Name.lhs 20.2 KB
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% (c) The University of Glasgow 2006
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% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
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\section[Name]{@Name@: to transmit name info from renamer to typechecker}

\begin{code}
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{-# 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://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
-- for details

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-- |
-- #name_types#
-- GHC uses several kinds of name internally:
--
-- * 'OccName.OccName': see "OccName#name_types"
--
-- * 'RdrName.RdrName': see "RdrName#name_types"
--
-- *  'Name.Name' is the type of names that have had their scoping and binding resolved. They
--   have an 'OccName.OccName' but also a 'Unique.Unique' that disambiguates Names that have
--   the same 'OccName.OccName' and indeed is used for all 'Name.Name' comparison. Names
--   also contain information about where they originated from, see "Name#name_sorts"
--
-- * 'Id.Id': see "Id#name_types"
--
-- * 'Var.Var': see "Var#name_types"
--
-- #name_sorts#
-- Names are one of:
--
--  * External, if they name things declared in other modules. Some external
--    Names are wired in, i.e. they name primitives defined in the compiler itself
--
--  * Internal, if they name things in the module being compiled. Some internal
--    Names are system names, if they are names manufactured by the compiler
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module Name (
	-- * The main types
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	Name,					-- Abstract
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	BuiltInSyntax(..),

	-- ** Creating 'Name's
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	mkSystemName, mkSystemNameAt,
        mkInternalName, mkDerivedInternalName, 
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	mkSystemVarName, mkSysTvName, 
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        mkFCallName,
        mkExternalName, mkWiredInName,
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	-- ** Manipulating and deconstructing 'Name's
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	nameUnique, setNameUnique,
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	nameOccName, nameModule, nameModule_maybe,
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	tidyNameOcc, 
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	hashName, localiseName,
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        mkLocalisedOccName,
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	nameSrcLoc, nameSrcSpan, pprNameDefnLoc, pprDefinedAt,
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	-- ** Predicates on 'Name's
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	isSystemName, isInternalName, isExternalName,
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	isTyVarName, isTyConName, isDataConName, 
	isValName, isVarName,
	isWiredInName, isBuiltInSyntax,
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	wiredInNameTyThing_maybe, 
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	nameIsLocalOrFrom, stableNameCmp,
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	-- * Class 'NamedThing' and overloaded friends
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	NamedThing(..),
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	getSrcLoc, getSrcSpan, getOccString,
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 	pprInfixName, pprPrefixName, pprModulePrefix,
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	-- Re-export the OccName stuff
	module OccName
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    ) where
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#include "Typeable.h"

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import {-# SOURCE #-} TypeRep( TyThing )

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import OccName
import Module
import SrcLoc
import Unique
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import Util
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import Maybes
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import Binary
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import StaticFlags
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import FastTypes
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import FastString
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import Outputable
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import Data.Data
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\end{code}

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%************************************************************************
%*									*
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\subsection[Name-datatype]{The @Name@ datatype, and name construction}
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%*									*
%************************************************************************
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\begin{code}
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-- | A unique, unambigious name for something, containing information about where
-- that thing originated.
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data Name = Name {
		n_sort :: NameSort,	-- What sort of name it is
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		n_occ  :: !OccName,	-- Its occurrence name
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		n_uniq :: FastInt,      -- UNPACK doesn't work, recursive type
--(note later when changing Int# -> FastInt: is that still true about UNPACK?)
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		n_loc  :: !SrcSpan	-- Definition site
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	    }
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    deriving Typeable
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-- NOTE: we make the n_loc field strict to eliminate some potential
-- (and real!) space leaks, due to the fact that we don't look at
-- the SrcLoc in a Name all that often.

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data NameSort
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  = External Module
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  | WiredIn Module TyThing BuiltInSyntax
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	-- A variant of External, for wired-in things
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  | Internal		-- A user-defined Id or TyVar
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			-- defined in the module being compiled

  | System		-- A system-defined Id or TyVar.  Typically the
			-- OccName is very uninformative (like 's')
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-- | BuiltInSyntax is for things like @(:)@, @[]@ and tuples, 
-- which have special syntactic forms.  They aren't in scope
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-- as such.
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data BuiltInSyntax = BuiltInSyntax | UserSyntax
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\end{code}

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Notes about the NameSorts:

