[project @ 2004-04-05 10:52:23 by simonpj]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcGenDeriv.lhs

diff --git a/ghc/compiler/typecheck/TcGenDeriv.lhs b/ghc/compiler/typecheck/TcGenDeriv.lhs
index 9796387..67cb7ee 100644 (file)
--- a/ghc/compiler/typecheck/TcGenDeriv.lhs
+++ b/ghc/compiler/typecheck/TcGenDeriv.lhs
@@ -164,7 +164,7 @@ gen_Eq_binds tycon
                case maybeTyConSingleCon tycon of
                  Just _ -> []
                  Nothing -> -- if cons don't match, then False
-                    [([wildPat, wildPat], false_Expr)]
+                    [([nlWildPat, nlWildPat], false_Expr)]
            else -- calc. and compare the tags
                 [([a_Pat, b_Pat],
                    untag_Expr tycon [(a_RDR,ah_RDR), (b_RDR,bh_RDR)]
@@ -329,13 +329,13 @@ gen_Ord_binds tycon
                           -- Catch this specially to avoid warnings
                           -- about overlapping patterns from the desugarer,
                           -- and to avoid unnecessary pattern-matching
-      = [([wildPat,wildPat], eqTag_Expr)]
+      = [([nlWildPat,nlWildPat], eqTag_Expr)]
       | otherwise
       = map pats_etc nonnullary_cons ++
        (if single_con_type then        -- Omit wildcards when there's just one 
              []                        -- constructor, to silence desugarer
        else
-              [([wildPat, wildPat], default_rhs)])
+              [([nlWildPat, nlWildPat], default_rhs)])
 
       where
        pats_etc data_con
@@ -597,7 +597,7 @@ gen_Ix_binds tycon
     enum_index
       = mk_easy_FunBind tycon_loc index_RDR 
                [noLoc (AsPat (noLoc c_RDR) 
-                          (nlTuplePat [a_Pat, wildPat] Boxed)), 
+                          (nlTuplePat [a_Pat, nlWildPat] Boxed)), 
                                d_Pat] emptyBag (
        nlHsIf (nlHsPar (nlHsVarApps inRange_RDR [c_RDR, d_RDR])) (
           untag_Expr tycon [(a_RDR, ah_RDR)] (
@@ -898,7 +898,7 @@ gen_Show_binds get_fixity tycon
        pats_etc data_con
          | nullary_con =  -- skip the showParen junk...
             ASSERT(null bs_needed)
-            ([wildPat, con_pat], mk_showString_app con_str)
+            ([nlWildPat, con_pat], mk_showString_app con_str)
          | otherwise   =
             ([a_Pat, con_pat],
                  showParen_Expr (nlHsPar (genOpApp a_Expr ge_RDR (nlHsLit (HsInt con_prec_plus_one))))
@@ -994,7 +994,7 @@ From the data type
 we generate
 
        instance Typeable2 T where
-               typeOf2 _ = mkAppTy (mkTyConRep "T") []
+               typeOf2 _ = mkTyConApp (mkTyConRep "T") []
 
 We are passed the Typeable2 class as well as T
 
@@ -1004,7 +1004,7 @@ gen_Typeable_binds tycon
   = unitBag $
        mk_easy_FunBind tycon_loc 
                (mk_typeOf_RDR tycon)   -- Name of appropriate type0f function
-               [wildPat] emptyBag
+               [nlWildPat] emptyBag
                (nlHsApps mkTypeRep_RDR [tycon_rep, nlList []])
   where
     tycon_loc = getSrcSpan tycon
@@ -1042,11 +1042,11 @@ we generate
     gfoldl k z (T1 a b) = z T `k` a `k` b
     gfoldl k z T2          = z T2
     -- ToDo: add gmapT,Q,M, gfoldr
-    
-    fromConstr c = case conIndex c of
-                       I# 1# -> T1 undefined undefined
-                       I# 2# -> T2
-    
+ 
+    gunfold k z c = case conIndex c of
+                       I# 1# -> k (k (z T1))
+                       I# 2# -> z T2
+
     toConstr (T1 _ _) = $cT1
     toConstr T2              = $cT2
     
