GF/src is now for 2.9, and the new sources are in src-3.0 - keep it this way until the release of GF 3

1 files changed, 814 insertions, 0 deletions

diff --git a/src-3.0/GF/Grammar/Macros.hs b/src-3.0/GF/Grammar/Macros.hs
new file mode 100644
index 000000000..7a48e7c3a
--- /dev/null
+++ b/src-3.0/GF/Grammar/Macros.hs
@@ -0,0 +1,814 @@
+----------------------------------------------------------------------
+-- |
+-- Module      : Macros
+-- Maintainer  : AR
+-- Stability   : (stable)
+-- Portability : (portable)
+--
+-- > CVS $Date: 2005/11/11 16:38:00 $ 
+-- > CVS $Author: bringert $
+-- > CVS $Revision: 1.24 $
+--
+-- Macros for constructing and analysing source code terms.
+--
+-- operations on terms and types not involving lookup in or reference to grammars
+--
+-- AR 7\/12\/1999 - 9\/5\/2000 -- 4\/6\/2001
+-----------------------------------------------------------------------------
+
+module GF.Grammar.Macros where
+
+import GF.Data.Operations
+import GF.Data.Str
+import GF.Grammar.Grammar
+import GF.Infra.Ident
+import GF.Grammar.PrGrammar
+
+import Control.Monad (liftM, liftM2)
+import Data.Char (isDigit)
+
+firstTypeForm :: Type -> Err (Context, Type)
+firstTypeForm t = case t of
+  Prod x a b  -> do
+    (x', val) <- firstTypeForm b 
+    return ((x,a):x',val)
+  _ -> return ([],t)
+
+qTypeForm :: Type -> Err (Context, Cat, [Term])
+qTypeForm t = case t of
+  Prod x a b  -> do
+    (x', cat, args) <- qTypeForm b 
+    return ((x,a):x', cat, args)
+  App c a -> do
+    (_,cat, args) <- qTypeForm c
+    return ([],cat,args ++ [a])
+  Q m c ->
+    return ([],(m,c),[]) 
+  QC m c ->
+    return ([],(m,c),[]) 
+  _       -> 
+    prtBad "no normal form of type" t
+
+qq :: QIdent -> Term
+qq (m,c) = Q m c
+
+typeForm :: Type -> Err (Context, Cat, [Term])
+typeForm = qTypeForm ---- no need to distinguish any more
+
+cPredef :: Ident
+cPredef = identC "Predef"
+
+cnPredef :: String -> Term
+cnPredef f = Q cPredef (identC f)
+
+typeFormCnc :: Type -> Err (Context, Type)
+typeFormCnc t = case t of
+  Prod x a b  -> do
+    (x', v) <- typeFormCnc b 
+    return ((x,a):x',v)
+  _ -> return ([],t)
+
+valCat :: Type -> Err Cat
+valCat typ = 
+  do (_,cat,_) <- typeForm typ
+     return cat
+
+valType :: Type -> Err Type
+valType typ = 
+  do (_,cat,xx) <- typeForm typ --- not optimal to do in this way
+     return $ mkApp (qq cat) xx
+
+valTypeCnc :: Type -> Err Type
+valTypeCnc typ = 
+  do (_,ty) <- typeFormCnc typ
+     return ty
+
+typeRawSkeleton :: Type -> Err ([(Int,Type)],Type)
+typeRawSkeleton typ =
+  do (cont,typ) <- typeFormCnc typ
+     args <- mapM (typeRawSkeleton . snd) cont
+     return ([(length c, v) | (c,v) <- args], typ)
+
+type MCat = (Ident,Ident)
+
+sortMCat :: String -> MCat
+sortMCat s = (zIdent "_", zIdent s)
+
+--- hack for Editing.actCat in empty state
+errorCat :: MCat
+errorCat = (zIdent "?", zIdent "?")