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1.  Initially, top-level Ids (including locally-defined ones) get External names, 
    and all other local Ids get Internal names
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2.  Things with a External name are given C static labels, so they finally
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    appear in the .o file's symbol table.  They appear in the symbol table
    in the form M.n.  If originally-local things have this property they
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    must be made @External@ first.
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3.  In the tidy-core phase, a External that is not visible to an importer
    is changed to Internal, and a Internal that is visible is changed to External
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4.  A System Name differs in the following ways:
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	a) has unique attached when printing dumps
	b) unifier eliminates sys tyvars in favour of user provs where possible

    Before anything gets printed in interface files or output code, it's
    fed through a 'tidy' processor, which zaps the OccNames to have
    unique names; and converts all sys-locals to user locals
    If any desugarer sys-locals have survived that far, they get changed to
    "ds1", "ds2", etc.

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Built-in syntax => It's a syntactic form, not "in scope" (e.g. [])

Wired-in thing  => The thing (Id, TyCon) is fully known to the compiler, 
		   not read from an interface file. 
		   E.g. Bool, True, Int, Float, and many others

All built-in syntax is for wired-in things.

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\begin{code}
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instance HasOccName Name where
  occName = nameOccName

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nameUnique		:: Name -> Unique
nameOccName		:: Name -> OccName 
nameModule		:: Name -> Module
nameSrcLoc		:: Name -> SrcLoc
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nameSrcSpan		:: Name -> SrcSpan
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nameUnique  name = mkUniqueGrimily (iBox (n_uniq name))
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nameOccName name = n_occ  name
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nameSrcLoc  name = srcSpanStart (n_loc name)
nameSrcSpan name = n_loc  name
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\end{code}

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%************************************************************************
%*									*
\subsection{Predicates on names}
%*									*
%************************************************************************

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\begin{code}
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nameIsLocalOrFrom :: Module -> Name -> Bool
isInternalName	  :: Name -> Bool
isExternalName	  :: Name -> Bool
isSystemName	  :: Name -> Bool
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isWiredInName	  :: Name -> Bool

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isWiredInName (Name {n_sort = WiredIn _ _ _}) = True
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isWiredInName _                               = False
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wiredInNameTyThing_maybe :: Name -> Maybe TyThing
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wiredInNameTyThing_maybe (Name {n_sort = WiredIn _ thing _}) = Just thing
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wiredInNameTyThing_maybe _                                   = Nothing
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isBuiltInSyntax :: Name -> Bool
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isBuiltInSyntax (Name {n_sort = WiredIn _ _ BuiltInSyntax}) = True
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isBuiltInSyntax _                                           = False
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isExternalName (Name {n_sort = External _})    = True
isExternalName (Name {n_sort = WiredIn _ _ _}) = True
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isExternalName _                               = False
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isInternalName name = not (isExternalName name)
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nameModule name = nameModule_maybe name `orElse` pprPanic "nameModule" (ppr name)
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nameModule_maybe :: Name -> Maybe Module
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nameModule_maybe (Name { n_sort = External mod})    = Just mod
nameModule_maybe (Name { n_sort = WiredIn mod _ _}) = Just mod
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nameModule_maybe _                                  = Nothing
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nameIsLocalOrFrom from name
  | isExternalName name = from == nameModule name
  | otherwise		= True

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isTyVarName :: Name -> Bool
isTyVarName name = isTvOcc (nameOccName name)
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isTyConName :: Name -> Bool
isTyConName name = isTcOcc (nameOccName name)

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isDataConName :: Name -> Bool
isDataConName name = isDataOcc (nameOccName name)

isValName :: Name -> Bool
isValName name = isValOcc (nameOccName name)

isVarName :: Name -> Bool
isVarName = isVarOcc . nameOccName

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isSystemName (Name {n_sort = System}) = True
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isSystemName _                        = False
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\end{code}


%************************************************************************
%*									*
\subsection{Making names}
%*									*
%************************************************************************
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\begin{code}
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-- | Create a name which is (for now at least) local to the current module and hence
-- does not need a 'Module' to disambiguate it from other 'Name's
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mkInternalName :: Unique -> OccName -> SrcSpan -> Name
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mkInternalName uniq occ loc = Name { n_uniq = getKeyFastInt uniq
                                   , n_sort = Internal
                                   , n_occ = occ
                                   , n_loc = loc }
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	-- NB: You might worry that after lots of huffing and
	-- puffing we might end up with two local names with distinct
	-- uniques, but the same OccName.  Indeed we can, but that's ok
	--	* the insides of the compiler don't care: they use the Unique
	--	* when printing for -ddump-xxx you can switch on -dppr-debug to get the
	--	  uniques if you get confused
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        --      * for interface files we tidyCore first, which makes
        --        the OccNames distinct when they need to be
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mkDerivedInternalName :: (OccName -> OccName) -> Unique -> Name -> Name
mkDerivedInternalName derive_occ uniq (Name { n_occ = occ, n_loc = loc })
  = Name { n_uniq = getKeyFastInt uniq, n_sort = Internal
         , n_occ = derive_occ occ, n_loc = loc }

