content: {-
  (c) The University of Glasgow 2006
  (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
  -}
  
  {-# LANGUAGE DeriveDataTypeable, BangPatterns #-}
  
  -- |
  -- #name_types#
  -- GHC uses several kinds of name internally:
  --
  -- * 'OccName.OccName' represents names as strings with just a little more information:
  --   the \"namespace\" that the name came from, e.g. the namespace of value, type constructors or
  --   data constructors
  --
  -- * 'RdrName.RdrName': see "RdrName#name_types"
  --
  -- * 'Name.Name': see "Name#name_types"
  --
  -- * 'Id.Id': see "Id#name_types"
  --
  -- * 'Var.Var': see "Var#name_types"
  
  module Eta.BasicTypes.OccName (
          -- * The 'NameSpace' type
          NameSpace, -- Abstract
  
          nameSpacesRelated,
  
          -- ** Construction
          -- $real_vs_source_data_constructors
          tcName, clsName, tcClsName, dataName, varName,
          tvName, srcDataName,
  
          -- ** Pretty Printing
          pprNameSpace, pprNonVarNameSpace, pprNameSpaceBrief,
  
          -- * The 'OccName' type
          OccName,        -- Abstract, instance of Outputable
          pprOccName,
  
          -- ** Construction
          mkOccName, mkOccNameFS,
          mkVarOcc, mkVarOccFS,
          mkDataOcc, mkDataOccFS,
          mkTyVarOcc, mkTyVarOccFS,
          mkTcOcc, mkTcOccFS,
          mkClsOcc, mkClsOccFS,
          mkDFunOcc,
          setOccNameSpace,
          demoteOccName,
          HasOccName(..),
  
          -- ** Derived 'OccName's
          isDerivedOccName,
          mkDataConWrapperOcc, mkWorkerOcc,
          mkMatcherOcc, mkBuilderOcc,
          mkDefaultMethodOcc,
          mkGenDefMethodOcc,
          mkDerivedTyConOcc, mkNewTyCoOcc, mkClassOpAuxOcc,
          mkCon2TagOcc, mkTag2ConOcc, mkMaxTagOcc,
          mkClassDataConOcc, mkDictOcc, mkIPOcc,
          mkSpecOcc, mkForeignExportOcc, mkRepEqOcc, mkGenOcc1, mkGenOcc2,
          mkGenD, mkGenR, mkGen1R, mkGenRCo, mkGenC, mkGenS,
          mkDataTOcc, mkDataCOcc, mkDataConWorkerOcc,
          mkSuperDictSelOcc, mkLocalOcc, mkLocalOccWithoutUnique, mkMethodOcc, mkInstTyTcOcc,
          mkInstTyCoOcc, mkEqPredCoOcc,
          mkVectOcc, mkVectTyConOcc, mkVectDataConOcc, mkVectIsoOcc,
          mkPDataTyConOcc,  mkPDataDataConOcc,
          mkPDatasTyConOcc, mkPDatasDataConOcc,
          mkPReprTyConOcc,
          mkPADFunOcc,
          mkJavaImportOcc,
  
          -- ** Deconstruction
          occNameFS, occNameString, occNameSpace,
  
          isVarOcc, isTvOcc, isTcOcc, isDataOcc, isDataSymOcc, isSymOcc, isValOcc,
          parenSymOcc, startsWithUnderscore,
  
          isTcClsNameSpace, isTvNameSpace, isDataConNameSpace, isVarNameSpace, isValNameSpace,
  
          -- * The 'OccEnv' type
          OccEnv, emptyOccEnv, unitOccEnv, extendOccEnv, mapOccEnv,
          lookupOccEnv, mkOccEnv, mkOccEnv_C, extendOccEnvList, elemOccEnv,
          occEnvElts, foldOccEnv, plusOccEnv, plusOccEnv_C, extendOccEnv_C,
          extendOccEnv_Acc, filterOccEnv, delListFromOccEnv, delFromOccEnv,
          alterOccEnv, pprOccEnv,
  
          -- * The 'OccSet' type
          OccSet, emptyOccSet, unitOccSet, mkOccSet, extendOccSet,
          extendOccSetList,
          unionOccSets, unionManyOccSets, minusOccSet, elemOccSet,
          isEmptyOccSet, intersectOccSet, intersectsOccSet,
  
          -- * Tidying up
          TidyOccEnv, emptyTidyOccEnv, tidyOccName, initTidyOccEnv,
  
          -- FsEnv
          FastStringEnv, emptyFsEnv, lookupFsEnv, extendFsEnv, extendFsEnvWith, mkFsEnv
      ) where
  
  import Eta.Utils.Util
  import Eta.BasicTypes.Unique
  import Eta.Main.DynFlags
  import Eta.Utils.UniqFM
  import Eta.Utils.UniqSet
  import Eta.Utils.FastString
  import Eta.Utils.Outputable
  import Eta.BasicTypes.Lexeme
  import Eta.Utils.Binary
  import Data.Char
  import Data.Data
  
