refactor GF.Infra.Modules for better error messages

src/compiler/GF/Compile/GrammarToPGF.hs

@@ -570,7 +570,7 @@ prTrace  tr n = trace (render (text "-- OBSERVE" <+> A.ppTerm Unqualified 0 tr <
 
 -- | this function finds out what modules are really needed in the canonical gr.
 -- its argument is typically a concrete module name
-requiredCanModules :: (Ord i, Show i) => Bool -> M.MGrammar i a -> i -> [i]
+requiredCanModules :: Bool -> M.MGrammar a -> Ident -> [Ident]
 requiredCanModules isSingle gr c = nub $ filter notReuse ops ++ exts where
   exts = M.allExtends gr c
   ops  = if isSingle 

src/compiler/GF/Compile/Rename.hs

@@ -57,7 +57,7 @@ renameModule ms (name,mo) = checkIn (text "renaming module" <+> ppIdent name) $
   js2    <- checkMap (renameInfo mo status) js1
   return (name, mo {opens = map forceQualif (opens mo), jments = js2})
 
-type Status = (StatusTree, [(OpenSpec Ident, StatusTree)])
+type Status = (StatusTree, [(OpenSpec, StatusTree)])
 
 type StatusTree = BinTree Ident StatusInfo
 
@@ -112,7 +112,7 @@ info2status mq (c,i) = case i of
   AnyInd False m -> maybe Cn (const (Q m)) mq
   _           -> maybe Cn  Q mq
 
-tree2status :: OpenSpec Ident -> BinTree Ident Info -> BinTree Ident StatusInfo
+tree2status :: OpenSpec -> BinTree Ident Info -> BinTree Ident StatusInfo
 tree2status o = case o of
   OSimple i   -> mapTree (info2status (Just i))
   OQualif i j -> mapTree (info2status (Just j))
@@ -127,7 +127,7 @@ buildStatus gr c mo = let mo' = self2status c mo in do
       then (emptyBinTree, reverse sts) -- the module itself does not define any names
       else (mo',reverse sts) -- so the empty ident is not needed
 
-modInfo2status :: (OpenSpec Ident,SourceModInfo) -> (OpenSpec Ident, StatusTree)
+modInfo2status :: (OpenSpec,SourceModInfo) -> (OpenSpec, StatusTree)
 modInfo2status (o,mo) = (o,tree2status o (jments mo))
 
 self2status :: Ident -> SourceModInfo -> StatusTree

src/compiler/GF/Grammar/Binary.hs

@@ -26,16 +26,16 @@ instance Binary Ident where
                 then return identW
                 else return (identC bs)
 
-instance (Ord i, Binary i, Binary a) => Binary (MGrammar i a) where
+instance Binary a => Binary (MGrammar a) where
   put (MGrammar ms) = put ms
   get               = fmap MGrammar get
 
-instance (Ord i, Binary i, Binary a) => Binary (ModInfo i a) where
+instance Binary a => Binary (ModInfo a) where
   put mi = do put (mtype mi,mstatus mi,flags mi,extend mi,mwith mi,opens mi,mexdeps mi,jments mi,positions mi)
   get    = do (mtype,mstatus,flags,extend,mwith,opens,med,jments,positions) <- get
               return (ModInfo mtype mstatus flags extend mwith opens med jments positions)
 
-instance (Binary i) => Binary (ModuleType i) where
+instance Binary ModuleType where
   put MTAbstract       = putWord8 0
   put MTResource       = putWord8 2
   put (MTConcrete i)   = putWord8 3 >> put i
@@ -50,7 +50,7 @@ instance (Binary i) => Binary (ModuleType i) where
              5 -> get >>= return . MTInstance
              _ -> decodingError
 
-instance (Binary i) => Binary (MInclude i) where
+instance Binary MInclude where
   put MIAll         = putWord8 0
   put (MIOnly xs)   = putWord8 1 >> put xs
   put (MIExcept xs) = putWord8 2 >> put xs
@@ -61,7 +61,7 @@ instance (Binary i) => Binary (MInclude i) where
              2 -> fmap MIExcept get
              _ -> decodingError
 
