reorganize the directories under src, and rescue the JavaScript interpreter from deprecated

3 files changed, 515 insertions, 0 deletions

diff --git a/src/compiler/GF/Compile/Abstract/Compute.hs b/src/compiler/GF/Compile/Abstract/Compute.hs
new file mode 100644
index 000000000..d5c9a163c
--- /dev/null
+++ b/src/compiler/GF/Compile/Abstract/Compute.hs
@@ -0,0 +1,138 @@
+----------------------------------------------------------------------
+-- |
+-- Module      : GF.Compile.Abstract.Compute
+-- Maintainer  : AR
+-- Stability   : (stable)
+-- Portability : (portable)
+--
+-- > CVS $Date: 2005/10/02 20:50:19 $ 
+-- > CVS $Author: aarne $
+-- > CVS $Revision: 1.8 $
+--
+-- computation in abstract syntax w.r.t. explicit definitions.
+--
+-- old GF computation; to be updated
+-----------------------------------------------------------------------------
+
+module GF.Compile.Abstract.Compute (LookDef,
+		   compute, 
+		   computeAbsTerm, 
+		   computeAbsTermIn, 
+		   beta
+		  ) where
+
+import GF.Data.Operations
+
+import GF.Grammar
+import GF.Grammar.Lookup
+
+import Debug.Trace
+import Data.List(intersperse)
+import Control.Monad (liftM, liftM2)
+import Text.PrettyPrint
+
+-- for debugging
+tracd m t = t 
+-- tracd = trace
+
+compute :: SourceGrammar -> Exp -> Err Exp
+compute = computeAbsTerm
+
+computeAbsTerm :: SourceGrammar -> Exp -> Err Exp
+computeAbsTerm gr = computeAbsTermIn (lookupAbsDef gr) []
+
+-- | a hack to make compute work on source grammar as well
+type LookDef = Ident -> Ident -> Err (Maybe Int,Maybe [Equation])
+
+computeAbsTermIn :: LookDef -> [Ident] -> Exp -> Err Exp
+computeAbsTermIn lookd xs e = errIn (render (text "computing" <+> ppTerm Unqualified 0 e)) $ compt xs e where
+  compt vv t = case t of
+--    Prod x a b  -> liftM2 (Prod x) (compt vv a) (compt (x:vv) b)
+--    Abs x b     -> liftM  (Abs  x)              (compt (x:vv) b)
+    _ -> do
+      let t' = beta vv t
+      (yy,f,aa) <- termForm t'
+      let vv' = map snd yy ++ vv
+      aa'    <- mapM (compt vv') aa
+      case look f of
+        Just eqs -> tracd (text "\nmatching" <+> ppTerm Unqualified 0 f) $ 
+                          case findMatch eqs aa' of
+          Ok (d,g) -> do
+            --- let (xs,ts) = unzip g
+            --- ts' <- alphaFreshAll vv' ts
+            let g' = g --- zip xs ts'
+            d' <- compt vv' $ substTerm vv' g' d
+            tracd (text "by Egs:" <+> ppTerm Unqualified 0 d') $ return $ mkAbs yy $ d'
+          _ -> tracd (text "no match" <+> ppTerm Unqualified 0 t') $ 
+               do
+            let v = mkApp f aa'
+            return $ mkAbs yy $ v
+        _ -> do
+          let t2 = mkAbs yy $ mkApp f aa'
+          tracd (text "not defined" <+> ppTerm Unqualified 0 t2) $ return t2
+
+  look t = case t of
+     (Q m f) -> case lookd m f of
+       Ok (_,md) -> md
+       _ -> Nothing
+     _ -> Nothing
+
+beta :: [Ident] -> Exp -> Exp
+beta vv c = case c of
+  Let (x,(_,a)) b -> beta vv $ substTerm vv [(x,beta vv a)] (beta (x:vv) b) 
+  App f         a -> 
+    let (a',f') = (beta vv a, beta vv f) in 
+    case f' of
+      Abs _ x b -> beta vv $ substTerm vv [(x,a')] (beta (x:vv) b) 
+      _ ->               (if a'==a && f'==f then id else beta vv) $ App f' a'
+  Prod b x a t      -> Prod b x (beta vv a) (beta (x:vv) t)
+  Abs b x t       -> Abs b x (beta (x:vv) t)
+  _               -> c
+
+-- special version of pattern matching, to deal with comp under lambda
+
+findMatch :: [([Patt],Term)] -> [Term] -> Err (Term, Substitution)
+findMatch cases terms = case cases of