+
+getMCat :: Term -> Err MCat
+getMCat t = case t of
+  Q  m c -> return (m,c)
+  QC m c -> return (m,c)
+  Sort s -> return $ sortMCat s
+  App f _ -> getMCat f
+  _ -> prtBad "no qualified constant" t
+
+typeSkeleton :: Type -> Err ([(Int,MCat)],MCat)
+typeSkeleton typ = do
+  (cont,val) <- typeRawSkeleton typ
+  cont' <- mapPairsM getMCat cont
+  val'  <- getMCat val
+  return (cont',val')
+
+catSkeleton :: Type -> Err ([MCat],MCat)
+catSkeleton typ =
+  do (args,val) <- typeSkeleton typ
+     return (map snd args, val)
+
+funsToAndFrom :: Type -> (MCat, [(MCat,[Int])])
+funsToAndFrom t = errVal undefined $ do ---
+  (cs,v) <- catSkeleton t
+  let cis = zip cs [0..]
+  return $ (v, [(c,[i | (c',i) <- cis, c' == c]) | c <- cs])
+
+typeFormConcrete :: Type -> Err (Context, Type)
+typeFormConcrete t = case t of
+  Prod x a b  -> do 
+    (x', typ) <- typeFormConcrete b 
+    return ((x,a):x', typ)
+  _       -> return ([],t)
+
+isRecursiveType :: Type -> Bool
+isRecursiveType t = errVal False $ do
+  (cc,c) <- catSkeleton t -- thus recursivity on Cat level
+  return $ any (== c) cc
+
+isHigherOrderType :: Type -> Bool
+isHigherOrderType t = errVal True $ do  -- pessimistic choice
+  co <- contextOfType t
+  return $ not $ null [x | (x,Prod _ _ _) <- co]
+
+contextOfType :: Type -> Err Context
+contextOfType typ = case typ of
+  Prod x a b -> liftM ((x,a):) $ contextOfType b
+  _ -> return [] 
+
+unComputed :: Term -> Term
+unComputed t = case t of
+  Computed v -> unComputed v
+  _ -> t --- composSafeOp unComputed t
+
+
+{- 
+--- defined (better) in compile/PrOld
+
+stripTerm :: Term -> Term
+stripTerm t = case t of
+  Q _ c  -> Cn c
+  QC _ c -> Cn c
+  T ti psts -> T ti [(stripPatt p, stripTerm v) | (p,v) <- psts]
+  _ -> composSafeOp stripTerm t
+ where
+   stripPatt p = errVal p $ term2patt $ stripTerm $ patt2term p
+-}
+
+computed :: Term -> Term
+computed = Computed
+
+termForm :: Term -> Err ([(Ident)], Term, [Term])
+termForm t = case t of
+   Abs x b  ->
+     do (x', fun, args) <- termForm b 
+        return (x:x', fun, args)
+   App c a ->
+     do (_,fun, args) <- termForm c
+        return ([],fun,args ++ [a]) 
+   _       -> 
+     return ([],t,[])
+
+termFormCnc :: Term -> ([(Ident)], Term)
+termFormCnc t = case t of
+   Abs x b  -> (x:xs, t') where (xs,t') = termFormCnc b 
+   _        -> ([],t)
+
+appForm :: Term -> (Term, [Term])
+appForm t = case t of
+  App c a -> (fun, args ++ [a]) where (fun, args) = appForm c
+  _       -> (t,[])
+
+varsOfType :: Type -> [Ident]
+varsOfType t = case t of
+  Prod x _ b -> x : varsOfType b
+  _ -> []
+
+mkProdSimple :: Context -> Term -> Term
+mkProdSimple c t = mkProd (c,t,[])
+
+mkProd :: (Context, Term, [Term]) -> Term
+mkProd ([],typ,args) = mkApp typ args
+mkProd ((x,a):dd, typ, args) = Prod x a (mkProd (dd, typ, args))
+
+mkTerm :: ([(Ident)], Term, [Term]) -> Term
+mkTerm (xx,t,aa) = mkAbs xx (mkApp t aa)
+
+mkApp :: Term -> [Term] -> Term