-instance Binary i => Binary (OpenSpec i) where
+instance Binary OpenSpec where
   put (OSimple i)   = putWord8 0 >> put i
   put (OQualif i j) = putWord8 1 >> put (i,j)
   get = do tag <- getWord8

src/compiler/GF/Grammar/Grammar.hs

@@ -53,11 +53,11 @@ import GF.Data.Operations
 import qualified Data.ByteString.Char8 as BS
 
 -- | grammar as presented to the compiler
-type SourceGrammar = MGrammar Ident Info
+type SourceGrammar = MGrammar Info
 
 emptySourceGrammar = MGrammar []
 
-type SourceModInfo = ModInfo Ident Info
+type SourceModInfo = ModInfo Info
 
 type SourceModule = (Ident, SourceModInfo)
 

src/compiler/GF/Grammar/Lookup.hs

@@ -55,7 +55,7 @@ lookupIdent c t =
     Ok v  -> return v
     Bad _ -> Bad ("unknown identifier" +++ showIdent c)
 
-lookupIdentInfo :: ModInfo Ident a -> Ident -> Err a
+lookupIdentInfo :: ModInfo a -> Ident -> Err a
 lookupIdentInfo mo i = lookupIdent i (jments mo)
 
 lookupResDef :: SourceGrammar -> Ident -> Ident -> Err Term

src/compiler/GF/Grammar/Parser.y

@@ -135,7 +135,7 @@ ComplMod
   : {- empty -}  { MSComplete   } 
   | 'incomplete' { MSIncomplete }
 
-ModType :: { (ModuleType Ident,Ident) }
+ModType :: { (ModuleType,Ident) }
 ModType
   : 'abstract'  Ident                    { (MTAbstract,      $2) } 
   | 'resource'  Ident                    { (MTResource,      $2) }
@@ -143,9 +143,9 @@ ModType
   | 'concrete'  Ident 'of' Ident         { (MTConcrete $4,   $2) }
   | 'instance'  Ident 'of' Ident         { (MTInstance $4,   $2) }
 
-ModHeaderBody :: { ( [(Ident,MInclude Ident)]
+ModHeaderBody :: { ( [(Ident,MInclude)]
-                   , Maybe (Ident,MInclude Ident,[(Ident,Ident)])
+                   , Maybe (Ident,MInclude,[(Ident,Ident)])
-                   , [OpenSpec Ident]
+                   , [OpenSpec]
                    ) }
 ModHeaderBody
   : ListIncluded '**' Included 'with' ListInst '**' ModOpen { ($1, Just (fst $3,snd $3,$5), $7) }
@@ -156,14 +156,14 @@ ModHeaderBody
   |                   Included 'with' ListInst              { ([], Just (fst $1,snd $1,$3), []) }
   |                                                 ModOpen { ([], Nothing,                 $1) }
 
-ModOpen :: { [OpenSpec Ident] }
+ModOpen :: { [OpenSpec] }
 ModOpen
   :                 { [] }
   | 'open' ListOpen { $2 }
 
-ModBody :: { ( [(Ident,MInclude Ident)]
+ModBody :: { ( [(Ident,MInclude)]
-             , Maybe (Ident,MInclude Ident,[(Ident,Ident)])
+             , Maybe (Ident,MInclude,[(Ident,Ident)])
-             , Maybe ([OpenSpec Ident],[(Ident,SrcSpan,Info)],Options)
+             , Maybe ([OpenSpec],[(Ident,SrcSpan,Info)],Options)
              ) }
 ModBody
   : ListIncluded '**' Included 'with' ListInst '**' ModContent  { ($1, Just (fst $3,snd $3,$5), Just $7) }
@@ -175,7 +175,7 @@ ModBody
   |                                                 ModContent  { ([], Nothing,                 Just $1) }
   | ModBody ';'                                                 { $1                                     }
 
