[commit: Cabal] master: switch to less precise, more efficient goal reordering (92a4214)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/Cabal

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/92a4214f5345d09e67e3725fe3a6167b49dc2a66

>---------------------------------------------------------------

commit 92a4214f5345d09e67e3725fe3a6167b49dc2a66
Author: Andres Loeh <andres at well-typed.com>
Date:   Sun Jul 3 13:43:59 2011 +0000

    switch to less precise, more efficient goal reordering

>---------------------------------------------------------------

 .../Client/Dependency/Modular/Dependency.hs        |    6 +++---
 .../Client/Dependency/Modular/Solver.hs            |    2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/cabal-install/Distribution/Client/Dependency/Modular/Dependency.hs b/cabal-install/Distribution/Client/Dependency/Modular/Dependency.hs
index 17a36d0..78c1d4f 100644
--- a/cabal-install/Distribution/Client/Dependency/Modular/Dependency.hs
+++ b/cabal-install/Distribution/Client/Dependency/Modular/Dependency.hs
@@ -74,9 +74,9 @@ showCI (Constrained vr) = showVR (collapse vr)
 -- order in which we check the constraints.
 merge :: Ord qpn => CI qpn -> CI qpn -> Either (ConflictSet qpn, (CI qpn, CI qpn)) (CI qpn)
 merge c@(Fixed i g1)       d@(Fixed j g2)
-  | i == j                                   = Right c
-  | otherwise                                = Left (S.union (toConflictSet g1) (toConflictSet g2), (c, d))
-merge c@(Fixed (I v _) g1)   (Constrained rs) = go rs
+  | i == j                                    = Right c
+  | otherwise                                 = Left (S.union (toConflictSet g1) (toConflictSet g2), (c, d))
+merge c@(Fixed (I v _) g1)   (Constrained rs) = go rs -- I tried "reverse rs" here, but it seems to slow things down ...
   where
     go []              = Right c
     go (d@(vr, g2) : vrs)
diff --git a/cabal-install/Distribution/Client/Dependency/Modular/Solver.hs b/cabal-install/Distribution/Client/Dependency/Modular/Solver.hs
index 0c2b1b6..24a4e59 100644
--- a/cabal-install/Distribution/Client/Dependency/Modular/Solver.hs
+++ b/cabal-install/Distribution/Client/Dependency/Modular/Solver.hs
@@ -46,7 +46,7 @@ solve sc idx userPrefs userConstraints userGoals =
   where
     explorePhase = exploreTreeLog . backjump
     heuristicsPhase = if preferEasyGoalChoices sc
-                        then P.deferDefaultFlagChoices . P.preferEasyGoalChoices
+                        then P.deferDefaultFlagChoices . P.lpreferEasyGoalChoices
                         else id
     preferencesPhase = P.preferPackagePreferences userPrefs
     validationPhase = P.enforcePackageConstraints userConstraints .