+mkApp = foldl App
+
+mkAbs :: [Ident] -> Term -> Term
+mkAbs xx t = foldr Abs t xx
+
+appCons :: Ident -> [Term] -> Term
+appCons = mkApp . Cn
+
+appc :: String -> [Term] -> Term
+appc = appCons . zIdent
+
+appqc :: String -> String -> [Term] -> Term
+appqc q c = mkApp (Q (zIdent q) (zIdent c))
+
+mkLet :: [LocalDef] -> Term -> Term
+mkLet defs t = foldr Let t defs
+
+mkLetUntyped :: Context -> Term -> Term
+mkLetUntyped defs = mkLet [(x,(Nothing,t)) | (x,t) <- defs]
+
+isVariable :: Term -> Bool
+isVariable (Vr _ ) = True
+isVariable _ = False
+
+eqIdent :: Ident -> Ident -> Bool
+eqIdent = (==)
+
+zIdent :: String -> Ident
+zIdent s = identC s
+
+uType :: Type
+uType = Cn (zIdent "UndefinedType")
+
+assign :: Label -> Term -> Assign
+assign l t = (l,(Nothing,t))
+
+assignT :: Label -> Type -> Term -> Assign
+assignT l a t = (l,(Just a,t))
+
+unzipR :: [Assign] -> ([Label],[Term])
+unzipR r = (ls, map snd ts) where (ls,ts) = unzip r
+
+mkAssign :: [(Label,Term)] -> [Assign]
+mkAssign lts = [assign l t | (l,t) <- lts]
+
+zipAssign :: [Label] -> [Term] -> [Assign]
+zipAssign ls ts = [assign l t | (l,t) <- zip ls ts]
+
+ident2label :: Ident -> Label
+ident2label c = LIdent (prIdent c)
+
+label2ident :: Label -> Ident
+label2ident = identC . prLabel
+
+prLabel :: Label -> String
+prLabel = prt
+
+mapAssignM :: Monad m => (Term -> m c) -> [Assign] -> m [(Label,(Maybe c,c))]
+mapAssignM f = mapM (\ (ls,tv) -> liftM ((,) ls) (g tv))
+  where g (t,v) = liftM2 (,) (maybe (return Nothing) (liftM Just . f) t) (f v)
+
+mkRecordN :: Int -> (Int -> Label) -> [Term] -> Term
+mkRecordN int lab typs = R [ assign (lab i) t | (i,t) <- zip [int..] typs]
+
+mkRecord :: (Int -> Label) -> [Term] -> Term
+mkRecord = mkRecordN 0
+
+mkRecTypeN :: Int -> (Int -> Label) -> [Type] -> Type
+mkRecTypeN int lab typs = RecType [ (lab i, t) | (i,t) <- zip [int..] typs]
+
+mkRecType :: (Int -> Label) -> [Type] -> Type
+mkRecType = mkRecTypeN 0
+
+record2subst :: Term -> Err Substitution
+record2subst t = case t of
+  R fs -> return [(zIdent x, t) | (LIdent x,(_,t)) <- fs]
+  _ -> prtBad "record expected, found" t
+
+typeType, typePType, typeStr, typeTok, typeStrs :: Term
+
+typeType  = srt "Type"
+typePType = srt "PType"
+typeStr   = srt "Str"
+typeTok   = srt "Tok"
+typeStrs  = srt "Strs"
+
+typeString, typeFloat, typeInt :: Term
+typeInts :: Integer -> Term
+
+typeString = constPredefRes "String"
+typeInt = constPredefRes "Int"
+typeFloat = constPredefRes "Float"
+typeInts i = App (constPredefRes "Ints") (EInt i)
+
+isTypeInts :: Term -> Bool
+isTypeInts ty = case ty of
+  App c _ -> c == constPredefRes "Ints"
+  _ -> False
+
+constPredefRes :: String -> Term
+constPredefRes s = Q (IC "Predef") (zIdent s)
+
+isPredefConstant :: Term -> Bool
+isPredefConstant t = case t of
+  Q (IC "Predef") _ -> True
+  Q (IC "PredefAbs") _ -> True
+  _ -> False
+
+isPredefAbsType :: Ident -> Bool
+isPredefAbsType c = elem c [zIdent "Int", zIdent "String"]