-ModContent :: { ([OpenSpec Ident],[(Ident,SrcSpan,Info)],Options) }
+ModContent :: { ([OpenSpec],[(Ident,SrcSpan,Info)],Options) }
 ModContent
   :                      '{' ListTopDef '}' { ([],[d | Left ds <- $2, d <- ds],concatOptions [o | Right o <- $2]) }
   | 'open' ListOpen 'in' '{' ListTopDef '}' { ($2,[d | Left ds <- $5, d <- ds],concatOptions [o | Right o <- $5]) }
@@ -185,12 +185,12 @@ ListTopDef
   : {- empty -}       { []      } 
   | TopDef ListTopDef { $1 : $2 }
 
-ListOpen :: { [OpenSpec Ident] }
+ListOpen :: { [OpenSpec] }
 ListOpen
   : Open              { [$1]    }
   | Open ',' ListOpen { $1 : $3 }
 
-Open :: { OpenSpec Ident }
+Open :: { OpenSpec }
 Open
   : Ident                   { OSimple $1    }
   | '(' Ident '=' Ident ')' { OQualif $2 $4 }
@@ -204,12 +204,12 @@ Inst :: { (Ident,Ident) }
 Inst
   : '(' Ident '=' Ident ')' { ($2,$4) }
 
-ListIncluded :: { [(Ident,MInclude Ident)] }
+ListIncluded :: { [(Ident,MInclude)] }
 ListIncluded
   : Included                  { [$1]    }
   | Included ',' ListIncluded { $1 : $3 }
 
-Included :: { (Ident,MInclude Ident) }
+Included :: { (Ident,MInclude) }
 Included 
   : Ident                       { ($1,MIAll      ) } 
   | Ident     '[' ListIdent ']' { ($1,MIOnly   $3) }

src/compiler/GF/Grammar/Printer.hs

@@ -9,7 +9,6 @@
 
 module GF.Grammar.Printer
            ( TermPrintQual(..)
-           , ppIdent
            , ppLabel
            , ppModule
            , ppJudgement
@@ -256,8 +255,6 @@ ppDDecl q (_,id,typ)
   | id == identW = ppTerm q 6 typ
   | otherwise    = parens (ppIdent id <+> colon <+> ppTerm q 0 typ)
 
-ppIdent = text . showIdent
-
 ppQIdent q m id =
   case q of
     Qualified   -> ppIdent m <> char '.' <> ppIdent id

src/compiler/GF/Infra/Dependencies.hs

@@ -35,7 +35,7 @@ prDepGraph deps = unlines $ [
      "ed" -> "style = \"dotted\""
 
 data ModDeps = ModDeps {
-  modtype    :: ModuleType Ident,
+  modtype    :: ModuleType,
   ofs        :: [Ident],
   extendeds  :: [Ident], 
   openeds    :: [Ident],

src/compiler/GF/Infra/Ident.hs

@@ -13,7 +13,7 @@
 -----------------------------------------------------------------------------
 
 module GF.Infra.Ident (-- * Identifiers
-	      Ident(..), ident2bs, showIdent,
+	      Ident(..), ident2bs, showIdent, ppIdent,
 	      identC, identV, identA, identAV, identW,
 	      argIdent, varStr, varX, isWildIdent, varIndex,
 	      -- * refreshing identifiers
@@ -23,7 +23,7 @@ module GF.Infra.Ident (-- * Identifiers
 
 import GF.Data.Operations
 import qualified Data.ByteString.Char8 as BS
--- import Monad
+import Text.PrettyPrint
 
 
 -- | the constructors labelled /INTERNAL/ are
@@ -51,6 +51,9 @@ ident2bs i = case i of
 showIdent :: Ident -> String
 showIdent i = BS.unpack $! ident2bs i
 