  {-
  ************************************************************************
  *                                                                      *
                FastStringEnv
  *                                                                      *
  ************************************************************************
  
  FastStringEnv can't be in FastString because the env depends on UniqFM
  -}
  
  type FastStringEnv a = UniqFM a         -- Keyed by FastString
  
  
  emptyFsEnv      :: FastStringEnv a
  lookupFsEnv     :: FastStringEnv a  -> FastString -> Maybe a
  extendFsEnv     :: FastStringEnv a  -> FastString -> a -> FastStringEnv a
  extendFsEnvWith :: FastStringEnv a  -> [(FastString, a)] -> FastStringEnv a
  mkFsEnv         :: [(FastString,a)] -> FastStringEnv a
  
  emptyFsEnv      = emptyUFM
  lookupFsEnv     = lookupUFM
  extendFsEnv     = addToUFM
  extendFsEnvWith = addListToUFM
  mkFsEnv         = listToUFM
  
  {-
  ************************************************************************
  *                                                                      *
  \subsection{Name space}
  *                                                                      *
  ************************************************************************
  -}
  
  data NameSpace = VarName        -- Variables, including "real" data constructors
                 | DataName       -- "Source" data constructors
                 | TvName         -- Type variables
                 | TcClsName      -- Type constructors and classes; Haskell has them
                                  -- in the same name space for now.
                 deriving( Eq, Ord )
     {-! derive: Binary !-}
  
  -- Note [Data Constructors]
  -- see also: Note [Data Constructor Naming] in DataCon.lhs
  --
  -- $real_vs_source_data_constructors
  -- There are two forms of data constructor:
  --
  --      [Source data constructors] The data constructors mentioned in Haskell source code
  --
  --      [Real data constructors] The data constructors of the representation type, which may not be the same as the source type
  --
  -- For example:
  --
  -- > data T = T !(Int, Int)
  --
  -- The source datacon has type @(Int, Int) -> T@
  -- The real   datacon has type @Int -> Int -> T@
  --
  -- GHC chooses a representation based on the strictness etc.
  
  tcName, clsName, tcClsName :: NameSpace
  dataName, srcDataName      :: NameSpace
  tvName, varName            :: NameSpace
  
  -- Though type constructors and classes are in the same name space now,
  -- the NameSpace type is abstract, so we can easily separate them later
  tcName    = TcClsName           -- Type constructors
  clsName   = TcClsName           -- Classes
  tcClsName = TcClsName           -- Not sure which!
  
  dataName    = DataName
  srcDataName = DataName  -- Haskell-source data constructors should be
                          -- in the Data name space
  
  tvName      = TvName
  varName     = VarName
  
  isDataConNameSpace :: NameSpace -> Bool
  isDataConNameSpace DataName = True
  isDataConNameSpace _        = False
  
  isTcClsNameSpace :: NameSpace -> Bool
  isTcClsNameSpace TcClsName = True
  isTcClsNameSpace _         = False
  
  isTvNameSpace :: NameSpace -> Bool
  isTvNameSpace TvName = True
  isTvNameSpace _      = False
  
  isVarNameSpace :: NameSpace -> Bool     -- Variables or type variables, but not constructors
  isVarNameSpace TvName  = True
  isVarNameSpace VarName = True
  isVarNameSpace _       = False
  
  isValNameSpace :: NameSpace -> Bool
  isValNameSpace DataName = True
  isValNameSpace VarName  = True
  isValNameSpace _        = False
  
  pprNameSpace :: NameSpace -> SDoc
  pprNameSpace DataName  = ptext (sLit "data constructor")
  pprNameSpace VarName   = ptext (sLit "variable")
  pprNameSpace TvName    = ptext (sLit "type variable")
  pprNameSpace TcClsName = ptext (sLit "type constructor or class")
  
  pprNonVarNameSpace :: NameSpace -> SDoc
  pprNonVarNameSpace VarName = empty
  pprNonVarNameSpace ns = pprNameSpace ns
  
  pprNameSpaceBrief :: NameSpace -> SDoc
  pprNameSpaceBrief DataName  = char 'd'
  pprNameSpaceBrief VarName   = char 'v'
  pprNameSpaceBrief TvName    = ptext (sLit "tv")
  pprNameSpaceBrief TcClsName = ptext (sLit "tc")
  
  -- demoteNameSpace lowers the NameSpace if possible.  We can not know
  -- in advance, since a TvName can appear in an HsTyVar.
  -- See Note [Demotion] in RnEnv
  demoteNameSpace :: NameSpace -> Maybe NameSpace
  demoteNameSpace VarName = Nothing
  demoteNameSpace DataName = Nothing
  demoteNameSpace TvName = Nothing
  demoteNameSpace TcClsName = Just DataName
  
