changed names of resource-1.3; added a note on homepage on release

1 files changed, 292 insertions, 0 deletions

diff --git a/src/GF/Compile/TC.hs b/src/GF/Compile/TC.hs
new file mode 100644
index 000000000..c0c8a83ae
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+++ b/src/GF/Compile/TC.hs
@@ -0,0 +1,292 @@
+----------------------------------------------------------------------
+-- |
+-- 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.TC (AExp(..),
+	   Theory,
+	   checkExp,
+	   inferExp,
+           checkEqs,
+	   eqVal,
+	   whnf
+	  ) where
+
+import GF.Data.Operations
+import GF.Grammar.Predef
+import GF.Grammar.Abstract
+
+import Control.Monad
+import Data.List (sortBy)
+
+data AExp =
+     AVr   Ident Val 
+   | ACn   QIdent Val
+   | AType 
+   | AInt  Integer 
+   | AFloat Double
+   | AStr  String
+   | AMeta MetaSymb Val
+   | AApp  AExp AExp Val 
+   | AAbs  Ident Val AExp 
+   | AProd Ident AExp AExp 
+   | AEqs  [([Exp],AExp)] --- not used
+   | AData Val
+  deriving (Eq,Show)
+
+type Theory = QIdent -> Err Val
+
+lookupConst :: Theory -> QIdent -> Err Val
+lookupConst th f = th f
+
+lookupVar :: Env -> Ident -> Err Val
+lookupVar g x = maybe (prtBad "unknown variable" 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)
+  _ -> 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,[])
+    EData -> return $ (AData 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)
+      _ -> prtBad ("function type expected for" +++ prt e +++ "instead of") typ
+
+-- {- --- to get deprec when checkEqs works (15/9/2005)
+    Eqs es -> do
+      bcs <- mapM (\b -> checkBranch th tenv b typ) es
+      let (bs,css) = unzip bcs
+      return (AEqs bs, concat css) 
+-- - }
+    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)
+
+    _ -> 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, [])
+   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)
+      _ -> prtBad ("Prod expected for function" +++ prt f +++ "instead of") typ
+   _ -> prtBad "cannot infer type of expression" e
+
+checkEqs :: Theory -> TCEnv -> (Fun,Trm) -> Val -> Err [(Val,Val)]
+checkEqs th tenv@(k,rho,gamma) (fun@(m,f),def) val = case def of
+  Eqs es -> liftM concat $ mapM checkBranch es
+  _      -> liftM snd $ checkExp th tenv def val
+ where
+  checkBranch (ps,df) = 
+   let
+      (ps',_,vars) = foldr p2t ([],0,[]) ps
+      fps        = mkApp (Q m f) ps'
+   in errIn ("branch" +++ prt fps) $ do
+    (aexp, typ, cs1) <- inferExp th tenv fps
+    let
+      bds = binds vars aexp 
+      tenv' = (k, rho, bds ++ gamma) 
+    (_,cs2)  <- errIn (show bds) $ checkExp th tenv' df typ
+    return $ (cs1 ++ cs2)
+  p2t p (ps,i,g) = case p of
+     PW      -> (Meta (MetaSymb i) : ps, i+1,        g) 
+     PV IW   -> (Meta (MetaSymb i) : ps, i+1,        g) 
+     PV x    -> (Meta (MetaSymb i) : ps, i+1,upd x i g)
+     PString s -> (            K s : ps, i,          g)
+     PInt n -> (EInt n : ps, i, g)
+     PFloat n -> (EFloat n : ps, i, g)
+     PP m c xs -> (mkApp (qq (m,c)) xss : ps, i', g') 
+                    where (xss,i',g') = foldr p2t ([],i,g) xs
+     _ -> error $ "undefined p2t case" +++ prt p +++ "in checkBranch"
+  upd x i g = (x,i) : g --- to annotate pattern variables: treat as metas
+  
+  -- notice: in vars, the sequence 0.. is sorted. In subst aexp, all
+  -- this occurs and nothing else.
+  binds vars aexp = [(x,v) | ((x,_),v) <- zip vars metas] where
+    metas = map snd $ sortBy (\ (x,_) (y,_) -> compare x y) $ subst aexp
+  subst aexp = case aexp of
+   AMeta (MetaSymb i) v -> [(i,v)]
+   AApp  c a _ -> subst c ++ subst a
+   _ -> [] -- never matter in patterns
+
+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
+        _ -> prtBad ("Product expected for definiens" +++prt t +++ "instead of") 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 (MetaSymb i) : ps, i+1,g,k) 
+     PV IW   -> (Meta (MetaSymb 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 (qq (m,c)) xss : ps, j, g',k') 
+                    where (xss,j,g',k') = foldr p2t ([],i,g,k) xs
+     _ -> error $ "undefined p2t case" +++ prt p +++ "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)
+         _ -> prtBad ("Prod expected for function" +++ prt f +++ "instead of") typ
+     _ -> prtBad "cannot typecheck pattern" 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)
+