+ppIdent :: Ident -> Doc
+ppIdent = text . showIdent
+
 identC :: BS.ByteString -> Ident
 identV :: BS.ByteString -> Int -> Ident
 identA :: BS.ByteString -> Int -> Ident

src/compiler/GF/Infra/Modules.hs

@@ -19,32 +19,32 @@
 -----------------------------------------------------------------------------
 
 module GF.Infra.Modules (
-		MGrammar(..), ModInfo(..), ModuleType(..),
+        MGrammar(..), ModInfo(..), ModuleType(..),
-		MInclude (..),
+        MInclude (..),
-		extends, isInherited,inheritAll, 
+        extends, isInherited,inheritAll, 
-                updateMGrammar, updateModule, replaceJudgements, addFlag,
+        updateMGrammar, updateModule, replaceJudgements, addFlag,
-		addOpenQualif, flagsModule, allFlags, mapModules,
+        addOpenQualif, flagsModule, allFlags, mapModules,
-		OpenSpec(..),
+        OpenSpec(..),
-		ModuleStatus(..),
+        ModuleStatus(..),
-		openedModule, depPathModule, allDepsModule, partOfGrammar,
+        openedModule, depPathModule, allDepsModule, partOfGrammar,
-		allExtends, allExtendSpecs, allExtendsPlus, allExtensions, 
+        allExtends, allExtendSpecs, allExtendsPlus, allExtensions, 
-                searchPathModule, addModule,
+        searchPathModule, addModule,
-		emptyMGrammar, emptyModInfo,
+        emptyMGrammar, emptyModInfo,
-		IdentM(..),
+        abstractOfConcrete, abstractModOfConcrete,
-		abstractOfConcrete, abstractModOfConcrete,
+        lookupModule, lookupModuleType, lookupInfo,
-		lookupModule, lookupModuleType, lookupInfo,
+        lookupPosition, ppPosition,
-                lookupPosition, ppPosition,
+        isModAbs, isModRes, isModCnc,
-		isModAbs, isModRes, isModCnc,
+        sameMType, isCompilableModule, isCompleteModule,
-		sameMType, isCompilableModule, isCompleteModule,
+        allAbstracts, greatestAbstract, allResources,
-		allAbstracts, greatestAbstract, allResources,
+        greatestResource, allConcretes, allConcreteModules
-		greatestResource, allConcretes, allConcreteModules
+        ) where
-	       ) where
 
 import GF.Infra.Ident
 import GF.Infra.Option
 import GF.Data.Operations
 
 import Data.List
+import qualified Data.Map as Map
 import Text.PrettyPrint
 
 -- AR 29/4/2003
@@ -53,95 +53,95 @@ import Text.PrettyPrint
 -- The parameters tell what kind of data is involved.
 -- Invariant: modules are stored in dependency order
 
-newtype MGrammar i a = MGrammar {modules :: [(i,ModInfo i a)]}
+newtype MGrammar a = MGrammar {modules :: [(Ident,ModInfo a)]}
   deriving Show
 
-data ModInfo i a = ModInfo {
+data ModInfo a = ModInfo {
-    mtype   :: ModuleType i ,
+    mtype   :: ModuleType,
-    mstatus :: ModuleStatus ,
+    mstatus :: ModuleStatus,
     flags   :: Options,
-    extend  :: [(i,MInclude i)],
+    extend  :: [(Ident,MInclude)],
-    mwith   :: Maybe (i,MInclude i,[(i,i)]),
+    mwith   :: Maybe (Ident,MInclude,[(Ident,Ident)]),
-    opens   :: [OpenSpec i] ,
+    opens   :: [OpenSpec],
-    mexdeps :: [i] ,
+    mexdeps :: [Ident],
-    jments  :: BinTree i a ,
+    jments  :: Map.Map Ident a,
-    positions :: BinTree i (String,(Int,Int)) -- file, first line, last line
+    positions :: Map.Map Ident (String,(Int,Int)) -- file, first line, last line
   }
   deriving Show
 
 -- | encoding the type of the module
-data ModuleType i = 
+data ModuleType = 
     MTAbstract 
   | MTResource
-  | MTConcrete i
+  | MTConcrete Ident
-    -- ^ up to this, also used in GFC. Below, source only.
+    -- ^ up to this, also used in GFO. Below, source only.
   | MTInterface
-  | MTInstance i 
+  | MTInstance Ident
-  deriving (Eq,Ord,Show)
+  deriving (Eq,Show)
 
-data MInclude i = MIAll | MIOnly [i] | MIExcept [i]
+data MInclude = MIAll | MIOnly [Ident] | MIExcept [Ident]
-  deriving (Eq,Ord,Show)
+  deriving (Eq,Show)
 
