[project @ 2004-04-05 10:35:11 by simonpj]

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

diff --git a/ghc/compiler/typecheck/TcTyDecls.lhs b/ghc/compiler/typecheck/TcTyDecls.lhs
index 824e95c..1501d56 100644 (file)
--- a/ghc/compiler/typecheck/TcTyDecls.lhs
+++ b/ghc/compiler/typecheck/TcTyDecls.lhs
@@ -13,21 +13,20 @@ files for imported data types.
 \begin{code}
 module TcTyDecls(
         calcTyConArgVrcs,
-       calcRecFlags, calcCycleErrs,
-       newTyConRhs
+       calcRecFlags, 
+       calcClassCycles, calcSynCycles
     ) where
 
 #include "HsVersions.h"
 
 import TypeRep          ( Type(..), TyNote(..), PredType(..) )  -- friend
-import HsSyn           ( TyClDecl(..), HsPred(..), LTyClDecl )
+import HsSyn           ( TyClDecl(..), HsPred(..), LTyClDecl, isClassDecl )
 import RnHsSyn         ( extractHsTyNames )
 import Type            ( predTypeRep )
-import BuildTyCl       ( newTyConRhs )
 import HscTypes                ( TyThing(..) )
 import TyCon            ( TyCon, ArgVrcs, tyConArity, tyConDataCons, tyConTyVars,
                           getSynTyConDefn, isSynTyCon, isAlgTyCon, isHiBootTyCon,
-                         tyConName, isNewTyCon, isProductTyCon, tyConArgVrcs )
+                         tyConName, isNewTyCon, isProductTyCon, tyConArgVrcs, newTyConRhs )
 import Class           ( classTyCon )
 import DataCon          ( dataConRepArgTys, dataConOrigArgTys )
 import Var              ( TyVar )
@@ -37,7 +36,7 @@ import NameEnv
 import NameSet
 import Digraph                 ( SCC(..), stronglyConnComp, stronglyConnCompR )
 import BasicTypes      ( RecFlag(..) )
-import SrcLoc          ( Located(..) )
+import SrcLoc          ( Located(..), unLoc )
 import Outputable
 \end{code}
 
@@ -107,23 +106,25 @@ synTyConsOfType ty
 ---------------------------------------- END NOTE ]
 
 \begin{code}
-calcCycleErrs :: [LTyClDecl Name] -> ([[Name]],        -- Recursive type synonym groups
-                                    [[Name]])  -- Ditto classes
-calcCycleErrs decls
-  = (findCyclics syn_edges, findCyclics cls_edges)
+calcSynCycles :: [LTyClDecl Name] -> [SCC (LTyClDecl Name)]
+calcSynCycles decls
+  = stronglyConnComp syn_edges
   where
-       --------------- Type synonyms ----------------------
-    syn_edges       = [ (name, mk_syn_edges rhs) | 
-                         L _ (TySynonym { tcdLName  = L _ name, 
-                                          tcdSynRhs = rhs }) <- decls ]
+    syn_edges = [ (ldecl, unLoc (tcdLName decl), 
+                         mk_syn_edges (tcdSynRhs decl))
+               | ldecl@(L _ decl) <- decls ]
 
     mk_syn_edges rhs = [ tc | tc <- nameSetToList (extractHsTyNames rhs), 
                              not (isTyVarName tc) ]
 
-       --------------- Classes ----------------------
-    cls_edges = [ (name, mk_cls_edges ctxt) | 
-                 L _ (ClassDecl { tcdLName = L _ name, 
-                                  tcdCtxt  = L _ ctxt }) <- decls ]
+
+calcClassCycles :: [LTyClDecl Name] -> [[LTyClDecl Name]]
+calcClassCycles decls
+  = [decls | CyclicSCC decls <- stronglyConnComp cls_edges]
+  where
+    cls_edges = [ (ldecl, unLoc (tcdLName decl),       
+                         mk_cls_edges (unLoc (tcdCtxt decl)))
+               | ldecl@(L _ decl) <- decls, isClassDecl decl ]
 
     mk_cls_edges ctxt = [ cls | L _ (HsClassP cls _) <- ctxt ]
 \end{code}
@@ -216,7 +217,7 @@ calcRecFlags tyclss
     nt_edges = [(t, mk_nt_edges t) | t <- new_tycons]
 
     mk_nt_edges nt     -- Invariant: nt is a newtype
-       = concatMap (mk_nt_edges1 nt) (tcTyConsOfType (newTyConRhs nt))
+       = concatMap (mk_nt_edges1 nt) (tcTyConsOfType (new_tc_rhs nt))
                        -- tyConsOfType looks through synonyms
 
     mk_nt_edges1 nt tc 
@@ -244,13 +245,15 @@ calcRecFlags tyclss
        | tc `elem` prod_tycons   = [tc]                -- Local product
        | tc `elem` new_tycons    = if is_rec_nt tc     -- Local newtype
                                    then []
-                                   else mk_prod_edges1 ptc (newTyConRhs tc)
+                                   else mk_prod_edges1 ptc (new_tc_rhs tc)
        | isHiBootTyCon tc        = [ptc]       -- Make it self-recursive if 
                                                -- it mentions an hi-boot TyCon
                -- At this point we know that either it's a local non-product data type,
                -- or it's imported.  Either way, it can't form part of a cycle
        | otherwise = []
                        
+new_tc_rhs tc = snd (newTyConRhs tc)   -- Ignore the type variables
+
 getTyCon (ATyCon tc) = tc
 getTyCon (AClass cl) = classTyCon cl
 
@@ -262,12 +265,6 @@ findLoopBreakers deps
     go edges = [ name
               | CyclicSCC ((tc,_,_) : edges') <- stronglyConnCompR edges,
                 name <- tyConName tc : go edges']
-
-findCyclics :: [(Name,[Name])] -> [[Name]]
-findCyclics deps
-  = [names | CyclicSCC names <- stronglyConnComp edges]
-  where
-    edges = [(name,name,ds) | (name,ds) <- deps]
 \end{code}
 
 These two functions know about type representations, so they could be