  {-
  ************************************************************************
  *                                                                      *
  \subsection[Name-pieces-datatypes]{The @OccName@ datatypes}
  *                                                                      *
  ************************************************************************
  -}
  
  data OccName = OccName
      { occNameSpace  :: !NameSpace
      , occNameFS     :: !FastString
      }
      deriving Typeable
  
  instance Eq OccName where
      (OccName sp1 s1) == (OccName sp2 s2) = s1 == s2 && sp1 == sp2
  
  instance Ord OccName where
          -- Compares lexicographically, *not* by Unique of the string
      compare (OccName sp1 s1) (OccName sp2 s2)
          = (s1  `compare` s2) `thenCmp` (sp1 `compare` sp2)
  
  instance Data OccName where
    -- don't traverse?
    toConstr _   = abstractConstr "OccName"
    gunfold _ _  = error "gunfold"
    dataTypeOf _ = mkNoRepType "OccName"
  
  instance HasOccName OccName where
    occName = id
  
  {-
  ************************************************************************
  *                                                                      *
  \subsection{Printing}
  *                                                                      *
  ************************************************************************
  -}
  
  instance Outputable OccName where
      ppr = pprOccName
  
  instance OutputableBndr OccName where
      pprBndr _ = ppr
      pprInfixOcc n = pprInfixVar (isSymOcc n) (ppr n)
      pprPrefixOcc n = pprPrefixVar (isSymOcc n) (ppr n)
  
  pprOccName :: OccName -> SDoc
  pprOccName (OccName sp occ)
    = getPprStyle $ \ sty ->
      if codeStyle sty
      then ztext (zEncodeFS occ)
      else pp_occ <> pp_debug sty
    where
      pp_debug sty | debugStyle sty = braces (pprNameSpaceBrief sp)
                   | otherwise      = empty
  
      pp_occ = sdocWithDynFlags $ \dflags ->
               if gopt Opt_SuppressUniques dflags
               then text (strip_th_unique (unpackFS occ))
               else ftext occ
  
          -- See Note [Suppressing uniques in OccNames]
      strip_th_unique ('[' : c : _) | isAlphaNum c = []
      strip_th_unique (c : cs) = c : strip_th_unique cs
      strip_th_unique []       = []
  
  {-
  Note [Suppressing uniques in OccNames]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  This is a hack to de-wobblify the OccNames that contain uniques from
  Template Haskell that have been turned into a string in the OccName.
  See Note [Unique OccNames from Template Haskell] in Convert.hs
  
  ************************************************************************
  *                                                                      *
  \subsection{Construction}
  *                                                                      *
  ************************************************************************
  -}
  
  mkOccName :: NameSpace -> String -> OccName
  mkOccName occ_sp str = OccName occ_sp (mkFastString str)
  
  mkOccNameFS :: NameSpace -> FastString -> OccName
  mkOccNameFS occ_sp fs = OccName occ_sp fs
  
  mkVarOcc :: String -> OccName
  mkVarOcc s = mkOccName varName s
  
  mkVarOccFS :: FastString -> OccName
  mkVarOccFS fs = mkOccNameFS varName fs
  
  mkDataOcc :: String -> OccName
  mkDataOcc = mkOccName dataName
  
  mkDataOccFS :: FastString -> OccName
  mkDataOccFS = mkOccNameFS dataName
  
  mkTyVarOcc :: String -> OccName
  mkTyVarOcc = mkOccName tvName
  
  mkTyVarOccFS :: FastString -> OccName
  mkTyVarOccFS fs = mkOccNameFS tvName fs
  
  mkTcOcc :: String -> OccName
  mkTcOcc = mkOccName tcName
  
  mkTcOccFS :: FastString -> OccName
  mkTcOccFS = mkOccNameFS tcName
  
  mkClsOcc :: String -> OccName
  mkClsOcc = mkOccName clsName
  
  mkClsOccFS :: FastString -> OccName
  mkClsOccFS = mkOccNameFS clsName
  
  -- demoteOccName lowers the Namespace of OccName.
  -- see Note [Demotion]
  demoteOccName :: OccName -> Maybe OccName
  demoteOccName (OccName space name) = do
    space' <- demoteNameSpace space
    return $ OccName space' name
  
  -- Name spaces are related if there is a chance to mean the one when one writes
  -- the other, i.e. variables <-> data constructors and type variables <-> type constructors
  nameSpacesRelated :: NameSpace -> NameSpace -> Bool
  nameSpacesRelated ns1 ns2 = ns1 == ns2 || otherNameSpace ns1 == ns2
  
  otherNameSpace :: NameSpace -> NameSpace
  otherNameSpace VarName = DataName
  otherNameSpace DataName = VarName
  otherNameSpace TvName = TcClsName
  otherNameSpace TcClsName = TvName
  
  
  
  {- | Other names in the compiler add additional information to an OccName.
  This class provides a consistent way to access the underlying OccName. -}
  class HasOccName name where
    occName :: name -> OccName
  
  {-
  ************************************************************************
  *                                                                      *
                  Environments
  *                                                                      *
  ************************************************************************
  
  OccEnvs are used mainly for the envts in ModIfaces.
  