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-- | Create a name which definitely originates in the given module
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mkExternalName :: Unique -> Module -> OccName -> SrcSpan -> Name
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mkExternalName uniq mod occ loc 
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  = Name { n_uniq = getKeyFastInt uniq, n_sort = External mod,
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           n_occ = occ, n_loc = loc }
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-- | Create a name which is actually defined by the compiler itself
mkWiredInName :: Module -> OccName -> Unique -> TyThing -> BuiltInSyntax -> Name
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mkWiredInName mod occ uniq thing built_in
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  = Name { n_uniq = getKeyFastInt uniq,
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	   n_sort = WiredIn mod thing built_in,
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	   n_occ = occ, n_loc = wiredInSrcSpan }
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-- | Create a name brought into being by the compiler
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mkSystemName :: Unique -> OccName -> Name
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mkSystemName uniq occ = mkSystemNameAt uniq occ noSrcSpan

mkSystemNameAt :: Unique -> OccName -> SrcSpan -> Name
mkSystemNameAt uniq occ loc = Name { n_uniq = getKeyFastInt uniq, n_sort = System 
			           , n_occ = occ, n_loc = loc }
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mkSystemVarName :: Unique -> FastString -> Name
mkSystemVarName uniq fs = mkSystemName uniq (mkVarOccFS fs)
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mkSysTvName :: Unique -> FastString -> Name
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mkSysTvName uniq fs = mkSystemName uniq (mkOccNameFS tvName fs)
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-- | Make a name for a foreign call
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mkFCallName :: Unique -> String -> Name
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mkFCallName uniq str = mkInternalName uniq (mkVarOcc str) noSrcSpan
   -- The encoded string completely describes the ccall
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\end{code}

\begin{code}
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-- When we renumber/rename things, we need to be
-- able to change a Name's Unique to match the cached
-- one in the thing it's the name of.  If you know what I mean.
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setNameUnique :: Name -> Unique -> Name
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setNameUnique name uniq = name {n_uniq = getKeyFastInt uniq}
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tidyNameOcc :: Name -> OccName -> Name
-- We set the OccName of a Name when tidying
-- In doing so, we change System --> Internal, so that when we print
-- it we don't get the unique by default.  It's tidy now!
tidyNameOcc name@(Name { n_sort = System }) occ = name { n_occ = occ, n_sort = Internal}
tidyNameOcc name 			    occ = name { n_occ = occ }
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-- | Make the 'Name' into an internal name, regardless of what it was to begin with
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localiseName :: Name -> Name
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localiseName n = n { n_sort = Internal }
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\end{code}

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\begin{code}
-- |Create a localised variant of a name.  
--
-- If the name is external, encode the original's module name to disambiguate.
--
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mkLocalisedOccName :: Module -> (Maybe String -> OccName -> OccName) -> Name -> OccName
mkLocalisedOccName this_mod mk_occ name = mk_occ origin (nameOccName name)
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  where
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    origin 
      | nameIsLocalOrFrom this_mod name = Nothing
      | otherwise                       = Just (moduleNameColons . moduleName . nameModule $ name)
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\end{code}

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%************************************************************************
%*									*
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\subsection{Hashing and comparison}
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%*									*
%************************************************************************