+  [] -> Bad $ render (text "no applicable case for" <+> hcat (punctuate comma (map (ppTerm Unqualified 0) terms)))
+  (patts,_):_ | length patts /= length terms -> 
+       Bad (render (text "wrong number of args for patterns :" <+> 
+                    hsep (map (ppPatt Unqualified 0) patts) <+> text "cannot take" <+> hsep (map (ppTerm Unqualified 0) terms)))
+  (patts,val):cc -> case mapM tryMatch (zip patts terms) of
+     Ok substs -> return (tracd (text "value" <+> ppTerm Unqualified 0 val) val, concat substs)
+     _         -> findMatch cc terms
+
+tryMatch :: (Patt, Term) -> Err [(Ident, Term)]
+tryMatch (p,t) = do 
+  t' <- termForm t
+  trym p t'
+ where
+
+  trym p t' = err (\s -> tracd s (Bad s)) (\t -> tracd (prtm p t) (return t)) $ ---- 
+              case (p,t') of
+    (PW,    _) | notMeta t -> return [] -- optimization with wildcard
+    (PV x,  _) | notMeta t -> return [(x,t)]
+    (PString s, ([],K i,[])) | s==i -> return []
+    (PInt s, ([],EInt i,[])) | s==i -> return []
+    (PFloat s,([],EFloat i,[])) | s==i -> return [] --- rounding?
+    (PP q p pp, ([], QC r f, tt)) | 
+       p `eqStrIdent` f && length pp == length tt -> do
+         matches <- mapM tryMatch (zip pp tt)
+         return (concat matches)
+    (PP q p pp, ([], Q r f, tt)) | 
+       p `eqStrIdent` f && length pp == length tt -> do
+         matches <- mapM tryMatch (zip pp tt)
+         return (concat matches)
+    (PT _ p',_) -> trym p' t'
+    (PAs x p',_) -> do
+       subst <- trym p' t'
+       return $ (x,t) : subst
+    _ -> Bad (render (text "no match in pattern" <+> ppPatt Unqualified 0 p <+> text "for" <+> ppTerm Unqualified 0 t))
+
+  notMeta e = case e of
+    Meta _  -> False
+    App f a -> notMeta f &&  notMeta a  
+    Abs _ _ b -> notMeta b
+    _ -> True
+
+  prtm p g = 
+    ppPatt Unqualified 0 p <+> colon $$ hsep (punctuate semi [ppIdent x <+> char '=' <+> ppTerm Unqualified 0 y | (x,y) <- g])
diff --git a/src/compiler/GF/Compile/Abstract/TC.hs b/src/compiler/GF/Compile/Abstract/TC.hs
new file mode 100644
index 000000000..163301838
--- /dev/null
+++ b/src/compiler/GF/Compile/Abstract/TC.hs
@@ -0,0 +1,294 @@
+----------------------------------------------------------------------
+-- |
+-- Module      : TC
+-- Maintainer  : AR
+-- Stability   : (stable)
+-- Portability : (portable)
+--
+-- > CVS $Date: 2005/10/02 20:50:19 $ 
+-- > CVS $Author: aarne $
+-- > CVS $Revision: 1.11 $
+--
+-- Thierry Coquand's type checking algorithm that creates a trace
+-----------------------------------------------------------------------------
+
+module GF.Compile.Abstract.TC (AExp(..),
+	   Theory,
+	   checkExp,
+	   inferExp,
+	   checkBranch,
+	   eqVal,
+	   whnf
+	  ) where
+
+import GF.Data.Operations
+import GF.Grammar
+import GF.Grammar.Predef
+
+import Control.Monad
+import Data.List (sortBy)
+import Data.Maybe
+import Text.PrettyPrint
+
+data AExp =
+     AVr   Ident Val 
+   | ACn   QIdent Val
+   | AType 
+   | AInt  Integer 
+   | AFloat Double
+   | AStr  String
+   | AMeta MetaId Val
+   | AApp  AExp AExp Val 
+   | AAbs  Ident Val AExp 
+   | AProd Ident AExp AExp 
+   | AEqs  [([Exp],AExp)] --- not used
+   | ARecType [ALabelling]
+   | AR    [AAssign]
+   | AP    AExp Label Val
+   | AData Val
+  deriving (Eq,Show)
+
+type ALabelling = (Label, AExp) 
+type AAssign = (Label, (Val, AExp))
+
+type Theory = QIdent -> Err Val
+
+lookupConst :: Theory -> QIdent -> Err Val
+lookupConst th f = th f
+
+lookupVar :: Env -> Ident -> Err Val
+lookupVar g x = maybe (Bad (render (text "unknown variable" <+> ppIdent x))) return $ lookup x ((IW,uVal):g)
+-- wild card IW: no error produced, ?0 instead.