+
+mkSelects :: Term -> [Term] -> Term
+mkSelects t tt = foldl S t tt
+
+mkTable :: [Term] -> Term -> Term
+mkTable tt t = foldr Table t tt
+
+mkCTable :: [Ident] -> Term -> Term
+mkCTable ids v = foldr ccase v ids where 
+  ccase x t = T TRaw [(PV x,t)]
+
+mkDecl :: Term -> Decl
+mkDecl typ = (wildIdent, typ)
+
+eqStrIdent :: Ident -> Ident -> Bool
+eqStrIdent = (==)
+
+tupleLabel, linLabel :: Int -> Label
+tupleLabel i = LIdent $ "p" ++ show i
+linLabel i = LIdent $ "s" ++ show i
+
+theLinLabel :: Label
+theLinLabel = LIdent "s"
+
+tuple2record :: [Term] -> [Assign]
+tuple2record ts = [assign (tupleLabel i) t | (i,t) <- zip [1..] ts]
+
+tuple2recordType :: [Term] -> [Labelling]
+tuple2recordType ts = [(tupleLabel i, t) | (i,t) <- zip [1..] ts]
+
+tuple2recordPatt :: [Patt] -> [(Label,Patt)]
+tuple2recordPatt ts = [(tupleLabel i, t) | (i,t) <- zip [1..] ts]
+
+mkCases :: Ident -> Term -> Term
+mkCases x t = T TRaw [(PV x, t)]
+
+mkWildCases :: Term -> Term
+mkWildCases = mkCases wildIdent
+
+mkFunType :: [Type] -> Type -> Type
+mkFunType tt t = mkProd ([(wildIdent, ty) | ty <- tt], t, []) -- nondep prod
+
+plusRecType :: Type -> Type -> Err Type
+plusRecType t1 t2 = case (unComputed t1, unComputed t2) of
+  (RecType r1, RecType r2) -> case
+    filter (`elem` (map fst r1)) (map fst r2) of
+      [] -> return (RecType (r1 ++ r2))
+      ls -> Bad $ "clashing labels" +++ unwords (map prt ls)
+  _ -> Bad ("cannot add record types" +++ prt t1 +++ "and" +++ prt t2) 
+
+plusRecord :: Term -> Term -> Err Term
+plusRecord t1 t2 =
+ case (t1,t2) of
+   (R r1, R r2 ) -> return (R ([(l,v) | -- overshadowing of old fields
+                              (l,v) <- r1, not (elem l (map fst r2)) ] ++ r2))
+   (_,    FV rs) -> mapM (plusRecord t1) rs >>= return . FV
+   (FV rs,_    ) -> mapM (`plusRecord` t2) rs >>= return . FV
+   _ -> Bad ("cannot add records" +++ prt t1 +++ "and" +++ prt t2)
+
+-- | default linearization type
+defLinType :: Type
+defLinType = RecType [(LIdent "s",  typeStr)]
+
+-- | refreshing variables
+varX :: Int -> Ident
+varX i = identV (i,"x")
+
+-- | refreshing variables
+mkFreshVar :: [Ident] -> Ident
+mkFreshVar olds = varX (maxVarIndex olds + 1) 
+
+-- | trying to preserve a given symbol
+mkFreshVarX :: [Ident] -> Ident -> Ident
+mkFreshVarX olds x = if (elem x olds) then (varX (maxVarIndex olds + 1)) else x
+
+maxVarIndex :: [Ident] -> Int
+maxVarIndex = maximum . ((-1):) . map varIndex
+
+mkFreshVars :: Int -> [Ident] -> [Ident] 
+mkFreshVars n olds = [varX (maxVarIndex olds + i) | i <- [1..n]]
+
+-- | quick hack for refining with var in editor
+freshAsTerm :: String -> Term
+freshAsTerm s = Vr (varX (readIntArg s))
+
+-- | create a terminal for concrete syntax
+string2term :: String -> Term
+string2term = K
+
+int2term :: Integer -> Term
+int2term = EInt
+
+float2term :: Double -> Term
+float2term = EFloat
+
+-- | create a terminal from identifier