\begin{code}
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hashName :: Name -> Int		-- ToDo: should really be Word
hashName name = getKey (nameUnique name) + 1
	-- The +1 avoids keys with lots of zeros in the ls bits, which 
	-- interacts badly with the cheap and cheerful multiplication in
	-- hashExpr
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cmpName :: Name -> Name -> Ordering
cmpName n1 n2 = iBox (n_uniq n1) `compare` iBox (n_uniq n2)
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stableNameCmp :: Name -> Name -> Ordering
-- Compare lexicographically
stableNameCmp (Name { n_sort = s1, n_occ = occ1 })
	      (Name { n_sort = s2, n_occ = occ2 })
  = (s1 `sort_cmp` s2) `thenCmp` (occ1 `compare` occ2)
    -- The ordinary compare on OccNames is lexicogrpahic
  where
    -- Later constructors are bigger
    sort_cmp (External m1) (External m2)       = m1 `stableModuleCmp` m2
    sort_cmp (External {}) _                   = LT
    sort_cmp (WiredIn {}) (External {})        = GT
    sort_cmp (WiredIn m1 _ _) (WiredIn m2 _ _) = m1 `stableModuleCmp` m2
    sort_cmp (WiredIn {})     _                = LT
    sort_cmp Internal         (External {})    = GT
    sort_cmp Internal         (WiredIn {})     = GT
    sort_cmp Internal         Internal         = EQ
    sort_cmp Internal         System           = LT
    sort_cmp System           System           = EQ
    sort_cmp System           _                = GT
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\end{code}
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%************************************************************************
%*									*
\subsection[Name-instances]{Instance declarations}
%*									*
%************************************************************************

\begin{code}
instance Eq Name where
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    a == b = case (a `compare` b) of { EQ -> True;  _ -> False }
    a /= b = case (a `compare` b) of { EQ -> False; _ -> True }
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instance Ord Name where
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    a <= b = case (a `compare` b) of { LT -> True;  EQ -> True;  GT -> False }
    a <	 b = case (a `compare` b) of { LT -> True;  EQ -> False; GT -> False }
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    a >= b = case (a `compare` b) of { LT -> False; EQ -> True;  GT -> True  }
    a >	 b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True  }
    compare a b = cmpName a b
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instance Uniquable Name where
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    getUnique = nameUnique
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instance NamedThing Name where
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    getName n = n
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instance Data Name where
  -- don't traverse?
  toConstr _   = abstractConstr "Name"
  gunfold _ _  = error "gunfold"
  dataTypeOf _ = mkNoRepType "Name"
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\end{code}

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%************************************************************************
%*									*
\subsection{Binary}
%*									*
%************************************************************************

\begin{code}
instance Binary Name where
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   put_ bh name =
      case getUserData bh of 
        UserData{ ud_put_name = put_name } -> put_name bh name
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   get bh =
      case getUserData bh of
        UserData { ud_get_name = get_name } -> get_name bh
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\end{code}
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%************************************************************************
%*									*
\subsection{Pretty printing}
%*									*
%************************************************************************
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\begin{code}
instance Outputable Name where
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    ppr name = pprName name

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instance OutputableBndr Name where
    pprBndr _ name = pprName name
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    pprInfixOcc  = pprInfixName
    pprPrefixOcc = pprPrefixName

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pprName :: Name -> SDoc
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pprName n@(Name {n_sort = sort, n_uniq = u, n_occ = occ})
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  = getPprStyle $ \ sty ->
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    case sort of
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      WiredIn mod _ builtin   -> pprExternal sty uniq mod occ n True  builtin
      External mod            -> pprExternal sty uniq mod occ n False UserSyntax
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      System   		      -> pprSystem sty uniq occ
      Internal    	      -> pprInternal sty uniq occ
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  where uniq = mkUniqueGrimily (iBox u)
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pprExternal :: PprStyle -> Unique -> Module -> OccName -> Name -> Bool -> BuiltInSyntax -> SDoc
pprExternal sty uniq mod occ name is_wired is_builtin
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  | codeStyle sty = ppr mod <> char '_' <> ppr_z_occ_name occ
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	-- In code style, always qualify
	-- ToDo: maybe we could print all wired-in things unqualified
	-- 	 in code style, to reduce symbol table bloat?
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  | debugStyle sty = pp_mod <> ppr_occ_name occ
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		     <> braces (hsep [if is_wired then ptext (sLit "(w)") else empty,
				      pprNameSpaceBrief (occNameSpace occ), 
		 		      pprUnique uniq])
  | BuiltInSyntax <- is_builtin = ppr_occ_name occ  -- Never qualify builtin syntax
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  | otherwise                   = pprModulePrefix sty mod name <> ppr_occ_name occ
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  where
    pp_mod | opt_SuppressModulePrefixes = empty
           | otherwise                  = ppr mod <> dot 
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pprInternal :: PprStyle -> Unique -> OccName -> SDoc
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pprInternal sty uniq occ
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  | codeStyle sty  = pprUnique uniq
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  | debugStyle sty = ppr_occ_name occ <> braces (hsep [pprNameSpaceBrief (occNameSpace occ), 
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				 		       pprUnique uniq])
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  | dumpStyle sty  = ppr_occ_name occ <> ppr_underscore_unique uniq
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			-- For debug dumps, we're not necessarily dumping
			-- tidied code, so we need to print the uniques.
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  | otherwise      = ppr_occ_name occ	-- User style
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-- Like Internal, except that we only omit the unique in Iface style
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pprSystem :: PprStyle -> Unique -> OccName -> SDoc
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pprSystem sty uniq occ
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  | codeStyle sty  = pprUnique uniq
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  | debugStyle sty = ppr_occ_name occ <> ppr_underscore_unique uniq
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		     <> braces (pprNameSpaceBrief (occNameSpace occ))
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  | otherwise	   = ppr_occ_name occ <> ppr_underscore_unique uniq
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				-- If the tidy phase hasn't run, the OccName
				-- is unlikely to be informative (like 's'),
				-- so print the unique
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pprModulePrefix :: PprStyle -> Module -> Name -> SDoc
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-- Print the "M." part of a name, based on whether it's in scope or not
-- See Note [Printing original names] in HscTypes
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pprModulePrefix sty mod name
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  | opt_SuppressModulePrefixes = empty
  
