patch applied (ghc): Add support for overloaded string literals.

Thu Dec 21 13:01:47 PST 2006  [email protected]
  * Add support for overloaded string literals.
  
  The class is named IsString with the single method fromString.
  Overloaded strings work the same way as overloaded numeric literals.
  In expressions a string literals gets a fromString applied to it.
  In a pattern there will be an equality comparison with the fromString:ed literal.
  
  Use -foverloaded-strings to enable this extension.
   

    M ./compiler/deSugar/Check.lhs +1
    M ./compiler/deSugar/DsExpr.lhs -1 +1
    M ./compiler/deSugar/DsMeta.hs +3
    M ./compiler/deSugar/MatchLit.lhs +9
    M ./compiler/hsSyn/Convert.lhs +1
    M ./compiler/hsSyn/HsLit.lhs +8
    M ./compiler/hsSyn/HsUtils.lhs +1
    M ./compiler/main/DynFlags.hs +2
    M ./compiler/parser/Parser.y.pp -1 +4
    M ./compiler/parser/RdrHsSyn.lhs -1 +1
    M ./compiler/prelude/PrelNames.lhs -4 +22
    M ./compiler/rename/RnEnv.lhs -1 +1
    M ./compiler/rename/RnExpr.lhs +10
    M ./compiler/rename/RnTypes.lhs -2 +10
    M ./compiler/typecheck/Inst.lhs -1 +26
    M ./compiler/typecheck/TcDefaults.lhs +1
    M ./compiler/typecheck/TcHsSyn.lhs +2
    M ./compiler/typecheck/TcPat.lhs +13
    M ./compiler/typecheck/TcSimplify.lhs -3 +8