Straightened out implicit coercions for indexed types

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

diff --git a/compiler/typecheck/TcTyClsDecls.lhs b/compiler/typecheck/TcTyClsDecls.lhs
index e83d77f..9065d28 100644 (file)
--- a/compiler/typecheck/TcTyClsDecls.lhs
+++ b/compiler/typecheck/TcTyClsDecls.lhs
@@ -51,7 +51,8 @@ import TyCon          ( TyCon, AlgTyConRhs( AbstractTyCon, OpenDataTyCon,
                          tyConDataCons, mkForeignTyCon, isProductTyCon,
                          isRecursiveTyCon, isOpenTyCon,
                          tyConStupidTheta, synTyConRhs, isSynTyCon, tyConName,
-                          isNewTyCon, tyConKind, setTyConArgPoss ) 
+                          isNewTyCon, isDataTyCon, tyConKind, 
+                         setTyConArgPoss )
 import DataCon         ( DataCon, dataConUserType, dataConName, 
                          dataConFieldLabels, dataConTyCon, dataConAllTyVars,
                          dataConFieldType, dataConResTys )
@@ -61,12 +62,12 @@ import Name         ( Name, getSrcLoc )
 import Outputable
 import Maybe           ( isJust, fromJust, isNothing, catMaybes )
 import Maybes          ( expectJust )
+import Monad           ( unless )
 import Unify           ( tcMatchTys, tcMatchTyX )
 import Util            ( zipLazy, isSingleton, notNull, sortLe )
 import List            ( partition, elemIndex )
 import SrcLoc          ( Located(..), unLoc, getLoc, srcLocSpan )
 import ListSetOps      ( equivClasses, minusList )
-import List            ( delete )
 import Digraph         ( SCC(..) )
 import DynFlags                ( DynFlag( Opt_GlasgowExts, Opt_Generics, 
                                        Opt_UnboxStrictFields ) )
@@ -270,8 +271,12 @@ tcIdxTyInstDecl1 :: TyClDecl Name
                 -> TcM (Maybe InstInfo, Maybe TyThing) -- Nothing if error
 
 tcIdxTyInstDecl1 (decl@TySynonym {})
-  = kcIdxTyPats decl $ \k_tvs k_typats resKind _ ->
-    do { -- (1) kind check the right hand side of the type equation
+  = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
+    do { -- check that the family declaration is for a synonym
+        unless (isSynTyCon family) $
+          addErr (wrongKindOfFamily family)
+
+       ; -- (1) kind check the right hand side of the type equation
        ; k_rhs <- kcCheckHsType (tcdSynRhs decl) resKind
 
          -- (2) type check type equation
@@ -287,7 +292,12 @@ tcIdxTyInstDecl1 (decl@TySynonym {})
 tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
                               tcdCons = cons})
   = kcIdxTyPats decl $ \k_tvs k_typats resKind family ->
-    do { -- (1) kind check the data declaration as usual
+    do { -- check that the family declaration is for the right kind
+        unless (new_or_data == NewType  && isNewTyCon  family ||
+                new_or_data == DataType && isDataTyCon family) $
+          addErr (wrongKindOfFamily family)
+
+       ; -- (1) kind check the data declaration as usual
        ; k_decl <- kcDataDecl decl k_tvs
        ; let k_ctxt = tcdCtxt k_decl
             k_cons = tcdCons k_decl
@@ -309,6 +319,7 @@ tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
        ; t_typats     <- mappM tcHsKindedType k_typats
        ; stupid_theta <- tcHsKindedContext k_ctxt
 
+       ; index <- nextDFunIndex                   -- to generate unique names
        ; tycon <- fixM (\ tycon -> do 
             { data_cons <- mappM (addLocM (tcConDecl unbox_strict new_or_data 
                                              tycon t_tvs))
@@ -320,7 +331,7 @@ tcIdxTyInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
                            ASSERT( isSingleton data_cons )
                            mkNewTyConRhs tc_name tycon (head data_cons)
             ; buildAlgTyCon tc_name t_tvs stupid_theta tc_rhs Recursive
-                            False h98_syntax (Just (family, t_typats))
+                            False h98_syntax (Just (family, t_typats, index))
                  -- We always assume that indexed types are recursive.  Why?
                  -- (1) Due to their open nature, we can never be sure that a
                  -- further instance might not introduce a new recursive
@@ -727,6 +738,9 @@ tcTyClDecl1 calc_isrec
                                ; tvs2' <- mappM tcLookupTyVar tvs2 ;
                                ; return (tvs1', tvs2') }
 
+    -- For each AT argument compute the position of the corresponding class
+    -- parameter in the class head.  This will later serve as a permutation
+    -- vector when checking the validity of instance declarations.
     setTyThingPoss [ATyCon tycon] atTyVars = 
       let classTyVars = hsLTyVarNames tvs
          poss        =   catMaybes 
@@ -736,8 +750,7 @@ tcTyClDecl1 calc_isrec
                     -- There will be no Nothing, as we already passed renaming
       in 
       ATyCon (setTyConArgPoss tycon poss)
-    setTyThingPoss _             _ = panic "setTyThingPoss"
-
+    setTyThingPoss _             _ = panic "TcTyClsDecls.setTyThingPoss"
 
 tcTyClDecl1 calc_isrec 
   (ForeignType {tcdLName = L _ tc_name, tcdExtName = tc_ext_name})
@@ -1164,7 +1177,16 @@ tooFewParmsErr tc_name
   = ptext SLIT("Indexed type instance has too few parameters:") <+> 
     quotes (ppr tc_name)
 
-badBootTyIdxDeclErr = ptext SLIT("Illegal indexed type instance in hs-boot file")
+badBootTyIdxDeclErr = 
+  ptext SLIT("Illegal indexed type instance in hs-boot file")
+
+wrongKindOfFamily family =
+  ptext SLIT("Wrong category of type instance; declaration was for a") <+>
+  kindOfFamily
+  where
+    kindOfFamily | isSynTyCon  family = ptext SLIT("type synonym")
+                | isDataTyCon family = ptext SLIT("data type")
+                | isNewTyCon  family = ptext SLIT("newtype")
 
 emptyConDeclsErr tycon
   = sep [quotes (ppr tycon) <+> ptext SLIT("has no constructors"),