prelude/PrelInfo.lhs

% % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[PrelInfo]{The @PrelInfo@ interface to the compiler's prelude knowledge} \begin{code}

    {-# 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 PrelInfo (
            wiredInIds, ghcPrimIds,
            primOpRules, builtinRules,

            ghcPrimExports,
            wiredInThings, basicKnownKeyNames,
            primOpId,

            -- Random other things
            maybeCharLikeCon, maybeIntLikeCon,

            -- Class categories
            isNumericClass, isStandardClass

        ) where

    #include "HsVersions.h"

    import PrelNames
    import PrelRules
    import Avail
    import PrimOp
    import DataCon
    import Id
    import MkId
    import TysPrim
    import TysWiredIn
    import HscTypes
    import Class
    import TyCon
    import Util
    import {-# SOURCE #-} TcTypeNats ( typeNatTyCons )

    import Data.Array

\end{code} %************************************************************************ %* * \subsection[builtinNameInfo]{Lookup built-in names} %* * %************************************************************************ Notes about wired in things ~~~~~~~~~~~~~~~~~~~~~~~~~~~ * Wired-in things are Ids\/TyCons that are completely known to the compiler. They are global values in GHC, (e.g. listTyCon :: TyCon). * A wired in Name contains the thing itself inside the Name: see Name.wiredInNameTyThing_maybe (E.g. listTyConName contains listTyCon. * The name cache is initialised with (the names of) all wired-in things * The type checker sees if the Name is wired in before looking up the name in the type environment. So the type envt itself contains no wired in things. * MkIface prunes out wired-in things before putting them in an interface file. So interface files never contain wired-in things. \begin{code}

    wiredInThings :: [TyThing]
    -- This list is used only to initialise HscMain.knownKeyNames
    -- to ensure that when you say "Prelude.map" in your source code, you
    -- get a Name with the correct known key (See Note [Known-key names])
    wiredInThings
      = concat
        [		-- Wired in TyCons and their implicit Ids
    	  tycon_things
    	, concatMap implicitTyThings tycon_things

    		-- Wired in Ids
    	, map AnId wiredInIds

    		-- PrimOps
    	, map (AnId . primOpId) allThePrimOps
        ]
      where
        tycon_things = map ATyCon ([funTyCon] ++ primTyCons ++ wiredInTyCons
                                        ++ typeNatTyCons)

\end{code} We let a lot of "non-standard" values be visible, so that we can make sense of them in interface pragmas. It's cool, though they all have "non-standard" names, so they won't get past the parser in user code. %************************************************************************ %* * PrimOpIds %* * %************************************************************************ \begin{code}

    primOpIds :: Array Int Id
    -- A cache of the PrimOp Ids, indexed by PrimOp tag
    primOpIds = array (1,maxPrimOpTag) [ (primOpTag op, mkPrimOpId op)
    				   | op <- allThePrimOps ]

    primOpId :: PrimOp -> Id
    primOpId op = primOpIds ! primOpTag op

\end{code} %************************************************************************ %* * \subsection{Export lists for pseudo-modules (GHC.Prim)} %* * %************************************************************************ GHC.Prim "exports" all the primops and primitive types, some wired-in Ids. \begin{code}

    ghcPrimExports :: [IfaceExport]
    ghcPrimExports
     = map (Avail . idName) ghcPrimIds ++
       map (Avail . idName . primOpId) allThePrimOps ++
       [ AvailTC n [n]
       | tc <- funTyCon : coercibleTyCon : primTyCons, let n = tyConName tc  ]

\end{code} %************************************************************************ %* * \subsection{Built-in keys} %* * %************************************************************************ ToDo: make it do the ``like'' part properly (as in 0.26 and before). \begin{code}

    maybeCharLikeCon, maybeIntLikeCon :: DataCon -> Bool
    maybeCharLikeCon con = con `hasKey` charDataConKey
    maybeIntLikeCon  con = con `hasKey` intDataConKey

\end{code} %************************************************************************ %* * \subsection{Class predicates} %* * %************************************************************************ \begin{code}

    isNumericClass, isStandardClass :: Class -> Bool

    isNumericClass     clas = classKey clas `is_elem` numericClassKeys
    isStandardClass    clas = classKey clas `is_elem` standardClassKeys

    is_elem :: Eq a => a -> [a] -> Bool
    is_elem = isIn "is_X_Class"

\end{code}