  | otherwise
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  = case qualName sty name of              -- See Outputable.QualifyName:
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      NameQual modname -> ppr modname <> dot       -- Name is in scope       
      NameNotInScope1  -> ppr mod <> dot           -- Not in scope
      NameNotInScope2  -> ppr (modulePackageId mod) <> colon     -- Module not in
                          <> ppr (moduleName mod) <> dot         -- scope eithber
      _otherwise       -> empty

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ppr_underscore_unique :: Unique -> SDoc
-- Print an underscore separating the name from its unique
-- But suppress it if we aren't printing the uniques anyway
ppr_underscore_unique uniq
  | opt_SuppressUniques = empty
  | otherwise		= char '_' <> pprUnique uniq

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ppr_occ_name :: OccName -> SDoc
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ppr_occ_name occ = ftext (occNameFS occ)
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	-- Don't use pprOccName; instead, just print the string of the OccName; 
	-- we print the namespace in the debug stuff above
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-- In code style, we Z-encode the strings.  The results of Z-encoding each FastString are
-- cached behind the scenes in the FastString implementation.
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ppr_z_occ_name :: OccName -> SDoc
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ppr_z_occ_name occ = ftext (zEncodeFS (occNameFS occ))
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-- Prints (if mod information is available) "Defined at <loc>" or 
--  "Defined in <mod>" information for a Name.
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pprDefinedAt :: Name -> SDoc
pprDefinedAt name = ptext (sLit "Defined") <+> pprNameDefnLoc name

pprNameDefnLoc :: Name -> SDoc
-- Prints "at <loc>" or 
--     or "in <mod>" depending on what info is available
pprNameDefnLoc name 
  = case nameSrcLoc name of
         -- nameSrcLoc rather than nameSrcSpan
	 -- It seems less cluttered to show a location
	 -- rather than a span for the definition point
       RealSrcLoc s -> ptext (sLit "at") <+> ppr s
       UnhelpfulLoc s
         | isInternalName name || isSystemName name
         -> ptext (sLit "at") <+> ftext s
         | otherwise 
         -> ptext (sLit "in") <+> quotes (ppr (nameModule name))
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\end{code}
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%************************************************************************
%*									*
\subsection{Overloaded functions related to Names}
%*									*
%************************************************************************

\begin{code}
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-- | A class allowing convenient access to the 'Name' of various datatypes
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class NamedThing a where
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    getOccName :: a -> OccName
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    getName    :: a -> Name

    getOccName n = nameOccName (getName n)	-- Default method
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\end{code}

\begin{code}
getSrcLoc	    :: NamedThing a => a -> SrcLoc
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getSrcSpan	    :: NamedThing a => a -> SrcSpan
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getOccString	    :: NamedThing a => a -> String
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getSrcLoc	    = nameSrcLoc	   . getName
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getSrcSpan	    = nameSrcSpan	   . getName
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getOccString 	    = occNameString	   . getOccName
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pprInfixName, pprPrefixName :: (Outputable a, NamedThing a) => a -> SDoc
-- See Outputable.pprPrefixVar, pprInfixVar; 
-- add parens or back-quotes as appropriate
pprInfixName  n = pprInfixVar  (isSymOcc (getOccName n)) (ppr n)
pprPrefixName n = pprPrefixVar (isSymOcc (getOccName n)) (ppr n)
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\end{code}