  Note [The Unique of an OccName]
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  They are efficient, because FastStrings have unique Int# keys.  We assume
  this key is less than 2^24, and indeed FastStrings are allocated keys
  sequentially starting at 0.
  
  So we can make a Unique using
          mkUnique ns key  :: Unique
  where 'ns' is a Char representing the name space.  This in turn makes it
  easy to build an OccEnv.
  -}
  
  instance Uniquable OccName where
        -- See Note [The Unique of an OccName]
    getUnique (OccName VarName   fs) = mkVarOccUnique  fs
    getUnique (OccName DataName  fs) = mkDataOccUnique fs
    getUnique (OccName TvName    fs) = mkTvOccUnique   fs
    getUnique (OccName TcClsName fs) = mkTcOccUnique   fs
  
  newtype OccEnv a = A (UniqFM a)
  
  emptyOccEnv :: OccEnv a
  unitOccEnv  :: OccName -> a -> OccEnv a
  extendOccEnv :: OccEnv a -> OccName -> a -> OccEnv a
  extendOccEnvList :: OccEnv a -> [(OccName, a)] -> OccEnv a
  lookupOccEnv :: OccEnv a -> OccName -> Maybe a
  mkOccEnv     :: [(OccName,a)] -> OccEnv a
  mkOccEnv_C   :: (a -> a -> a) -> [(OccName,a)] -> OccEnv a
  elemOccEnv   :: OccName -> OccEnv a -> Bool
  foldOccEnv   :: (a -> b -> b) -> b -> OccEnv a -> b
  occEnvElts   :: OccEnv a -> [a]
  extendOccEnv_C :: (a->a->a) -> OccEnv a -> OccName -> a -> OccEnv a
  extendOccEnv_Acc :: (a->b->b) -> (a->b) -> OccEnv b -> OccName -> a -> OccEnv b
  plusOccEnv     :: OccEnv a -> OccEnv a -> OccEnv a
  plusOccEnv_C   :: (a->a->a) -> OccEnv a -> OccEnv a -> OccEnv a
  mapOccEnv      :: (a->b) -> OccEnv a -> OccEnv b
  delFromOccEnv      :: OccEnv a -> OccName -> OccEnv a
  delListFromOccEnv :: OccEnv a -> [OccName] -> OccEnv a
  filterOccEnv       :: (elt -> Bool) -> OccEnv elt -> OccEnv elt
  alterOccEnv        :: (Maybe elt -> Maybe elt) -> OccEnv elt -> OccName -> OccEnv elt
  
  emptyOccEnv      = A emptyUFM
  unitOccEnv x y = A $ unitUFM x y
  extendOccEnv (A x) y z = A $ addToUFM x y z
  extendOccEnvList (A x) l = A $ addListToUFM x l
  lookupOccEnv (A x) y = lookupUFM x y
  mkOccEnv     l    = A $ listToUFM l
  elemOccEnv x (A y)       = elemUFM x y
  foldOccEnv a b (A c)     = foldUFM a b c
  occEnvElts (A x)         = eltsUFM x
  plusOccEnv (A x) (A y)   = A $ plusUFM x y
  plusOccEnv_C f (A x) (A y)       = A $ plusUFM_C f x y
  extendOccEnv_C f (A x) y z   = A $ addToUFM_C f x y z
  extendOccEnv_Acc f g (A x) y z   = A $ addToUFM_Acc f g x y z
  mapOccEnv f (A x)        = A $ mapUFM f x
  mkOccEnv_C comb l = A $ addListToUFM_C comb emptyUFM l
  delFromOccEnv (A x) y    = A $ delFromUFM x y
  delListFromOccEnv (A x) y  = A $ delListFromUFM x y
  filterOccEnv x (A y)       = A $ filterUFM x y
  alterOccEnv fn (A y) k     = A $ alterUFM fn y k
  
  instance Outputable a => Outputable (OccEnv a) where
      ppr x = pprOccEnv ppr x
  
  pprOccEnv :: (a -> SDoc) -> OccEnv a -> SDoc
  pprOccEnv ppr_elt (A env) = pprUniqFM ppr_elt env
  
  type OccSet = UniqSet OccName
  
  emptyOccSet       :: OccSet
  unitOccSet        :: OccName -> OccSet
  mkOccSet          :: [OccName] -> OccSet
  extendOccSet      :: OccSet -> OccName -> OccSet
  extendOccSetList  :: OccSet -> [OccName] -> OccSet
  unionOccSets      :: OccSet -> OccSet -> OccSet
  unionManyOccSets  :: [OccSet] -> OccSet
  minusOccSet       :: OccSet -> OccSet -> OccSet
  elemOccSet        :: OccName -> OccSet -> Bool
  isEmptyOccSet     :: OccSet -> Bool
  intersectOccSet   :: OccSet -> OccSet -> OccSet
  intersectsOccSet  :: OccSet -> OccSet -> Bool
  
