X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FbasicTypes%2FDataCon.lhs;h=0c6e3c57200d8f94c9e6d1691100b38af8875de3;hp=851bf661da52d639a68ea60a66e7ed5d89aedf6b;hb=6a05ec5ef5373f61b7f9f5bdc344483417fa801b;hpb=6202305819577fce2b11ab509ed94422775df30e;ds=sidebyside

diff --git a/compiler/basicTypes/DataCon.lhs b/compiler/basicTypes/DataCon.lhs
index 851bf66..0c6e3c5 100644
--- a/compiler/basicTypes/DataCon.lhs
+++ b/compiler/basicTypes/DataCon.lhs
@@ -87,15 +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).
@@ -129,6 +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)
@@ -152,6 +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