+ident2terminal :: Ident -> Term
+ident2terminal = K . prIdent
+
+-- | create a constant
+string2CnTrm :: String -> Term
+string2CnTrm = Cn . zIdent
+
+symbolOfIdent :: Ident -> String
+symbolOfIdent = prIdent
+
+symid :: Ident -> String
+symid = symbolOfIdent
+
+vr :: Ident -> Term
+cn :: Ident -> Term
+srt :: String -> Term
+meta :: MetaSymb -> Term
+cnIC :: String -> Term
+
+vr = Vr
+cn = Cn
+srt = Sort
+meta = Meta
+cnIC = cn . IC
+
+justIdentOf :: Term -> Maybe Ident
+justIdentOf (Vr x) = Just x
+justIdentOf (Cn x) = Just x
+justIdentOf _ = Nothing
+
+isMeta :: Term -> Bool
+isMeta (Meta _) = True
+isMeta _ = False
+
+mkMeta :: Int -> Term
+mkMeta = Meta . MetaSymb
+
+nextMeta :: MetaSymb -> MetaSymb
+nextMeta = int2meta . succ . metaSymbInt
+
+int2meta :: Int -> MetaSymb
+int2meta = MetaSymb
+
+metaSymbInt :: MetaSymb -> Int
+metaSymbInt (MetaSymb k) = k
+
+freshMeta :: [MetaSymb] -> MetaSymb
+freshMeta ms = MetaSymb (minimum [n | n <- [0..length ms], 
+                                      notElem n (map metaSymbInt ms)])
+
+mkFreshMetasInTrm :: [MetaSymb] -> Trm -> Trm
+mkFreshMetasInTrm metas = fst . rms minMeta where
+  rms meta trm = case trm of
+    Meta m  -> (Meta (MetaSymb meta), meta + 1)
+    App f a -> let (f',msf) = rms meta f 
+                   (a',msa) = rms msf a
+               in (App f' a', msa)
+    Prod x a b -> 
+               let (a',msa) = rms meta a 
+                   (b',msb) = rms msa b
+               in (Prod x a' b', msb)
+    Abs x b -> let (b',msb) = rms meta b in (Abs x b', msb)
+    _       -> (trm,meta)
+  minMeta = if null metas then 0 else (maximum (map metaSymbInt metas) + 1)
+
+-- | decides that a term has no metavariables
+isCompleteTerm :: Term -> Bool
+isCompleteTerm t = case t of
+  Meta _  -> False
+  Abs _ b -> isCompleteTerm b
+  App f a -> isCompleteTerm f && isCompleteTerm a
+  _       -> True 
+
+linTypeStr :: Type
+linTypeStr = mkRecType linLabel [typeStr] -- default lintype {s :: Str}
+
+linAsStr :: String -> Term
+linAsStr s = mkRecord linLabel [K s] -- default linearization {s = s}
+
+linDefStr :: Term
+linDefStr = Abs s (R [assign (linLabel 0) (Vr s)]) where s = zIdent "s"
+
+term2patt :: Term -> Err Patt
+term2patt trm = case termForm trm of
+  Ok ([], Vr x, []) -> return (PV x)
+  Ok ([], Val ty x, []) -> return (PVal ty x)
+  Ok ([], Con c, aa) -> do
+    aa' <- mapM term2patt aa
+    return (PC c aa')
+  Ok ([], QC p c, aa) -> do
+    aa' <- mapM term2patt aa
+    return (PP p c aa')
+
+  Ok ([], Q p c, []) -> do
+    return (PM p c)
+
+  Ok ([], R r, []) -> do
+    let (ll,aa) = unzipR r
+    aa' <- mapM term2patt aa
+    return (PR (zip ll aa'))
+  Ok ([],EInt i,[]) -> return $ PInt i
+  Ok ([],EFloat i,[]) -> return $ PFloat i
+  Ok ([],K s,   []) -> return $ PString s
+
+--- encodings due to excessive use of term-patt convs. AR 7/1/2005
+  Ok ([], Cn (IC "@"), [Vr a,b]) -> do
+    b' <- term2patt b
+    return (PAs a b')
