X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FbasicTypes%2FDataCon.lhs;h=0fb7fae87bd61fd7f209d929dad180185620a178;hp=3de990512874051f580f4c7c54f216eefd284d91;hb=84923cc7de2a93c22a2f72daf9ac863959efae13;hpb=27897431cf24d4bde04b15947440c7205f2d703c

diff --git a/compiler/basicTypes/DataCon.lhs b/compiler/basicTypes/DataCon.lhs
index 3de9905..0fb7fae 100644
--- a/compiler/basicTypes/DataCon.lhs
+++ b/compiler/basicTypes/DataCon.lhs
@@ -1,4 +1,5 @@
 %
+% (c) The University of Glasgow 2006
 % (c) The GRASP/AQUA Project, Glasgow University, 1998
 %
 \section[DataCon]{@DataCon@: Data Constructors}
@@ -29,28 +30,18 @@ module DataCon (
 
 #include "HsVersions.h"
 
-import Type		( Type, ThetaType, 
-			  substTyWith, substTyVar, mkTopTvSubst, 
-			  mkForAllTys, mkFunTys, mkTyConApp, mkTyVarTy, mkTyVarTys, 
-			  splitTyConApp_maybe, newTyConInstRhs, 
-			  mkPredTys, isStrictPred, pprType, mkPredTy
-			)
-import Coercion		( isEqPred, mkEqPred )
-import TyCon		( TyCon, FieldLabel, tyConDataCons, 
-			  isProductTyCon, isTupleTyCon, isUnboxedTupleTyCon,
-                          isNewTyCon, isClosedNewTyCon, isRecursiveTyCon,
-                          tyConFamInst_maybe )
-import Class		( Class, classTyCon )
-import Name		( Name, NamedThing(..), nameUnique, mkSysTvName, mkSystemName )
-import Var		( TyVar, CoVar, Id, mkTyVar, tyVarKind, setVarUnique,
-                          mkCoVar )
-import BasicTypes	( Arity, StrictnessMark(..) )
+import Type
+import Coercion
+import TyCon
+import Class
+import Name
+import Var
+import BasicTypes
 import Outputable
-import Unique		( Unique, Uniquable(..) )
-import ListSetOps	( assoc, minusList )
-import Util		( zipEqual, zipWithEqual )
-import List		( partition )
-import Maybes           ( expectJust )
+import Unique
+import ListSetOps
+import Util
+import Maybes
 import FastString
 \end{code}
 
@@ -262,6 +253,9 @@ data DataCon
 		-- [This is a change (Oct05): previously, vanilla datacons guaranteed to
 		--  have the same type variables as their parent TyCon, but that seems ugly.]
 
+	-- INVARIANT: the UnivTyVars and ExTyVars all have distinct OccNames
+	-- Reason: less confusing, and easier to generate IfaceSyn
+
 	dcEqSpec :: [(TyVar,Type)],	-- Equalities derived from the result type, 
 					-- *as written by the programmer*
 		-- This field allows us to move conveniently between the two ways
@@ -315,6 +309,7 @@ data DataCon
 					-- and *including* existential dictionaries
 
 	dcRepStrictness :: [StrictnessMark],	-- One for each *representation* argument	
+		-- See also Note [Data-con worker strictness] in MkId.lhs
 
 	dcRepType   :: Type,	-- Type of the constructor
 				-- 	forall a x y. (a:=:(x,y), Ord x) => x -> y -> MkT a
@@ -445,15 +440,21 @@ mkDataCon name declared_infix
 	  eq_spec theta
 	  orig_arg_tys tycon
 	  stupid_theta ids
+-- Warning: mkDataCon is not a good place to check invariants. 
+-- If the programmer writes the wrong result type in the decl, thus:
+--	data T a where { MkT :: S }
+-- then it's possible that the univ_tvs may hit an assertion failure
+-- if you pull on univ_tvs.  This case is checked by checkValidDataCon,
+-- so the error is detected properly... it's just that asaertions here
+-- are a little dodgy.
+
   = ASSERT( not (any isEqPred theta) )
 	-- We don't currently allow any equality predicates on
 	-- a data constructor (apart from the GADT ones in eq_spec)
     con
   where
     is_vanilla = null ex_tvs && null eq_spec && null theta
-    con = ASSERT( is_vanilla || not (isNewTyCon tycon) )
-		-- Invariant: newtypes have a vanilla data-con
-     	  MkData {dcName = name, dcUnique = nameUnique name, 
+    con = MkData {dcName = name, dcUnique = nameUnique name, 
 		  dcVanilla = is_vanilla, dcInfix = declared_infix,
 	  	  dcUnivTyVars = univ_tvs, dcExTyVars = ex_tvs, 
 		  dcEqSpec = eq_spec, 
@@ -618,7 +619,7 @@ dataConUserType  (MkData { dcUnivTyVars = univ_tvs,
     mkFunTys (mkPredTys theta) $
     mkFunTys arg_tys $
     case tyConFamInst_maybe tycon of
-      Nothing             -> mkTyConApp tycon (map (substTyVar subst) univ_tvs)
+      Nothing             -> mkTyConApp tycon (substTyVars subst univ_tvs)
       Just (ftc, insttys) -> mkTyConApp ftc insttys	    -- data instance
   where
     subst = mkTopTvSubst eq_spec
@@ -753,6 +754,6 @@ computeRep stricts tys
     unbox MarkedStrict    ty = [(MarkedStrict,    ty)]
     unbox MarkedUnboxed   ty = zipEqual "computeRep" (dataConRepStrictness arg_dc) arg_tys
                                where
-                                 (tycon, tycon_args, arg_dc, arg_tys) 
+                                 (_tycon, _tycon_args, arg_dc, arg_tys) 
                                      = deepSplitProductType "unbox_strict_arg_ty" ty
 \end{code}