-extends :: ModInfo i a -> [i]
+extends :: ModInfo a -> [Ident]
 extends = map fst . extend
 
-isInherited :: Eq i => MInclude i -> i -> Bool
+isInherited :: MInclude -> Ident -> Bool
 isInherited c i = case c of
   MIAll -> True
   MIOnly is -> elem i is
   MIExcept is -> notElem i is
 
-inheritAll :: i -> (i,MInclude i)
+inheritAll :: Ident -> (Ident,MInclude)
 inheritAll i = (i,MIAll)
 
 -- destructive update
 
 -- | dep order preserved since old cannot depend on new
-updateMGrammar :: Ord i => MGrammar i a -> MGrammar i a -> MGrammar i a
+updateMGrammar :: MGrammar a -> MGrammar a -> MGrammar a
-updateMGrammar old new = MGrammar $ 
+updateMGrammar old new = MGrammar $
   [(i,m) | (i,m) <- os, notElem i (map fst ns)] ++ ns
  where
    os = modules old
    ns = modules new
 
-updateModule :: Ord i => ModInfo i t -> i -> t -> ModInfo i t
+updateModule :: ModInfo t -> Ident -> t -> ModInfo t
 updateModule (ModInfo mt ms fs me mw ops med js ps) i t = ModInfo mt ms fs me mw ops med (updateTree (i,t) js) ps
 
-replaceJudgements :: ModInfo i t -> BinTree i t -> ModInfo i t
+replaceJudgements :: ModInfo t -> Map.Map Ident t -> ModInfo t
 replaceJudgements (ModInfo mt ms fs me mw ops med _ ps) js = ModInfo mt ms fs me mw ops med js ps
 
-addOpenQualif :: i -> i -> ModInfo i t -> ModInfo i t
+addOpenQualif :: Ident -> Ident -> ModInfo t -> ModInfo t
 addOpenQualif i j (ModInfo mt ms fs me mw ops med js ps) = ModInfo mt ms fs me mw (OQualif i j : ops) med js ps
 
-addFlag :: Options -> ModInfo i t -> ModInfo i t
+addFlag :: Options -> ModInfo t -> ModInfo t
 addFlag f mo = mo {flags = flags mo `addOptions` f} 
 
-flagsModule :: (i,ModInfo i a) -> Options
+flagsModule :: (Ident,ModInfo a) -> Options
 flagsModule (_,mi) = flags mi
 
-allFlags :: MGrammar i a -> Options
+allFlags :: MGrammar a -> Options
 allFlags gr = concatOptions [flags m | (_,m) <- modules gr]
 
-mapModules :: (ModInfo i a -> ModInfo i a) -> MGrammar i a -> MGrammar i a 
+mapModules :: (ModInfo a -> ModInfo a) -> MGrammar a -> MGrammar a 
 mapModules f (MGrammar ms) = MGrammar (map (onSnd f) ms)
 
-data OpenSpec i = 
+data OpenSpec = 
-   OSimple i 
+   OSimple Ident
- | OQualif i i
+ | OQualif Ident Ident
-  deriving (Eq,Ord,Show)
+  deriving (Eq,Show)
 
 data ModuleStatus = 
    MSComplete 
  | MSIncomplete 
   deriving (Eq,Ord,Show)
 
-openedModule :: OpenSpec i -> i
+openedModule :: OpenSpec -> Ident
 openedModule o = case o of
   OSimple m -> m
   OQualif _ m -> m
 
 -- | initial dependency list
-depPathModule :: Ord i => ModInfo i a -> [OpenSpec i]
+depPathModule :: ModInfo a -> [OpenSpec]
 depPathModule m = fors m ++ exts m ++ opens m
   where
     fors m = 
@@ -152,7 +152,7 @@ depPathModule m = fors m ++ exts m ++ opens m
     exts m = map OSimple (extends m)
 