  emptyOccSet       = emptyUniqSet
  unitOccSet        = unitUniqSet
  mkOccSet          = mkUniqSet
  extendOccSet      = addOneToUniqSet
  extendOccSetList  = addListToUniqSet
  unionOccSets      = unionUniqSets
  unionManyOccSets  = unionManyUniqSets
  minusOccSet       = minusUniqSet
  elemOccSet        = elementOfUniqSet
  isEmptyOccSet     = isEmptyUniqSet
  intersectOccSet   = intersectUniqSets
  intersectsOccSet s1 s2 = not (isEmptyOccSet (s1 `intersectOccSet` s2))
  
  {-
  ************************************************************************
  *                                                                      *
  \subsection{Predicates and taking them apart}
  *                                                                      *
  ************************************************************************
  -}
  
  occNameString :: OccName -> String
  occNameString (OccName _ s) = unpackFS s
  
  setOccNameSpace :: NameSpace -> OccName -> OccName
  setOccNameSpace sp (OccName _ occ) = OccName sp occ
  
  isVarOcc, isTvOcc, isTcOcc, isDataOcc :: OccName -> Bool
  
  isVarOcc (OccName VarName _) = True
  isVarOcc _                   = False
  
  isTvOcc (OccName TvName _) = True
  isTvOcc _                  = False
  
  isTcOcc (OccName TcClsName _) = True
  isTcOcc _                     = False
  
  -- | /Value/ 'OccNames's are those that are either in
  -- the variable or data constructor namespaces
  isValOcc :: OccName -> Bool
  isValOcc (OccName VarName  _) = True
  isValOcc (OccName DataName _) = True
  isValOcc _                    = False
  
  isDataOcc (OccName DataName _) = True
  isDataOcc _                    = False
  
  -- | Test if the 'OccName' is a data constructor that starts with
  -- a symbol (e.g. @:@, or @[]@)
  isDataSymOcc :: OccName -> Bool
  isDataSymOcc (OccName DataName s) = isLexConSym s
  isDataSymOcc _                    = False
  -- Pretty inefficient!
  
  -- | Test if the 'OccName' is that for any operator (whether
  -- it is a data constructor or variable or whatever)
  isSymOcc :: OccName -> Bool
  isSymOcc (OccName DataName s)  = isLexConSym s
  isSymOcc (OccName TcClsName s) = isLexSym s
  isSymOcc (OccName VarName s)   = isLexSym s
  isSymOcc (OccName TvName s)    = isLexSym s
  -- Pretty inefficient!
  
  parenSymOcc :: OccName -> SDoc -> SDoc
  -- ^ Wrap parens around an operator
  parenSymOcc occ doc | isSymOcc occ = parens doc
                      | otherwise    = doc
  
  startsWithUnderscore :: OccName -> Bool
  -- ^ Haskell 98 encourages compilers to suppress warnings about unsed
  -- names in a pattern if they start with @_@: this implements that test
  startsWithUnderscore occ = case occNameString occ of
                               ('_' : _) -> True
                               _other    -> False
  
  {-
  ************************************************************************
  *                                                                      *
  \subsection{Making system names}
  *                                                                      *
  ************************************************************************
  
  Here's our convention for splitting up the interface file name space:
  
     d...         dictionary identifiers
                  (local variables, so no name-clash worries)
  
  All of these other OccNames contain a mixture of alphabetic
  and symbolic characters, and hence cannot possibly clash with
  a user-written type or function name
  
     $f...        Dict-fun identifiers (from inst decls)
     $dmop        Default method for 'op'
     $pnC         n'th superclass selector for class C
     $wf          Worker for functtoin 'f'
     $sf..        Specialised version of f
     T:C          Tycon for dictionary for class C
     D:C          Data constructor for dictionary for class C
     NTCo:T       Coercion connecting newtype T with its representation type
     TFCo:R       Coercion connecting a data family to its respresentation type R
  
  In encoded form these appear as Zdfxxx etc
  
          :...            keywords (export:, letrec: etc.)
  --- I THINK THIS IS WRONG!
  
  This knowledge is encoded in the following functions.
  