+
+type TCEnv = (Int,Env,Env)
+
+emptyTCEnv :: TCEnv
+emptyTCEnv = (0,[],[])
+
+whnf :: Val -> Err Val
+whnf v = ---- errIn ("whnf" +++ prt v) $ ---- debug
+         case v of
+  VApp u w -> do
+    u' <- whnf u 
+    w' <- whnf w
+    app u' w'
+  VClos env e -> eval env e
+  _ -> return v
+
+app :: Val -> Val -> Err Val
+app u v = case u of
+  VClos env (Abs _ x e) -> eval ((x,v):env) e
+  _ -> return $ VApp u v
+  
+eval :: Env -> Exp -> Err Val
+eval env e = ---- errIn ("eval" +++ prt e +++ "in" +++ prEnv env) $ 
+             case e of
+  Vr x    -> lookupVar env x
+  Q m c   -> return $ VCn (m,c)
+  QC m c  -> return $ VCn (m,c) ---- == Q ?
+  Sort c  -> return $ VType --- the only sort is Type
+  App f a -> join $ liftM2 app (eval env f) (eval env a)
+  RecType xs -> do xs <- mapM (\(l,e) -> eval env e >>= \e -> return (l,e)) xs
+                   return (VRecType xs)
+  _ -> return $ VClos env e
+
+eqVal :: Int -> Val -> Val -> Err [(Val,Val)]
+eqVal k u1 u2 = ---- errIn (prt u1 +++ "<>" +++ prBracket (show k) +++ prt u2) $ 
+                do
+  w1 <- whnf u1
+  w2 <- whnf u2 
+  let v = VGen k
+  case (w1,w2) of
+    (VApp f1 a1, VApp f2 a2) -> liftM2 (++) (eqVal k f1 f2) (eqVal k a1 a2)
+    (VClos env1 (Abs _ x1 e1), VClos env2 (Abs _ x2 e2)) ->
+      eqVal (k+1) (VClos ((x1,v x1):env1) e1) (VClos ((x2,v x1):env2) e2)
+    (VClos env1 (Prod _ x1 a1 e1), VClos env2 (Prod _ x2 a2 e2)) ->
+      liftM2 (++) 
+        (eqVal k     (VClos            env1  a1) (VClos            env2  a2))
+        (eqVal (k+1) (VClos ((x1,v x1):env1) e1) (VClos ((x2,v x1):env2) e2))
+    (VGen i _, VGen j _) -> return [(w1,w2) | i /= j]
+    (VCn (_, i), VCn (_,j)) -> return [(w1,w2) | i /= j] 
+    --- thus ignore qualifications; valid because inheritance cannot
+    --- be qualified. Simplifies annotation. AR 17/3/2005 
+    _ -> return [(w1,w2) | w1 /= w2]
+-- invariant: constraints are in whnf
+
+checkType :: Theory -> TCEnv -> Exp -> Err (AExp,[(Val,Val)])
+checkType th tenv e = checkExp th tenv e vType
+
+checkExp :: Theory -> TCEnv -> Exp -> Val -> Err (AExp, [(Val,Val)])
+checkExp th tenv@(k,rho,gamma) e ty = do
+  typ <- whnf ty
+  let v = VGen k
+  case e of
+    Meta m -> return $ (AMeta m typ,[])
+
+    Abs _ x t -> case typ of
+      VClos env (Prod _ y a b) -> do
+	a' <- whnf $ VClos env a ---
+	(t',cs) <- checkExp th 
+                           (k+1,(x,v x):rho, (x,a'):gamma) t (VClos ((y,v x):env) b)
+	return (AAbs x a' t', cs)
+      _ -> Bad (render (text "function type expected for" <+> ppTerm Unqualified 0 e <+> text "instead of" <+> ppValue Unqualified 0 typ))
+
+    Prod _ x a b -> do
+      testErr (typ == vType) "expected Type"
+      (a',csa) <- checkType th tenv a
+      (b',csb) <- checkType th (k+1, (x,v x):rho, (x,VClos rho a):gamma) b
+      return (AProd x a' b', csa ++ csb)
+
+    R xs -> 
+      case typ of
+        VRecType ys -> do case [l | (l,_) <- ys, isNothing (lookup l xs)] of
+                            [] -> return ()
+                            ls -> fail (render (text "no value given for label:" <+> fsep (punctuate comma (map ppLabel ls))))
