[commit: containers] master: Define Map.{union, difference, intersection}WithKey using mergeWithKey. (5810f06)

[Paolo Capriotti]

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

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/5810f064f1270688ebdcc7055545f3140f3aa5b2

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

commit 5810f064f1270688ebdcc7055545f3140f3aa5b2
Author: Milan Straka <fox at ucw.cz>
Date:   Sat Apr 28 16:36:31 2012 +0200

    Define Map.{union,difference,intersection}WithKey using mergeWithKey.
    
    The resulting implementations are approximately 40-50% faster, although
    for some input data the performance is worse. This happens
    * in unionWithKey, if the data are disjunct: 15% slowdown
    * in differenceWithKey, as now we recurse over the first tree and not
      the second. The slowdown happens also only for disjunct data: 30%.
    
    See the SetOperations benchmark for yourself if you are interested.

 Data/Map/Base.hs   |   84 ++--------------------------------------------------
 Data/Map/Strict.hs |   68 ++----------------------------------------
 2 files changed, 6 insertions(+), 146 deletions(-)


Diff suppressed because of size. To see it, use:

    git show 5810f064f1270688ebdcc7055545f3140f3aa5b2