  @mk_deriv@ generates an @OccName@ from the prefix and a string.
  NB: The string must already be encoded!
  -}
  
  mk_deriv :: NameSpace
           -> String              -- Distinguishes one sort of derived name from another
           -> String
           -> OccName
  
  mk_deriv occ_sp sys_prefix str = mkOccName occ_sp (sys_prefix ++ str)
  
  isDerivedOccName :: OccName -> Bool
  isDerivedOccName occ =
     case occNameString occ of
       '$':c:_ | isAlphaNum c -> True
       ':':c:_ | isAlphaNum c -> True
       _other                 -> False
  
  mkDataConWrapperOcc, mkWorkerOcc,
          mkMatcherOcc, mkBuilderOcc,
          mkDefaultMethodOcc,
          mkGenDefMethodOcc, mkDerivedTyConOcc, mkClassDataConOcc, mkDictOcc,
          mkIPOcc, mkSpecOcc, mkForeignExportOcc, mkRepEqOcc, mkGenOcc1, mkGenOcc2,
          mkGenD, mkGenR, mkGen1R, mkGenRCo,
          mkDataTOcc, mkDataCOcc, mkDataConWorkerOcc, mkNewTyCoOcc,
          mkInstTyCoOcc, mkEqPredCoOcc, mkClassOpAuxOcc,
          mkCon2TagOcc, mkTag2ConOcc, mkMaxTagOcc, mkJavaImportOcc
     :: OccName -> OccName
  
  -- These derived variables have a prefix that no Haskell value could have
  mkDataConWrapperOcc = mk_simple_deriv varName  "$$W"
  mkWorkerOcc         = mk_simple_deriv varName  "$w"
  mkMatcherOcc        = mk_simple_deriv varName  "$m"
  mkBuilderOcc        = mk_simple_deriv varName  "$b"
  mkDefaultMethodOcc  = mk_simple_deriv varName  "$dm"
  mkGenDefMethodOcc   = mk_simple_deriv varName  "$gdm"
  mkClassOpAuxOcc     = mk_simple_deriv varName  "$c"
  mkDerivedTyConOcc   = mk_simple_deriv tcName   ":"      -- The : prefix makes sure it classifies as a tycon/datacon
  mkClassDataConOcc   = mk_simple_deriv dataName "D:"     -- We go straight to the "real" data con
                                                          -- for datacons from classes
  mkDictOcc           = mk_simple_deriv varName  "$d"
  mkIPOcc             = mk_simple_deriv varName  "$i"
  mkSpecOcc           = mk_simple_deriv varName  "$s"
  mkForeignExportOcc  = mk_simple_deriv varName  "$fe_"
  mkRepEqOcc          = mk_simple_deriv tvName   "$r"      -- In RULES involving Coercible
  mkNewTyCoOcc        = mk_simple_deriv tcName   "NTCo:"  -- Coercion for newtypes
  mkInstTyCoOcc       = mk_simple_deriv tcName   "TFCo:"   -- Coercion for type functions
  mkEqPredCoOcc       = mk_simple_deriv tcName   "$co"
  mkJavaImportOcc     = mk_simple_deriv tcName   "$ji"
  
  -- used in derived instances
  mkCon2TagOcc        = mk_simple_deriv varName  "$con2tag_"
  mkTag2ConOcc        = mk_simple_deriv varName  "$tag2con_"
  mkMaxTagOcc         = mk_simple_deriv varName  "$maxtag_"
  
  -- Generic derivable classes (old)
  mkGenOcc1           = mk_simple_deriv varName  "$gfrom"
  mkGenOcc2           = mk_simple_deriv varName  "$gto"
  
  -- Generic deriving mechanism (new)
  mkGenD         = mk_simple_deriv tcName "D1"
  
  mkGenC :: OccName -> Int -> OccName
  mkGenC occ m   = mk_deriv tcName ("C1_" ++ show m) (occNameString occ)
  
  mkGenS :: OccName -> Int -> Int -> OccName
  mkGenS occ m n = mk_deriv tcName ("S1_" ++ show m ++ "_" ++ show n)
                     (occNameString occ)
  
  mkGenR   = mk_simple_deriv tcName "Rep_"
  mkGen1R  = mk_simple_deriv tcName "Rep1_"
  mkGenRCo = mk_simple_deriv tcName "CoRep_"
  
  -- data T = MkT ... deriving( Data ) needs definitions for
  --      $tT   :: Data.Generics.Basics.DataType
  --      $cMkT :: Data.Generics.Basics.Constr
  mkDataTOcc = mk_simple_deriv varName  "$t"
  mkDataCOcc = mk_simple_deriv varName  "$c"
  
  -- Vectorisation
  mkVectOcc, mkVectTyConOcc, mkVectDataConOcc, mkVectIsoOcc,
   mkPADFunOcc,      mkPReprTyConOcc,
   mkPDataTyConOcc,  mkPDataDataConOcc,
   mkPDatasTyConOcc, mkPDatasDataConOcc
    :: Maybe String -> OccName -> OccName
  mkVectOcc          = mk_simple_deriv_with varName  "$v"
  mkVectTyConOcc     = mk_simple_deriv_with tcName   "V:"
  mkVectDataConOcc   = mk_simple_deriv_with dataName "VD:"
  mkVectIsoOcc       = mk_simple_deriv_with varName  "$vi"
  mkPADFunOcc        = mk_simple_deriv_with varName  "$pa"
  mkPReprTyConOcc    = mk_simple_deriv_with tcName   "VR:"
  mkPDataTyConOcc    = mk_simple_deriv_with tcName   "VP:"
  mkPDatasTyConOcc   = mk_simple_deriv_with tcName   "VPs:"
  mkPDataDataConOcc  = mk_simple_deriv_with dataName "VPD:"
  mkPDatasDataConOcc = mk_simple_deriv_with dataName "VPDs:"
  