+                          r <- mapM (checkAssign th tenv ys) xs
+                          let (xs,css) = unzip r
+                          return (AR xs, concat css)
+        _           -> Bad (render (text "record type expected for" <+> ppTerm Unqualified 0 e <+> text "instead of" <+> ppValue Unqualified 0 typ))
+
+    P r l -> do (r',cs) <- checkExp th tenv r (VRecType [(l,typ)])
+                return (AP r' l typ,cs)
+
+    _ -> checkInferExp th tenv e typ
+
+checkInferExp :: Theory -> TCEnv -> Exp -> Val -> Err (AExp, [(Val,Val)])
+checkInferExp th tenv@(k,_,_) e typ = do
+  (e',w,cs1) <- inferExp th tenv e
+  cs2 <- eqVal k w typ
+  return (e',cs1 ++ cs2)
+      
+inferExp :: Theory -> TCEnv -> Exp -> Err (AExp, Val, [(Val,Val)])
+inferExp th tenv@(k,rho,gamma) e = case e of
+   Vr x -> mkAnnot (AVr x) $ noConstr $ lookupVar gamma x
+   Q m c | m == cPredefAbs && isPredefCat c
+                     -> return (ACn (m,c) vType, vType, [])
+         | otherwise -> mkAnnot (ACn (m,c)) $ noConstr $ lookupConst th (m,c)
+   QC m c -> mkAnnot (ACn (m,c)) $ noConstr $ lookupConst th (m,c) ----
+   EInt i -> return (AInt i, valAbsInt, [])
+   EFloat i -> return (AFloat i, valAbsFloat, [])
+   K i -> return (AStr i, valAbsString, [])
+   Sort _ -> return (AType, vType, [])
+   RecType xs -> do r <- mapM (checkLabelling th tenv) xs
+                    let (xs,css) = unzip r
+                    return (ARecType xs, vType, concat css)
+   App f t -> do
+    (f',w,csf) <- inferExp th tenv f 
+    typ <- whnf w
+    case typ of
+      VClos env (Prod _ x a b) -> do
+        (a',csa) <- checkExp th tenv t (VClos env a)
+	b' <- whnf $ VClos ((x,VClos rho t):env) b
+	return $ (AApp f' a' b', b', csf ++ csa)
+      _ -> Bad (render (text "Prod expected for function" <+> ppTerm Unqualified 0 f <+> text "instead of" <+> ppValue Unqualified 0 typ))
+   _ -> Bad (render (text "cannot infer type of expression" <+> ppTerm Unqualified 0 e))
+
+checkLabelling :: Theory -> TCEnv -> Labelling -> Err (ALabelling, [(Val,Val)])
+checkLabelling th tenv (lbl,typ) = do
+  (atyp,cs) <- checkType th tenv typ
+  return ((lbl,atyp),cs)
+
+checkAssign :: Theory -> TCEnv -> [(Label,Val)] -> Assign -> Err (AAssign, [(Val,Val)])
+checkAssign th tenv@(k,rho,gamma) typs (lbl,(Just typ,exp)) = do
+  (atyp,cs1) <- checkType th tenv typ
+  val <- eval rho typ
+  cs2 <- case lookup lbl typs of
+           Nothing   -> return []
+           Just val0 -> eqVal k val val0
+  (aexp,cs3) <- checkExp th tenv exp val
+  return ((lbl,(val,aexp)),cs1++cs2++cs3)
+checkAssign th tenv@(k,rho,gamma) typs (lbl,(Nothing,exp)) = do
+  case lookup lbl typs of
+    Nothing  -> do (aexp,val,cs) <- inferExp th tenv exp
+                   return ((lbl,(val,aexp)),cs)
+    Just val -> do (aexp,cs) <- checkExp th tenv exp val
+                   return ((lbl,(val,aexp)),cs)
+
+checkBranch :: Theory -> TCEnv -> Equation -> Val -> Err (([Exp],AExp),[(Val,Val)])
+checkBranch th tenv b@(ps,t) ty = errIn ("branch" +++ show b) $ 
+                                  chB tenv' ps' ty 
+ where 
+
+  (ps',_,rho2,k') = ps2ts k ps
+  tenv' = (k, rho2++rho, gamma) ---- k' ?