@@ -1058,13 +1058,15 @@ gen_Data_binds :: FixityEnv
               -> (LHsBinds RdrName,    -- The method bindings
                   LHsBinds RdrName)    -- Auxiliary bindings
 gen_Data_binds fix_env tycon
-  = (listToBag [gfoldl_bind, fromCon_bind, toCon_bind, dataTypeOf_bind],
+  = (listToBag [gfoldl_bind, gunfold_bind, toCon_bind, dataTypeOf_bind],
                -- Auxiliary definitions: the data type and constructors
      datatype_bind `consBag` listToBag (map mk_con_bind data_cons))
   where
-    tycon_loc = getSrcSpan tycon
+    tycon_loc  = getSrcSpan tycon
     tycon_name = tyConName tycon
-    data_cons = tyConDataCons tycon
+    data_cons  = tyConDataCons tycon
+    n_cons     = length data_cons
+    one_constr = n_cons == 1
 
        ------------ gfoldl
     gfoldl_bind = mk_FunBind tycon_loc gfoldl_RDR (map gfoldl_eqn data_cons)
@@ -1076,13 +1078,28 @@ gen_Data_binds fix_env tycon
                     as_needed = take (dataConSourceArity con) as_RDRs
                     mk_k_app e v = nlHsPar (nlHsOpApp e k_RDR (nlHsVar v))
 
-       ------------ fromConstr
-    fromCon_bind = mk_FunBind tycon_loc fromConstr_RDR [([c_Pat], from_con_rhs)]
-    from_con_rhs = nlHsCase (nlHsVar conIndex_RDR `nlHsApp` c_Expr) 
-                         (map from_con_alt data_cons)
-    from_con_alt dc = mkSimpleHsAlt (nlConPat intDataCon_RDR [nlLitPat (HsIntPrim (toInteger (dataConTag dc)))])
-                                   (nlHsVarApps (getRdrName dc)
-                                                (replicate (dataConSourceArity dc) undefined_RDR))
+       ------------ gunfold
+    gunfold_bind = mk_FunBind tycon_loc
+                              gunfold_RDR
+                              [([k_Pat, z_Pat, if one_constr then nlWildPat else c_Pat], 
+                               gunfold_rhs)]
+
+    gunfold_rhs 
+       | one_constr = mk_unfold_rhs (head data_cons)   -- No need for case
+       | otherwise  = nlHsCase (nlHsVar conIndex_RDR `nlHsApp` c_Expr) 
+                               (map gunfold_alt data_cons)
+
+    gunfold_alt dc = mkSimpleHsAlt (mk_unfold_pat dc) (mk_unfold_rhs dc)
+    mk_unfold_rhs dc = foldr nlHsApp
+                           (nlHsVar z_RDR `nlHsApp` nlHsVar (getRdrName dc))
+                           (replicate (dataConSourceArity dc) (nlHsVar k_RDR))
+
+    mk_unfold_pat dc   -- Last one is a wild-pat, to avoid 
+                       -- redundant test, and annoying warning
+      | tag-fIRST_TAG == n_cons-1 = nlWildPat  -- Last constructor
+      | otherwise = nlConPat intDataCon_RDR [nlLitPat (HsIntPrim (toInteger tag))]
+      where 
+       tag = dataConTag dc
                          
        ------------ toConstr
     toCon_bind = mk_FunBind tycon_loc toConstr_RDR (map to_con_eqn data_cons)
@@ -1092,7 +1109,7 @@ gen_Data_binds fix_env tycon
     dataTypeOf_bind = mk_easy_FunBind
                         tycon_loc
                         dataTypeOf_RDR
-                       [wildPat]
+                       [nlWildPat]
                         emptyBag
                         (nlHsVar data_type_name)
 
@@ -1130,7 +1147,7 @@ gen_Data_binds fix_env tycon
                 | otherwise = prefix_RDR
 
 gfoldl_RDR     = varQual_RDR gENERICS_Name FSLIT("gfoldl")
-fromConstr_RDR = varQual_RDR gENERICS_Name FSLIT("fromConstr")
+gunfold_RDR    = varQual_RDR gENERICS_Name FSLIT("gunfold")
 toConstr_RDR   = varQual_RDR gENERICS_Name FSLIT("toConstr")
 dataTypeOf_RDR = varQual_RDR gENERICS_Name FSLIT("dataTypeOf")
 mkConstr_RDR   = varQual_RDR gENERICS_Name FSLIT("mkConstr")
@@ -1437,6 +1454,8 @@ a_Pat             = nlVarPat a_RDR
 b_Pat          = nlVarPat b_RDR
 c_Pat          = nlVarPat c_RDR
 d_Pat          = nlVarPat d_RDR
+k_Pat          = nlVarPat k_RDR
+z_Pat          = nlVarPat z_RDR
 
 con2tag_RDR, tag2con_RDR, maxtag_RDR :: TyCon ->  RdrName
 -- Generates Orig s RdrName, for the binding positions