  mk_simple_deriv :: NameSpace -> String -> OccName -> OccName
  mk_simple_deriv sp px occ = mk_deriv sp px (occNameString occ)
  
  mk_simple_deriv_with :: NameSpace -> String -> Maybe String -> OccName -> OccName
  mk_simple_deriv_with sp px Nothing     occ = mk_deriv sp px                  (occNameString occ)
  mk_simple_deriv_with sp px (Just with) occ = mk_deriv sp (px ++ with ++ "_") (occNameString occ)
  
  -- Data constructor workers are made by setting the name space
  -- of the data constructor OccName (which should be a DataName)
  -- to VarName
  mkDataConWorkerOcc datacon_occ = setOccNameSpace varName datacon_occ
  
  mkSuperDictSelOcc :: Int        -- ^ Index of superclass, e.g. 3
                    -> OccName    -- ^ Class, e.g. @Ord@
                    -> OccName    -- ^ Derived 'Occname', e.g. @$p3Ord@
  mkSuperDictSelOcc index cls_tc_occ
    = mk_deriv varName "$p" (show index ++ occNameString cls_tc_occ)
  
  mkLocalOcc :: Unique            -- ^ Unique to combine with the 'OccName'
             -> OccName           -- ^ Local name, e.g. @sat@
             -> OccName           -- ^ Nice unique version, e.g. @$L23sat@
  mkLocalOcc uniq occ
     = mk_deriv varName ("$L" ++ show uniq) (occNameString occ)
          -- The Unique might print with characters
          -- that need encoding (e.g. 'z'!)
  
  mkLocalOccWithoutUnique :: OccName -- ^ Local name, e.g. @sat@
                          -> OccName -- ^ Nice localized version, e.g. @$Lsat@
  mkLocalOccWithoutUnique occ
     = mk_deriv varName "$L" (occNameString occ)
          -- The Unique might print with characters
          -- that need encoding (e.g. 'z'!)
  
  -- | Derive a name for the representation type constructor of a
  -- @data@\/@newtype@ instance.
  mkInstTyTcOcc :: String                 -- ^ Family name, e.g. @Map@
                -> OccSet                 -- ^ avoid these Occs
                -> OccName                -- ^ @R:Map@
  mkInstTyTcOcc str set =
    chooseUniqueOcc tcName ('R' : ':' : str) set
  
  mkDFunOcc :: String             -- ^ Typically the class and type glommed together e.g. @OrdMaybe@.
                                  -- Only used in debug mode, for extra clarity
            -> Bool               -- ^ Is this a hs-boot instance DFun?
            -> OccSet             -- ^ avoid these Occs
            -> OccName            -- ^ E.g. @$f3OrdMaybe@
  
  -- In hs-boot files we make dict funs like $fx7ClsTy, which get bound to the real
  -- thing when we compile the mother module. Reason: we don't know exactly
  -- what the  mother module will call it.
  
  mkDFunOcc info_str is_boot set
    = chooseUniqueOcc VarName (prefix ++ info_str) set
    where
      prefix | is_boot   = "$fx"
             | otherwise = "$f"
  
  {-
  Sometimes we need to pick an OccName that has not already been used,
  given a set of in-use OccNames.
  -}
  
  chooseUniqueOcc :: NameSpace -> String -> OccSet -> OccName
  chooseUniqueOcc ns str set = loop (mkOccName ns str) (0::Int)
    where
    loop occ n
     | occ `elemOccSet` set = loop (mkOccName ns (str ++ show n)) (n+1)
     | otherwise            = occ
  
  {-
  We used to add a '$m' to indicate a method, but that gives rise to bad
  error messages from the type checker when we print the function name or pattern
  of an instance-decl binding.  Why? Because the binding is zapped
  to use the method name in place of the selector name.
  (See TcClassDcl.tcMethodBind)
  
  The way it is now, -ddump-xx output may look confusing, but
  you can always say -dppr-debug to get the uniques.
  