+  (k,rho,gamma) = tenv
+
+  chB tenv@(k,rho,gamma) ps ty = case ps of
+    p:ps2 -> do
+      typ <- whnf ty
+      case typ of
+        VClos env (Prod _ y a b) -> do
+	  a' <- whnf $ VClos env a
+          (p', sigma, binds, cs1) <- checkP tenv p y a'
+          let tenv' = (length binds, sigma ++ rho, binds ++ gamma)
+          ((ps',exp),cs2) <- chB tenv' ps2 (VClos ((y,p'):env) b)
+	  return ((p:ps',exp), cs1 ++ cs2) -- don't change the patt
+        _ -> Bad (render (text "Product expected for definiens" <+> ppTerm Unqualified 0 t <+> text "instead of" <+> ppValue Unqualified 0 typ))
+    [] -> do
+      (e,cs) <- checkExp th tenv t ty
+      return (([],e),cs)
+  checkP env@(k,rho,gamma) t x a = do
+     (delta,cs) <- checkPatt th env t a
+     let sigma = [(x, VGen i x) | ((x,_),i) <- zip delta [k..]]
+     return (VClos sigma t, sigma, delta, cs)
+
+  ps2ts k = foldr p2t ([],0,[],k) 
+  p2t p (ps,i,g,k) = case p of
+     PW      -> (Meta i : ps, i+1,g,k) 
+     PV x    -> (Vr x   : ps, i, upd x k g,k+1)
+     PString s -> (K s : ps, i, g, k)
+     PInt n -> (EInt n : ps, i, g, k)
+     PFloat n -> (EFloat n : ps, i, g, k)
+     PP m c xs -> (mkApp (Q m c) xss : ps, j, g',k') 
+                    where (xss,j,g',k') = foldr p2t ([],i,g,k) xs
+     _ -> error $ render (text "undefined p2t case" <+> ppPatt Unqualified 0 p <+> text "in checkBranch")
+
+  upd x k g = (x, VGen k x) : g --- hack to recognize pattern variables
+
+
+checkPatt :: Theory -> TCEnv -> Exp -> Val -> Err (Binds,[(Val,Val)])
+checkPatt th tenv exp val = do
+  (aexp,_,cs) <- checkExpP tenv exp val
+  let binds = extrBinds aexp
+  return (binds,cs)
+ where
+   extrBinds aexp = case aexp of
+     AVr i v    -> [(i,v)]
+     AApp f a _ -> extrBinds f ++ extrBinds a
+     _ -> [] -- no other cases are possible
+
+--- ad hoc, to find types of variables
+   checkExpP tenv@(k,rho,gamma) exp val = case exp of
+     Meta m -> return $ (AMeta m val, val, [])
+     Vr x   -> return $ (AVr   x val, val, [])
+     EInt i -> return (AInt i, valAbsInt, [])
+     EFloat i -> return (AFloat i, valAbsFloat, [])
+     K s    -> return (AStr s, valAbsString, [])
+
+     Q m c  -> do
+       typ <- lookupConst th (m,c)
+       return $ (ACn (m,c) typ, typ, [])
+     QC m c  -> do
+       typ <- lookupConst th (m,c)
+       return $ (ACn (m,c) typ, typ, []) ----
+     App f t -> do
+       (f',w,csf) <- checkExpP tenv f val
+       typ <- whnf w
+       case typ of
+         VClos env (Prod _ x a b) -> do
+           (a',_,csa) <- checkExpP tenv t (VClos env a)
+	   b' <- whnf $ VClos ((x,VClos rho t):env) b
+	   return $ (AApp f' a' b', b', csf ++ csa)
+         _ -> Bad (render (text "Prod expected for function" <+> ppTerm Unqualified 0 f <+> text "instead of" <+> ppValue Unqualified 0 typ))
+     _ -> Bad (render (text "cannot typecheck pattern" <+> ppTerm Unqualified 0 exp))
+
+-- auxiliaries
+
+noConstr :: Err Val -> Err (Val,[(Val,Val)])