+  Ok ([], Cn (IC "-"), [a]) -> do
+    a' <- term2patt a
+    return (PNeg a')
+  Ok ([], Cn (IC "*"), [a]) -> do
+    a' <- term2patt a
+    return (PRep a')
+  Ok ([], Cn (IC "?"), []) -> do
+    return PChar
+  Ok ([], Cn (IC "[]"),[K s]) -> do
+    return $ PChars s
+  Ok ([], Cn (IC "+"), [a,b]) -> do
+    a' <- term2patt a
+    b' <- term2patt b
+    return (PSeq a' b')
+  Ok ([], Cn (IC "|"), [a,b]) -> do
+    a' <- term2patt a
+    b' <- term2patt b
+    return (PAlt a' b')
+
+  Ok ([], Cn c, []) -> do
+    return (PMacro c)
+
+  _ -> prtBad "no pattern corresponds to term" trm
+
+patt2term :: Patt -> Term
+patt2term pt = case pt of
+  PV x      -> Vr x
+  PW        -> Vr wildIdent             --- not parsable, should not occur
+  PVal t i  -> Val t i
+  PMacro c  -> Cn c
+  PM p c    -> Q p c
+
+  PC c pp   -> mkApp (Con c) (map patt2term pp)
+  PP p c pp -> mkApp (QC p c) (map patt2term pp)
+
+  PR r      -> R [assign l (patt2term p) | (l,p) <- r] 
+  PT _ p    -> patt2term p
+  PInt i    -> EInt i
+  PFloat i  -> EFloat i
+  PString s -> K s 
+
+  PAs x p   -> appc "@" [Vr x, patt2term p]            --- an encoding
+  PChar     -> appc "?" []                             --- an encoding
+  PChars s  -> appc "[]" [K s]                         --- an encoding
+  PSeq a b  -> appc "+" [(patt2term a), (patt2term b)] --- an encoding
+  PAlt a b  -> appc "|" [(patt2term a), (patt2term b)] --- an encoding
+  PRep a    -> appc "*" [(patt2term a)]                --- an encoding
+  PNeg a    -> appc "-" [(patt2term a)]                --- an encoding
+
+
+redirectTerm :: Ident -> Term -> Term
+redirectTerm n t = case t of
+  QC _ f -> QC n f
+  Q _ f  -> Q  n f
+  _ -> composSafeOp (redirectTerm n) t
+
+-- | to gather s-fields; assumes term in normal form, preserves label
+allLinFields :: Term -> Err [[(Label,Term)]]
+allLinFields trm = case unComputed trm of
+----  R rs  -> return [[(l,t) | (l,(Just ty,t)) <- rs, isStrType ty]] -- good
+  R rs  -> return [[(l,t) | (l,(_,t)) <- rs, isLinLabel l]] ---- bad
+  FV ts -> do
+    lts <- mapM allLinFields ts
+    return $ concat lts
+  _ -> prtBad "fields can only be sought in a record not in" trm
+
+-- | deprecated
+isLinLabel :: Label -> Bool
+isLinLabel l = case l of
+     LIdent ('s':cs) | all isDigit cs -> True
+     _ -> False
+
+-- | to gather ultimate cases in a table; preserves pattern list
+allCaseValues :: Term -> [([Patt],Term)]
+allCaseValues trm = case unComputed trm of
+  T _ cs -> [(p:ps, t) | (p,t0) <- cs, (ps,t) <- allCaseValues t0]
+  _      -> [([],trm)]
+
+-- | to gather all linearizations; assumes normal form, preserves label and args
+allLinValues :: Term -> Err [[(Label,[([Patt],Term)])]]
+allLinValues trm = do
+  lts <- allLinFields trm
+  mapM (mapPairsM (return . allCaseValues)) lts
+
+-- | to mark str parts of fields in a record f by a function f
+markLinFields :: (Term -> Term) -> Term -> Term
+markLinFields f t = case t of
