basicTypes/OccName.lhs

% % (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \begin{code}

    -- |
    -- #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"

    {-# OPTIONS -fno-warn-tabs #-}
    -- The above warning supression flag is a temporary kludge.
    -- While working on this module you are encouraged to remove it and
    -- detab the module (please do the detabbing in a separate patch). See
    --     http://ghc.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
    -- for details

    module OccName (
    	-- * The 'NameSpace' type
    	NameSpace, -- Abstract

    	-- ** 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, mkDefaultMethodOcc,
            mkGenDefMethodOcc,
    	mkDerivedTyConOcc, mkNewTyCoOcc, mkClassOpAuxOcc,
            mkCon2TagOcc, mkTag2ConOcc, mkMaxTagOcc,
      	mkClassDataConOcc, mkDictOcc, mkIPOcc,
     	mkSpecOcc, mkForeignExportOcc, mkGenOcc1, mkGenOcc2,
     	mkGenD, mkGenR, mkGen1R, mkGenRCo, mkGenC, mkGenS,
            mkDataTOcc, mkDataCOcc, mkDataConWorkerOcc,
    	mkSuperDictSelOcc, mkLocalOcc, mkMethodOcc, mkInstTyTcOcc,
    	mkInstTyCoOcc, mkEqPredCoOcc,
            mkVectOcc, mkVectTyConOcc, mkVectDataConOcc, mkVectIsoOcc,
            mkPDataTyConOcc,  mkPDataDataConOcc,
    	mkPDatasTyConOcc, mkPDatasDataConOcc,
            mkPReprTyConOcc,
            mkPADFunOcc,

    	-- ** 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, occSetElts,
    	foldOccSet, isEmptyOccSet, intersectOccSet, intersectsOccSet,

    	-- * Tidying up
    	TidyOccEnv, emptyTidyOccEnv, tidyOccName, initTidyOccEnv,

    	-- * Lexical characteristics of Haskell names
    	isLexCon, isLexVar, isLexId, isLexSym,
    	isLexConId, isLexConSym, isLexVarId, isLexVarSym,
    	startsVarSym, startsVarId, startsConSym, startsConId
        ) where

    import Util
    import Unique
    import DynFlags
    import UniqFM
    import UniqSet
    import FastString
    import Outputable
    import Binary
    import Data.Char
    import Data.Data

\end{code} %************************************************************************ %* * \subsection{Name space} %* * %************************************************************************ \begin{code}

    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

\end{code} %************************************************************************ %* * \subsection[Name-pieces-datatypes]{The @OccName@ datatypes} %* * %************************************************************************ \begin{code}

    data OccName = OccName
        { occNameSpace  :: !NameSpace
        , occNameFS     :: !FastString
        }
        deriving Typeable

\end{code} \begin{code}

    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"

\end{code} %************************************************************************ %* * \subsection{Printing} %* * %************************************************************************ \begin{code}

    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 []       = []

\end{code} 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} %* * %************************************************************************ \begin{code}

    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

    {- | Other names in the compiler add aditional information to an OccName.
    This class provides a consistent way to access the underlying OccName. -}
    class HasOccName name where
      occName :: name -> OccName

\end{code} %************************************************************************ %* * 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. \begin{code}

    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
    occSetElts	  :: OccSet -> [OccName]
    foldOccSet	  :: (OccName -> b -> b) -> b -> OccSet -> b
    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
    occSetElts        = uniqSetToList
    foldOccSet	  = foldUniqSet
    isEmptyOccSet     = isEmptyUniqSet
    intersectOccSet   = intersectUniqSets
    intersectsOccSet s1 s2 = not (isEmptyOccSet (s1 `intersectOccSet` s2))

\end{code} %************************************************************************ %* * \subsection{Predicates and taking them apart} %* * %************************************************************************ \begin{code}

    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

\end{code} \begin{code}

    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

\end{code} %************************************************************************ %* * \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! \begin{code}

    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

\end{code} \begin{code}

    mkDataConWrapperOcc, mkWorkerOcc, mkMatcherOcc, mkDefaultMethodOcc,
            mkGenDefMethodOcc, mkDerivedTyConOcc, mkClassDataConOcc, mkDictOcc,
     	mkIPOcc, mkSpecOcc, mkForeignExportOcc, mkGenOcc1, mkGenOcc2,
     	mkGenD, mkGenR, mkGen1R, mkGenRCo,
    	mkDataTOcc, mkDataCOcc, mkDataConWorkerOcc, mkNewTyCoOcc,
    	mkInstTyCoOcc, mkEqPredCoOcc, mkClassOpAuxOcc,
            mkCon2TagOcc, mkTag2ConOcc, mkMaxTagOcc
       :: 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  "$m"
    mkDefaultMethodOcc  = mk_simple_deriv varName  "$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  "$s"
    mkForeignExportOcc  = mk_simple_deriv varName  "$f"
    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"

    -- 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

\end{code} \begin{code}

    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'!)