+noConstr er = er >>= (\v -> return (v,[]))
+
+mkAnnot :: (Val -> AExp) -> Err (Val,[(Val,Val)]) -> Err (AExp,Val,[(Val,Val)])
+mkAnnot a ti = do
+  (v,cs) <- ti
+  return (a v, v, cs)
+
diff --git a/src/compiler/GF/Compile/Abstract/TypeCheck.hs b/src/compiler/GF/Compile/Abstract/TypeCheck.hs
new file mode 100644
index 000000000..2632c54dd
--- /dev/null
+++ b/src/compiler/GF/Compile/Abstract/TypeCheck.hs
@@ -0,0 +1,83 @@
+----------------------------------------------------------------------
+-- |
+-- Module      : TypeCheck
+-- Maintainer  : AR
+-- Stability   : (stable)
+-- Portability : (portable)
+--
+-- > CVS $Date: 2005/09/15 16:22:02 $ 
+-- > CVS $Author: aarne $
+-- > CVS $Revision: 1.16 $
+--
+-- (Description of the module)
+-----------------------------------------------------------------------------
+
+module GF.Compile.Abstract.TypeCheck (-- * top-level type checking functions; TC should not be called directly.
+		  checkContext,
+		  checkTyp,
+		  checkDef,
+		  checkConstrs,
+		 ) where
+
+import GF.Data.Operations
+
+import GF.Infra.CheckM
+import GF.Grammar
+import GF.Grammar.Lookup
+import GF.Grammar.Unify
+import GF.Compile.Refresh
+import GF.Compile.Abstract.Compute
+import GF.Compile.Abstract.TC
+
+import Text.PrettyPrint
+import Control.Monad (foldM, liftM, liftM2)
+
+-- | invariant way of creating TCEnv from context
+initTCEnv gamma = 
+  (length gamma,[(x,VGen i x) | ((x,_),i) <- zip gamma [0..]], gamma) 
+
+-- interface to TC type checker
+
+type2val :: Type -> Val
+type2val = VClos []
+
+cont2exp :: Context -> Exp
+cont2exp c = mkProd c eType [] -- to check a context
+
+cont2val :: Context -> Val
+cont2val = type2val . cont2exp
+
+-- some top-level batch-mode checkers for the compiler
+
+justTypeCheck :: SourceGrammar -> Exp -> Val -> Err Constraints
+justTypeCheck gr e v = do
+  (_,constrs0) <- checkExp (grammar2theory gr) (initTCEnv []) e v
+  (constrs1,_) <- unifyVal constrs0
+  return $ filter notJustMeta constrs1
+
+notJustMeta (c,k) = case (c,k) of
+    (VClos g1 (Meta m1), VClos g2 (Meta m2)) -> False
+    _ -> True
+
+grammar2theory :: SourceGrammar -> Theory
+grammar2theory gr (m,f) = case lookupFunType gr m f of
+  Ok t -> return $ type2val t
+  Bad s -> case lookupCatContext gr m f of
+    Ok cont -> return $ cont2val cont
+    _ -> Bad s
+
+checkContext :: SourceGrammar -> Context -> [Message]
+checkContext st = checkTyp st . cont2exp
+
+checkTyp :: SourceGrammar -> Type -> [Message]
+checkTyp gr typ = err (\x -> [text x]) ppConstrs $ justTypeCheck gr typ vType
+
+checkDef :: SourceGrammar -> Fun -> Type -> [Equation] -> [Message]
+checkDef gr (m,fun) typ eqs = err (\x -> [text x]) ppConstrs $ do
+  bcs <- mapM (\b -> checkBranch (grammar2theory gr) (initTCEnv []) b (type2val typ)) eqs
+  let (bs,css) = unzip bcs
+  (constrs,_) <- unifyVal (concat css)
+  return $ filter notJustMeta constrs
+
+checkConstrs :: SourceGrammar -> Cat -> [Ident] -> [String]
+checkConstrs gr cat _ = [] ---- check constructors!