patch applied (packages/base): add Applicative instance for Either (proposal #4095)

[Ross Paterson]

Thu Jun 17 15:51:10 PDT 2010  Ross Paterson <ross at soi.city.ac.uk>
  * add Applicative instance for Either (proposal #4095)
  
  This is not the only possible instance for Either, but this one is
  compatible with the usual Monad instance.

    M ./Control/Applicative.hs +5

View patch online:
http://darcs.haskell.org/cgi-bin/darcsweb.cgi?r=packages/base;a=darcs_commitdiff;h=20100617225110-b47d3-f6fc17fd65ac284f7adc3a2ea100304ad4b3c2b8.gz