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[ghc-hetmet.git] / compiler / basicTypes / DataCon.lhs

diff --git a/compiler/basicTypes/DataCon.lhs b/compiler/basicTypes/DataCon.lhs
index 2c4400b..0c6e3c5 100644 (file)
--- a/compiler/basicTypes/DataCon.lhs
+++ b/compiler/basicTypes/DataCon.lhs
@@ -44,7 +44,6 @@ import ListSetOps
 import Util
 import Maybes
 import FastString
-import PackageConfig
 import Module
 
 import Data.Char
@@ -88,15 +87,20 @@ differently, as follows.
 
 Note [Data Constructor Naming]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Each data constructor C has two, and possibly three, Names associated with it:
+Each data constructor C has two, and possibly up to four, Names associated with it:
 
-                            OccName    Name space      Used for
+                            OccName    Name space      Name of
   ---------------------------------------------------------------------------
-  * The "source data con"      C       DataName        The DataCon itself
-  * The "real data con"                C       VarName         Its worker Id
-  * The "wrapper data con"     $WC     VarName         Wrapper Id (optional)
-
-Each of these three has a distinct Unique.  The "source data con" name
+  * The "data con itself"      C       DataName        DataCon
+  * The "worker data con"      C       VarName         Id (the worker)
+  * The "wrapper data con"     $WC     VarName         Id (the wrapper)
+  * The "newtype coercion"      :CoT    TcClsName      TyCon
+ 
+EVERY data constructor (incl for newtypes) has the former two (the
+data con itself, and its worker.  But only some data constructors have a
+wrapper (see Note [The need for a wrapper]).
+
+Each of these three has a distinct Unique.  The "data con itself" name
 appears in the output of the renamer, and names the Haskell-source
 data constructor.  The type checker translates it into either the wrapper Id
 (if it exists) or worker Id (otherwise).
@@ -130,6 +134,8 @@ The "wrapper Id", $WC, goes as follows
   nothing for the wrapper to do.  That is, if its defn would be
        $wC = C
 
+Note [The need for a wrapper]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Why might the wrapper have anything to do?  Two reasons:
 
 * Unboxing strict fields (with -funbox-strict-fields)
@@ -153,6 +159,8 @@ Why might the wrapper have anything to do?  Two reasons:
   The third argument is a coerion
        [a] :: [a]:=:[a]
 
+INVARIANT: the dictionary constructor for a class
+          never has a wrapper.
 
 
 A note about the stupid context
@@ -525,6 +533,7 @@ mkDataCon name declared_infix
 eqSpecPreds :: [(TyVar,Type)] -> ThetaType
 eqSpecPreds spec = [ mkEqPred (mkTyVarTy tv, ty) | (tv,ty) <- spec ]
 
+mk_dict_strict_mark :: PredType -> StrictnessMark
 mk_dict_strict_mark pred | isStrictPred pred = MarkedStrict
                         | otherwise         = NotMarkedStrict
 \end{code}
@@ -608,6 +617,7 @@ dataConSourceArity dc = length (dcOrigArgTys dc)
 -- {\em representation} of the data constructor.  This may be more than appear
 -- in the source code; the extra ones are the existentially quantified
 -- dictionaries
+dataConRepArity :: DataCon -> Int
 dataConRepArity (MkData {dcRepArgTys = arg_tys}) = length arg_tys
 
 isNullarySrcDataCon, isNullaryRepDataCon :: DataCon -> Bool
@@ -784,14 +794,16 @@ splitProductType_maybe ty
           where
              data_con = ASSERT( not (null (tyConDataCons tycon)) ) 
                         head (tyConDataCons tycon)
-       other -> Nothing
+       _other -> Nothing
 
+splitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type])
 splitProductType str ty
   = case splitProductType_maybe ty of
        Just stuff -> stuff
        Nothing    -> pprPanic (str ++ ": not a product") (pprType ty)
 
 
+deepSplitProductType_maybe :: Type -> Maybe (TyCon, [Type], DataCon, [Type])
 deepSplitProductType_maybe ty
   = do { (res@(tycon, tycon_args, _, _)) <- splitProductType_maybe ty
        ; let {result 
@@ -804,6 +816,7 @@ deepSplitProductType_maybe ty
        ; result
        }
           
+deepSplitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type])
 deepSplitProductType str ty 
   = case deepSplitProductType_maybe ty of
       Just stuff -> stuff