patch applied (cabal-install): Only inspect the needed parts of the installed and available indexes

[Duncan Coutts]

Sat Jun  7 07:39:13 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * Only inspect the needed parts of the installed and available indexes
  The available package index is loaded lazily so if we can avoid
  forcing all the packages then we can save a huge amount of slow text
  parsing. So select out the maximal subset of the index that we could
  ever need based on the names of the packages we want to install. For
  the common case of installing just one or two packages this cuts
  down the number of packages we look at by a couple orders of
  magnitude. This does not help with the installed index which is read
  strictly, though most people do not (yet) have hundreds of installed
  packages, so that's less of an immediate problem.

    M ./Hackage/Dependency/TopDown.hs -4 +42

View patch online:
http://darcs.haskell.org/cabal-install/_darcs/patches/20080607143913-adfee-df6d5af69a56190c82c4b1f14e30f752403043fc.gz