patch applied (ghc): For single-method classes use newtypes

[Simon Peyton Jones]

Mon Nov  1 01:07:36 PDT 2010  simonpj at microsoft.com
  * For single-method classes use newtypes
  
  This clears up an awkward hack for exprIsConApp_maybe, and
  works better too.  See Note [Single-method classes] in
  TcInstDcls.

    M! ./compiler/basicTypes/MkId.lhs -7 +9
    M! ./compiler/deSugar/DsBinds.lhs -2 +1
    M! ./compiler/typecheck/TcInstDcls.lhs -42 +84

View patch online:
http://darcs.haskell.org/cgi-bin/darcsweb.cgi?r=ghc;a=darcs_commitdiff;h=20101101080736-1287e-85e451ba64fae4824f39e3a8096f1632f7c9e8a2.gz