[project @ 1996-05-17 16:02:43 by partain]

[ghc-hetmet.git] / ghc / compiler / deSugar / DsUtils.lhs

diff --git a/ghc/compiler/deSugar/DsUtils.lhs b/ghc/compiler/deSugar/DsUtils.lhs
index eeb8f26..5790628 100644 (file)
--- a/ghc/compiler/deSugar/DsUtils.lhs
+++ b/ghc/compiler/deSugar/DsUtils.lhs
@@ -40,26 +40,24 @@ import DsMonad
 
 import CoreUtils       ( coreExprType, mkCoreIfThenElse )
 import PprStyle                ( PprStyle(..) )
-import PrelInfo                ( stringTy, iRREFUT_PAT_ERROR_ID )
+import PrelVals                ( iRREFUT_PAT_ERROR_ID )
 import Pretty          ( ppShow )
 import Id              ( idType, dataConArgTys, mkTupleCon,
                          pprId{-ToDo:rm-},
                          DataCon(..), DictVar(..), Id(..), GenId )
 import Literal         ( Literal(..) )
-import TyCon           ( mkTupleTyCon )
+import TyCon           ( mkTupleTyCon, isNewTyCon, tyConDataCons )
 import Type            ( mkTyVarTys, mkRhoTy, mkForAllTys, mkFunTys,
-                         isUnboxedType, applyTyCon, getAppDataTyCon
+                         mkTheta, isUnboxedType, applyTyCon, getAppTyCon
                        )
 import UniqSet         ( mkUniqSet, minusUniqSet, uniqSetToList, UniqSet(..) )
 import Util            ( panic, assertPanic, pprTrace{-ToDo:rm-} )
 import PprCore{-ToDo:rm-}
-import PprType--ToDo:rm
+--import PprType--ToDo:rm
 import Pretty--ToDo:rm
 import TyVar--ToDo:rm
 import Unique--ToDo:rm
 import Usage--ToDo:rm
-
-splitDictType = panic "DsUtils.splitDictType"
 \end{code}
 
 %************************************************************************
@@ -138,6 +136,11 @@ mkCoAlgCaseMatchResult :: Id                               -- Scrutinee
                    -> DsM MatchResult
 
 mkCoAlgCaseMatchResult var alts
+  | isNewTyCon tycon           -- newtype case; use a let
+  = ASSERT( newtype_sanity )
+    returnDs (mkCoLetsMatchResult [coercion_bind] match_result)
+
+  | otherwise                  -- datatype case  
   =        -- Find all the constructors in the type which aren't
            -- explicitly mentioned in the alternatives:
     case un_mentioned_constructors of
@@ -171,8 +174,21 @@ mkCoAlgCaseMatchResult var alts
                                      (mk_case alts (\fail_expr -> BindDefault wild fail_expr))
                                      cxt1)
   where
+       -- Common stuff
     scrut_ty = idType var
-    (tycon, tycon_arg_tys, data_cons) = pprTrace "CoAlgCase:" (pprType PprDebug scrut_ty) $ getAppDataTyCon scrut_ty
+    (tycon, tycon_arg_tys) = --pprTrace "CoAlgCase:" (pprType PprDebug scrut_ty) $ 
+                            getAppTyCon scrut_ty
+
+       -- Stuff for newtype
+    (con_id, arg_ids, match_result) = head alts
+    arg_id                         = head arg_ids
+    coercion_bind                  = NonRec arg_id (Coerce (CoerceOut con_id) 
+                                                           (idType arg_id)
+                                                           (Var var))
+    newtype_sanity                 = null (tail alts) && null (tail arg_ids)
+
+       -- Stuff for data types
+    data_cons = tyConDataCons tycon
 
     un_mentioned_constructors
       = uniqSetToList (mkUniqSet data_cons `minusUniqSet` mkUniqSet [ con | (con, _, _) <- alts] )
@@ -403,7 +419,7 @@ The general case:
 
 \begin{code}
 mkTupleBind tyvars dicts local_global_prs tuple_expr
-  = pprTrace "mkTupleBind:\n" (ppAboves [ppCat (map (pprId PprShowAll) locals), ppCat (map (pprId PprShowAll) globals), {-ppr PprDebug local_tuple, pprType PprDebug res_ty,-} ppr PprDebug tuple_expr]) $
+  = --pprTrace "mkTupleBind:\n" (ppAboves [ppCat (map (pprId PprShowAll) locals), ppCat (map (pprId PprShowAll) globals), {-ppr PprDebug local_tuple, pprType PprDebug res_ty,-} ppr PprDebug tuple_expr]) $
 
     newSysLocalDs tuple_var_ty `thenDs` \ tuple_var ->
 
@@ -430,7 +446,7 @@ mkTupleBind tyvars dicts local_global_prs tuple_expr
        applyTyCon (mkTupleTyCon no_of_binders)
                   (map idType locals)
       where
-       theta = map (splitDictType . idType) dicts
+       theta = mkTheta (map idType dicts)
 
     mk_selector :: CoreExpr -> (Id, Id) -> Int -> DsM (Id, CoreExpr)