 -- | all dependencies
-allDepsModule :: Ord i => MGrammar i a -> ModInfo i a -> [OpenSpec i]
+allDepsModule :: MGrammar a -> ModInfo a -> [OpenSpec]
 allDepsModule gr m = iterFix add os0 where
   os0 = depPathModule m
   add os = [m | o <- os, Just n <- [lookup (openedModule o) mods], 
@@ -160,14 +160,14 @@ allDepsModule gr m = iterFix add os0 where
   mods = modules gr
 
 -- | select just those modules that a given one depends on, including itself
-partOfGrammar :: Ord i => MGrammar i a -> (i,ModInfo i a) -> MGrammar i a
+partOfGrammar :: MGrammar a -> (Ident,ModInfo a) -> MGrammar a
 partOfGrammar gr (i,m) = MGrammar [mo | mo@(j,_) <- mods, elem j modsFor] 
   where
     mods = modules gr
     modsFor = (i:) $ map openedModule $ allDepsModule gr m
 
 -- | all modules that a module extends, directly or indirectly, without restricts
-allExtends :: (Show i,Ord i) => MGrammar i a -> i -> [i]
+allExtends :: MGrammar a -> Ident -> [Ident]
 allExtends gr i =
   case lookupModule gr i of
     Ok m -> case extends m of 
@@ -176,7 +176,7 @@ allExtends gr i =
     _    -> []
 
 -- | all modules that a module extends, directly or indirectly, with restricts
-allExtendSpecs :: (Show i,Ord i) => MGrammar i a -> i -> [(i,MInclude i)]
+allExtendSpecs :: MGrammar a -> Ident -> [(Ident,MInclude)]
 allExtendSpecs gr i =
   case lookupModule gr i of
     Ok m -> case extend m of 
@@ -185,7 +185,7 @@ allExtendSpecs gr i =
     _    -> []
 
 -- | this plus that an instance extends its interface
-allExtendsPlus :: (Show i,Ord i) => MGrammar i a -> i -> [i]
+allExtendsPlus :: MGrammar a -> Ident -> [Ident]
 allExtendsPlus gr i =
   case lookupModule gr i of
     Ok m -> i : concatMap (allExtendsPlus gr) (exts m)
@@ -194,7 +194,7 @@ allExtendsPlus gr i =
     exts m = extends m ++ [j | MTInstance j <- [mtype m]]
 
 -- | conversely: all modules that extend a given module, incl. instances of interface
-allExtensions :: (Show i,Ord i) => MGrammar i a -> i -> [i]
+allExtensions :: MGrammar a -> Ident -> [Ident]
 allExtensions gr i =
   case lookupModule gr i of
     Ok m -> let es = exts i in es ++ concatMap (allExtensions gr) es
@@ -205,36 +205,29 @@ allExtensions gr i =
    mods = modules gr
 
 -- | initial search path: the nonqualified dependencies
-searchPathModule :: Ord i => ModInfo i a -> [i]
+searchPathModule :: ModInfo a -> [Ident]
 searchPathModule m = [i | OSimple i <- depPathModule m]
 
 -- | a new module can safely be added to the end, since nothing old can depend on it
-addModule :: Ord i => 
+addModule :: MGrammar a -> Ident -> ModInfo a -> MGrammar a
-             MGrammar i a -> i -> ModInfo i a -> MGrammar i a
 addModule gr name mi = MGrammar $ (modules gr ++ [(name,mi)])
 
-emptyMGrammar :: MGrammar i a
+emptyMGrammar :: MGrammar a
 emptyMGrammar = MGrammar []
 
-emptyModInfo :: ModInfo i a
+emptyModInfo :: ModInfo a
 emptyModInfo = ModInfo MTResource MSComplete noOptions [] Nothing [] [] emptyBinTree emptyBinTree
 
 -- | we store the module type with the identifier
-data IdentM i = IdentM {
-  identM :: i ,
-  typeM  :: ModuleType i
-  }
-  deriving (Eq,Ord,Show)
 
-abstractOfConcrete :: (Show i, Eq i) => MGrammar i a -> i -> Err i
+abstractOfConcrete :: MGrammar a -> Ident -> Err Ident
 abstractOfConcrete gr c = do
   n <- lookupModule gr c
   case mtype n of
     MTConcrete a -> return a
-    _ -> Bad $ "expected concrete" +++ show c
+    _ -> Bad $ render (text "expected concrete" <+> ppIdent c)
 
