patch applied (packages/base): Make intersectBy lazier

[Ian Lynagh]

Thu Sep 30 12:17:31 PDT 2010  Daniel Fischer <daniel.is.fischer at web.de>
  * Make intersectBy lazier
  Add shortcuts to intersectBy for empty list arguments.
  In addition to being faster in that case, more inputs yield defined results.
  Treats ticket #4323

    M ./Data/List.hs +2

View patch online:
http://darcs.haskell.org/cgi-bin/darcsweb.cgi?r=packages/base;a=darcs_commitdiff;h=20100930191731-a0d69-78d979be7731b67754bf21bcf39b081dca99a6cb.gz