+    R r -> R $ map mkField r
+    _ -> t
+ where
+  mkField (l,(_,t)) = if (isLinLabel l) then (assign l (mkTbl t)) else (assign l t)
+  mkTbl t = case t of
+    T i cs -> T i [(p, mkTbl v) | (p,v) <- cs]
+    _ -> f t
+
+-- | to get a string from a term that represents a sequence of terminals
+strsFromTerm :: Term -> Err [Str]
+strsFromTerm t = case unComputed t of
+  K s   -> return [str s]
+  Empty -> return [str []]
+  C s t -> do
+    s' <- strsFromTerm s
+    t' <- strsFromTerm t
+    return [plusStr x y | x <- s', y <- t']
+  Glue s t -> do
+    s' <- strsFromTerm s
+    t' <- strsFromTerm t
+    return [glueStr x y | x <- s', y <- t']
+  Alts (d,vs) -> do
+    d0 <- strsFromTerm d
+    v0 <- mapM (strsFromTerm . fst) vs
+    c0 <- mapM (strsFromTerm . snd) vs
+    let vs' = zip v0 c0
+    return [strTok (str2strings def) vars | 
+              def  <- d0,
+              vars <- [[(str2strings v, map sstr c) | (v,c) <- zip vv c0] | 
+                                                          vv <- combinations v0]
+           ]
+  FV ts -> mapM strsFromTerm ts >>= return . concat
+  Strs ts -> mapM strsFromTerm ts >>= return . concat  
+  Ready ss -> return [ss]
+  Alias _ _ d -> strsFromTerm d --- should not be needed...
+  _ -> prtBad "cannot get Str from term" t
+
+-- | to print an Str-denoting term as a string; if the term is of wrong type, the error msg
+stringFromTerm :: Term -> String
+stringFromTerm = err id (ifNull "" (sstr . head)) . strsFromTerm
+
+
+-- | to define compositional term functions
+composSafeOp :: (Term -> Term) -> Term -> Term
+composSafeOp op trm = case composOp (mkMonadic op) trm of
+  Ok t -> t
+  _ -> error "the operation is safe isn't it ?"
+ where
+ mkMonadic f = return . f
+
+-- | to define compositional term functions
+composOp :: Monad m => (Term -> m Term) -> Term -> m Term
+composOp co trm = 
+ case trm of
+   App c a -> 
+     do c' <- co c
+        a' <- co a
+        return (App c' a')
+   Abs x b ->
+     do b' <- co b
+        return (Abs x b')
+   Prod x a b -> 
+     do a' <- co a
+        b' <- co b
+        return (Prod x a' b')
+   S c a -> 
+     do c' <- co c
+        a' <- co a
+        return (S c' a')
+   Table a c -> 
+     do a' <- co a
+        c' <- co c
+        return (Table a' c')
+   R r -> 
+     do r' <- mapAssignM co r
+        return (R r')
+   RecType r -> 
+     do r' <- mapPairListM (co . snd) r
+        return (RecType r')
+   P t i ->
+     do t' <- co t
+        return (P t' i)
+   PI t i j ->
+     do t' <- co t
+        return (PI t' i j)
+   ExtR a c -> 
+     do a' <- co a
+        c' <- co c
+        return (ExtR a' c')
+
+   T i cc -> 
+     do cc' <- mapPairListM (co . snd) cc
+        i'  <- changeTableType co i
+        return (T i' cc')
+
+   TSh i cc -> 
+     do cc' <- mapPairListM (co . snd) cc
+        i'  <- changeTableType co i
+        return (TSh i' cc')
+
+   Eqs cc -> 
+     do cc' <- mapPairListM (co . snd) cc