  However, we *do* have to zap the first character to be lower case,
  because overloaded constructors (blarg) generate methods too.
  And convert to VarName space
  
  e.g. a call to constructor MkFoo where
          data (Ord a) => Foo a = MkFoo a
  
  If this is necessary, we do it by prefixing '$m'.  These
  guys never show up in error messages.  What a hack.
  -}
  
  mkMethodOcc :: OccName -> OccName
  mkMethodOcc occ@(OccName VarName _) = occ
  mkMethodOcc occ                     = mk_simple_deriv varName "$m" occ
  
  {-
  ************************************************************************
  *                                                                      *
  \subsection{Tidying them up}
  *                                                                      *
  ************************************************************************
  
  Before we print chunks of code we like to rename it so that
  we don't have to print lots of silly uniques in it.  But we mustn't
  accidentally introduce name clashes!  So the idea is that we leave the
  OccName alone unless it accidentally clashes with one that is already
  in scope; if so, we tack on '1' at the end and try again, then '2', and
  so on till we find a unique one.
  
  There's a wrinkle for operators.  Consider '>>='.  We can't use '>>=1'
  because that isn't a single lexeme.  So we encode it to 'lle' and *then*
  tack on the '1', if necessary.
  
  Note [TidyOccEnv]
  ~~~~~~~~~~~~~~~~~
  type TidyOccEnv = UniqFM Int
  
  * Domain = The OccName's FastString. These FastStrings are "taken";
             make sure that we don't re-use
  
  * Int, n = A plausible starting point for new guesses
             There is no guarantee that "FSn" is available;
             you must look that up in the TidyOccEnv.  But
             it's a good place to start looking.
  
  * When looking for a renaming for "foo2" we strip off the "2" and start
    with "foo".  Otherwise if we tidy twice we get silly names like foo23.
  
    However, if it started with digits at the end, we always make a name
    with digits at the end, rather than shortening "foo2" to just "foo",
    even if "foo" is unused.  Reasons:
       - Plain "foo" might be used later
       - We use trailing digits to subtly indicate a unification variable
         in typechecker error message; see TypeRep.tidyTyVarBndr
  
  We have to take care though! Consider a machine-generated module (Trac #10370)
    module Foo where
       a1 = e1
       a2 = e2
       ...
       a2000 = e2000
  Then "a1", "a2" etc are all marked taken.  But now if we come across "a7" again,
  we have to do a linear search to find a free one, "a20001".  That might just be
  acceptable once.  But if we now come across "a8" again, we don't want to repeat
  that search.
  
  So we use the TidyOccEnv mapping for "a" (not "a7" or "a8") as our base for
  starting the search; and we make sure to update the starting point for "a"
  after we allocate a new one.
  
  -}
  
  type TidyOccEnv = UniqFM Int    -- The in-scope OccNames
    -- See Note [TidyOccEnv]
  
  emptyTidyOccEnv :: TidyOccEnv
  emptyTidyOccEnv = emptyUFM
  
  initTidyOccEnv :: [OccName] -> TidyOccEnv       -- Initialise with names to avoid!
  initTidyOccEnv = foldl add emptyUFM
    where
      add env (OccName _ fs) = addToUFM env fs 1
  
  tidyOccName :: TidyOccEnv -> OccName -> (TidyOccEnv, OccName)
  tidyOccName env occ@(OccName occ_sp fs)
    = case lookupUFM env fs of
        Nothing -> (addToUFM env fs 1, occ)   -- Desired OccName is free
        Just {} -> case lookupUFM env base1 of
                     Nothing -> (addToUFM env base1 2, OccName occ_sp base1)
                     Just n  -> find 1 n
    where
      base :: String  -- Drop trailing digits (see Note [TidyOccEnv])
      base  = dropWhileEndLE isDigit (unpackFS fs)
      base1 = mkFastString (base ++ "1")
  
      find !k !n
        = case lookupUFM env new_fs of
            Just {} -> find (k+1 :: Int) (n+k)
                         -- By using n+k, the n arguemt to find goes
                         --    1, add 1, add 2, add 3, etc which
                         -- moves at quadratic speed through a dense patch
  
            Nothing -> (new_env, OccName occ_sp new_fs)
         where
           new_fs = mkFastString (base ++ show n)
           new_env = addToUFM (addToUFM env new_fs 1) base1 (n+1)
                       -- Update:  base_fs, so that next time we'll start whwere we left off
                       --          new_fs,  so that we know it is taken
                       -- If they are the same (n==1), the former wins
                       -- See Note [TidyOccEnv]
  
  {-
  ************************************************************************
  *                                                                      *
                  Binary instance
      Here rather than BinIface because OccName is abstract
  *                                                                      *
  ************************************************************************
  -}
  
  instance Binary NameSpace where
      put_ bh VarName = do
              putByte bh 0
      put_ bh DataName = do
              putByte bh 1
      put_ bh TvName = do
              putByte bh 2
      put_ bh TcClsName = do
              putByte bh 3
      get bh = do
              h <- getByte bh
              case h of
                0 -> do return VarName
                1 -> do return DataName
                2 -> do return TvName
                _ -> do return TcClsName
  
  instance Binary OccName where
      put_ bh (OccName aa ab) = do
              put_ bh aa
              put_ bh ab
      get bh = do
            aa <- get bh
            ab <- get bh
            return (OccName aa ab)
  