-abstractModOfConcrete :: (Show i, Eq i) => 
+abstractModOfConcrete :: MGrammar a -> Ident -> Err (ModInfo a)
-                         MGrammar i a -> i -> Err (ModInfo i a)
 abstractModOfConcrete gr c = do
   a <- abstractOfConcrete gr c
   lookupModule gr a
@@ -244,106 +237,110 @@ abstractModOfConcrete gr c = do
 
 --- canonFileName s = prt s ++ ".gfc"
 
-lookupModule :: (Show i,Eq i) => MGrammar i a -> i -> Err (ModInfo i a)
+lookupModule :: MGrammar a -> Ident -> Err (ModInfo a)
 lookupModule gr m = case lookup m (modules gr) of
-  Just i -> return i
+  Just i  -> return i
-  _ -> Bad $ "unknown module" +++ show m 
+  Nothing -> Bad $ render (text "unknown module" <+> ppIdent m <+> text "among" <+> hsep (map (ppIdent . fst) (modules gr)))
-             +++ "among" +++ unwords (map (show . fst) (modules gr)) ---- debug
 
-lookupModuleType :: (Show i,Eq i) => MGrammar i a -> i -> Err (ModuleType i)
+lookupModuleType :: MGrammar a -> Ident -> Err ModuleType
 lookupModuleType gr m = do
   mi <- lookupModule gr m
   return $ mtype mi
 
-lookupInfo :: (Show i, Ord i) => ModInfo i a -> i -> Err a
+lookupInfo :: ModInfo a -> Ident -> Err a
-lookupInfo mo i = lookupTree show i (jments mo)
+lookupInfo mo i = lookupTree showIdent i (jments mo)
 
-lookupPosition :: (Show i, Ord i) => ModInfo i a -> i -> Err (String,(Int,Int))
+lookupPosition :: ModInfo a -> Ident -> Err (String,(Int,Int))
-lookupPosition mo i = lookupTree show i (positions mo)
+lookupPosition mo i = lookupTree showIdent i (positions mo)
 
-ppPosition :: (Show i, Ord i) => ModInfo i a -> i -> Doc
+ppPosition :: ModInfo a -> Ident -> Doc
 ppPosition mo i = case lookupPosition mo i of
   Ok (f,(b,e)) | b == e    -> text "in" <+> text f <> text ", line" <+> int b
                | otherwise -> text "in" <+> text f <> text ", lines" <+> int b <> text "-" <> int e
   _ -> empty
 
-isModAbs :: ModInfo i a -> Bool
+isModAbs :: ModInfo a -> Bool
-isModAbs m = case mtype m of
+isModAbs m =
-  MTAbstract -> True
+  case mtype m of
-----  MTUnion t -> isModAbs t
+    MTAbstract -> True
-  _ -> False
+    _          -> False
 
-isModRes :: ModInfo i a -> Bool
+isModRes :: ModInfo a -> Bool
-isModRes m = case mtype m of
+isModRes m =
-  MTResource -> True
+  case mtype m of
-  MTInterface -> True ---
+    MTResource   -> True
-  MTInstance _ -> True
+    MTInterface  -> True ---
-  _ -> False
+    MTInstance _ -> True
+    _            -> False
 
-isModCnc :: ModInfo i a -> Bool
+isModCnc :: ModInfo a -> Bool
-isModCnc m = case mtype m of
+isModCnc m =
-  MTConcrete _ -> True
+  case mtype m of
-  _ -> False
+    MTConcrete _ -> True
+    _            -> False
 
-sameMType :: Eq i => ModuleType i -> ModuleType i -> Bool
+sameMType :: ModuleType -> ModuleType -> Bool
-sameMType m n = case (n,m) of
+sameMType m n =
-  (MTConcrete _, MTConcrete _) -> True
+  case (n,m) of
+    (MTConcrete _, MTConcrete _) -> True
 