+        return (Eqs cc')
+
+   V ty vs ->
+     do ty' <- co ty
+        vs' <- mapM co vs
+        return (V ty' vs')
+
+   Val ty i ->
+     do ty' <- co ty
+        return (Val ty' i)
+
+   Let (x,(mt,a)) b -> 
+     do a'  <- co a
+        mt' <- case mt of
+                 Just t -> co t >>= (return . Just) 
+                 _ -> return mt
+        b'  <- co b
+        return (Let (x,(mt',a')) b')
+   Alias c ty d -> 
+     do v <- co d
+        ty' <- co ty
+        return $ Alias c ty' v
+   C s1 s2 -> 
+     do v1 <- co s1 
+        v2 <- co s2
+        return (C v1 v2)
+   Glue s1 s2 -> 
+     do v1 <- co s1
+        v2 <- co s2
+        return (Glue v1 v2)
+   Alts (t,aa) ->
+     do t' <- co t
+        aa' <- mapM (pairM co) aa
+        return (Alts (t',aa'))
+   FV ts -> mapM co ts >>= return . FV
+   Strs tt -> mapM co tt >>= return . Strs
+
+   EPattType ty -> 
+     do ty' <- co ty
+        return (EPattType ty')
+
+   _ -> return trm -- covers K, Vr, Cn, Sort, EPatt
+
+getTableType :: TInfo -> Err Type
+getTableType i = case i of
+  TTyped ty -> return ty
+  TComp ty  -> return ty
+  TWild ty  -> return ty
+  _ -> Bad "the table is untyped"
+
+changeTableType :: Monad m => (Type -> m Type) -> TInfo -> m TInfo
+changeTableType co i = case i of
+    TTyped ty -> co ty >>= return . TTyped
+    TComp ty  -> co ty >>= return . TComp
+    TWild ty  -> co ty >>= return . TWild
+    _ -> return i
+
+collectOp :: (Term -> [a]) -> Term -> [a]
+collectOp co trm = case trm of
+  App c a    -> co c ++ co a 
+  Abs _ b    -> co b
+  Prod _ a b -> co a ++ co b 
+  S c a      -> co c ++ co a
+  Table a c  -> co a ++ co c
+  ExtR a c   -> co a ++ co c
+  R r        -> concatMap (\ (_,(mt,a)) -> maybe [] co mt ++ co a) r 
+  RecType r  -> concatMap (co . snd) r 
+  P t i      -> co t
+  T _ cc     -> concatMap (co . snd) cc -- not from patterns --- nor from type annot
+  TSh _ cc   -> concatMap (co . snd) cc -- not from patterns --- nor from type annot
+  V _ cc     -> concatMap co         cc --- nor from type annot
+  Let (x,(mt,a)) b -> maybe [] co mt ++ co a ++ co b
+  C s1 s2    -> co s1 ++ co s2 
+  Glue s1 s2 -> co s1 ++ co s2 
+  Alts (t,aa) -> let (x,y) = unzip aa in co t ++ concatMap co (x ++ y)
+  FV ts      -> concatMap co ts
+  Strs tt    -> concatMap co tt
+  _ -> [] -- covers K, Vr, Cn, Sort, Ready
+
+-- | to find the word items in a term
+wordsInTerm :: Term -> [String]
+wordsInTerm trm = filter (not . null) $ case trm of
+   K s     -> [s]
+   S c _   -> wo c
+   Alts (t,aa) -> wo t ++ concatMap (wo . fst) aa
+   Ready s -> allItems s
+   _       -> collectOp wo trm
+ where wo = wordsInTerm
+
+noExist :: Term
+noExist = FV []
+
+defaultLinType :: Type
+defaultLinType = mkRecType linLabel [typeStr]
+
+metaTerms :: [Term]
+metaTerms = map (Meta . MetaSymb) [0..]
+
+-- | from GF1, 20\/9\/2003
+isInOneType :: Type -> Bool
+isInOneType t = case t of
+  Prod _ a b -> a == b
+  _ -> False
+