\end{code} \begin{code}

    -- | 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

\end{code} \begin{code}

    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"

\end{code} Sometimes we need to pick an OccName that has not already been used, given a set of in-use OccNames. \begin{code}

    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

\end{code} 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. \begin{code}

    mkMethodOcc :: OccName -> OccName
    mkMethodOcc occ@(OccName VarName _) = occ
    mkMethodOcc occ                     = mk_simple_deriv varName "$m" occ

\end{code} %************************************************************************ %* * \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. \begin{code}

    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
    	Just n  -> find n
    	Nothing -> (addToUFM env fs 1, occ)
      where
        base :: String  -- Drop trailing digits (see Note [TidyOccEnv])
        base = reverse (dropWhile isDigit (reverse (unpackFS fs)))

        find n
          = case lookupUFM env new_fs of
              Just n' -> find (n1 `max` n')
                         -- The max ensures that n increases, avoiding loops
              Nothing -> (addToUFM (addToUFM env fs n1) new_fs n1,
                          OccName occ_sp new_fs)
                         -- We update only the beginning and end of the
                         -- chain that find explores; it's a little harder to
                         -- update the middle and there's no real need.
           where
             n1 = n+1
             new_fs = mkFastString (base ++ show n)

\end{code} %************************************************************************ %* * \subsection{Lexical categories} %* * %************************************************************************ These functions test strings to see if they fit the lexical categories defined in the Haskell report. Note [Classification of generated names] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Some names generated for internal use can show up in debugging output, e.g. when using -ddump-simpl. These generated names start with a $ but should still be pretty-printed using prefix notation. We make sure this is the case in isLexVarSym by only classifying a name as a symbol if all its characters are symbols, not just its first one. \begin{code}

    isLexCon,   isLexVar,    isLexId,    isLexSym    :: FastString -> Bool
    isLexConId, isLexConSym, isLexVarId, isLexVarSym :: FastString -> Bool

    isLexCon cs = isLexConId  cs || isLexConSym cs
    isLexVar cs = isLexVarId  cs || isLexVarSym cs

    isLexId  cs = isLexConId  cs || isLexVarId  cs
    isLexSym cs = isLexConSym cs || isLexVarSym cs

    -------------

    isLexConId cs				-- Prefix type or data constructors
      | nullFS cs	       = False		-- 	e.g. "Foo", "[]", "(,)"
      | cs == (fsLit "[]") = True
      | otherwise	       = startsConId (headFS cs)

    isLexVarId cs				-- Ordinary prefix identifiers
      | nullFS cs	      = False		-- 	e.g. "x", "_x"
      | otherwise         = startsVarId (headFS cs)

    isLexConSym cs				-- Infix type or data constructors
      | nullFS cs	       = False		--	e.g. ":-:", ":", "->"
      | cs == (fsLit "->") = True
      | otherwise	       = startsConSym (headFS cs)

    isLexVarSym fs				-- Infix identifiers e.g. "+"
      = case (if nullFS fs then [] else unpackFS fs) of
          [] -> False
          (c:cs) -> startsVarSym c && all isVarSymChar cs

    -------------
    startsVarSym, startsVarId, startsConSym, startsConId :: Char -> Bool
    startsVarSym c = isSymbolASCII c || (ord c > 0x7f && isSymbol c)  -- Infix Ids
    startsConSym c = c == ':'		-- Infix data constructors
    startsVarId c  = isLower c || c == '_'	-- Ordinary Ids
    startsConId c  = isUpper c || c == '('	-- Ordinary type constructors and data constructors

    isSymbolASCII :: Char -> Bool
    isSymbolASCII c = c `elem` "!#$%&*+./<=>?@\\^|~-"

    isVarSymChar :: Char -> Bool
    isVarSymChar c = c == ':' || startsVarSym c

\end{code} %************************************************************************ %* * Binary instance Here rather than BinIface because OccName is abstract %* * %************************************************************************ \begin{code}

    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)

\end{code}