    M ./Hackage/Dependency/TopDown/Types.hs -3 +17
    M ./cabal-install.cabal -1 +1

View patch online:
http://darcs.haskell.org/cabal-install/_darcs/patches/20080530184437-adfee-38542edbe3f8a0d34d062a31c85ad757d879a603.gz