-  (MTInstance _, MTInstance _) -> True
+    (MTInstance _, MTInstance _) -> True
-  (MTInstance _, MTResource)   -> True
+    (MTInstance _, MTResource)   -> True
-  (MTInstance _, MTConcrete _) -> True
+    (MTInstance _, MTConcrete _) -> True
 
-  (MTInterface,  MTInstance _) -> True
+    (MTInterface,  MTInstance _) -> True
-  (MTInterface,  MTResource)   -> True    -- for reuse
+    (MTInterface,  MTResource)   -> True    -- for reuse
-  (MTInterface,  MTAbstract)   -> True    -- for reuse
+    (MTInterface,  MTAbstract)   -> True    -- for reuse
-  (MTInterface,  MTConcrete _) -> True    -- for reuse
+    (MTInterface,  MTConcrete _) -> True    -- for reuse
 
-  (MTResource,   MTInstance _) -> True
+    (MTResource,   MTInstance _) -> True
-  (MTResource,   MTConcrete _) -> True    -- for reuse
+    (MTResource,   MTConcrete _) -> True    -- for reuse
 
-  _ -> m == n
+    _                            -> m == n
 
 -- | don't generate code for interfaces and for incomplete modules
-isCompilableModule :: ModInfo i a -> Bool
+isCompilableModule :: ModInfo a -> Bool
 isCompilableModule m =
   case mtype m of
     MTInterface -> False
     _           -> mstatus m == MSComplete
 
 -- | interface and "incomplete M" are not complete
-isCompleteModule :: (Eq i) =>  ModInfo i a -> Bool
+isCompleteModule :: ModInfo a -> Bool
 isCompleteModule m = mstatus m == MSComplete && mtype m /= MTInterface
 
 
 -- | all abstract modules sorted from least to most dependent
-allAbstracts :: (Ord i, Show i) => MGrammar i a -> [i]
+allAbstracts :: MGrammar a -> [Ident]
 allAbstracts gr = 
  case topoTest [(i,extends m) | (i,m) <- modules gr, mtype m == MTAbstract] of
-   Left is -> is
+   Left  is     -> is
-   Right cycles -> error $ "Cyclic abstract modules: " ++ show cycles
+   Right cycles -> error $ render (text "Cyclic abstract modules:" <+> vcat (map (hsep . map ppIdent) cycles))
 
 -- | the last abstract in dependency order (head of list)
-greatestAbstract :: (Ord i, Show i) => MGrammar i a -> Maybe i
+greatestAbstract :: MGrammar a -> Maybe Ident
-greatestAbstract gr = case allAbstracts gr of
+greatestAbstract gr =
-  [] -> Nothing
+  case allAbstracts gr of
-  as -> return $ last as
+    [] -> Nothing
+    as -> return $ last as
 
 -- | all resource modules
-allResources :: MGrammar i a -> [i]
+allResources :: MGrammar a -> [Ident]
 allResources gr = [i | (i,m) <- modules gr, isModRes m || isModCnc m]
 
 -- | the greatest resource in dependency order
-greatestResource :: MGrammar i a -> Maybe i
+greatestResource :: MGrammar a -> Maybe Ident
-greatestResource gr = case allResources gr of
+greatestResource gr =
-  [] -> Nothing
+  case allResources gr of
-  a -> return $ head a ---- why not last as in Abstract? works though AR 24/5/2008
+    [] -> Nothing
+    a  -> return $ head a ---- why not last as in Abstract? works though AR 24/5/2008
 
 -- | all concretes for a given abstract
-allConcretes :: Eq i => MGrammar i a -> i -> [i]
+allConcretes :: MGrammar a -> Ident -> [Ident]
-allConcretes gr a = 
+allConcretes gr a =
   [i | (i, m) <- modules gr, mtype m == MTConcrete a, isCompleteModule m]
 
 -- | all concrete modules for any abstract
-allConcreteModules :: Eq i => MGrammar i a -> [i]
+allConcreteModules :: MGrammar a -> [Ident]
-allConcreteModules gr = 
+allConcreteModules gr =
   [i | (i, m) <- modules gr, MTConcrete _ <- [mtype m], isCompleteModule m]