diff --git a/src/Elab.hs b/src/Elab.hs
index 0565b92..42f709c 100644
--- a/src/Elab.hs
+++ b/src/Elab.hs
@@ -31,7 +31,6 @@ import Prettyprinter
 
 import Syntax.Pretty
 import Syntax
-import Syntax.Subst
 
 infer :: P.Expr -> ElabM (Term, NFType)
 infer (P.Span ex a b) = withSpan a b $ infer ex
diff --git a/src/Elab/Eval.hs b/src/Elab/Eval.hs
index 0dc4c3d..83cd0b5 100644
--- a/src/Elab/Eval.hs
+++ b/src/Elab/Eval.hs
@@ -37,12 +37,11 @@ import System.IO.Unsafe
 
 import {-# SOURCE #-} Elab.WiredIn
 import Data.List (sortOn)
-import Syntax.Subst
+import Data.Map.Strict (Map)
 
 eval :: Term -> ElabM Value
 eval t = asks (flip eval' t)
 
-
 -- everywhere force
 zonkIO :: Value -> IO Value
 zonkIO (VNe hd sp) = do
@@ -93,7 +92,9 @@ zonkIO (VHComp a b c d) = hComp <$> zonkIO a <*> zonkIO b <*> zonkIO c <*> zonkI
 zonkIO (VGlueTy a phi ty e)   = glueType <$> zonkIO a <*> zonkIO phi <*> zonkIO ty <*> zonkIO e
 zonkIO (VGlue a phi ty e t x) = glueElem <$> zonkIO a <*> zonkIO phi <*> zonkIO ty <*> zonkIO e <*> zonkIO t <*> zonkIO x
 zonkIO (VUnglue a phi ty e x) = unglue   <$> zonkIO a <*> zonkIO phi <*> zonkIO ty <*> zonkIO e <*> zonkIO x
-zonkIO (VCase t x xs) = VCase <$> zonkIO t <*> zonkIO x <*> pure xs
+zonkIO (VCase env t x xs) = do
+  env' <- emptyEnv
+  evalCase env'{getEnv = env} . (@@) <$> zonkIO t <*> zonkIO x <*> pure xs
 
 zonkSp :: Projection -> IO Projection
 zonkSp (PApp p x) = PApp p <$> zonkIO x
@@ -184,7 +185,9 @@ eval' e (Case range sc xs) = evalCase e (eval' e range @@) (force (eval' e sc))
 evalCase :: ElabEnv -> (Value -> Value) -> Value -> [(Term, Term)] -> Value
 evalCase _ _ sc [] = error $ "unmatched pattern for value: " ++ show (prettyTm (quote sc))
 
-evalCase env rng (VHComp a phi u a0) cases =
+evalCase env rng (VSystem fs) cases = VSystem (fmap (flip (evalCase env rng) cases) fs)
+
+evalCase env rng (VHComp a phi u a0) cases = 
   comp (fun \i -> rng (v i)) phi (system \i is1 -> evalCase env rng (u @@ i @@ is1) cases)
          (VInc (rng a) phi (evalCase env rng (outS a0 phi (u @@ VI0) a0) cases))
   where
@@ -200,7 +203,7 @@ evalCase env rng (val@(VNe (HPCon _ _ x) sp)) ((Con x', k):xs)
   | x == x'   = foldl applProj (eval' env k) sp
   | otherwise = evalCase env rng val xs
 
-evalCase _ rng sc xs = VCase (fun rng) sc xs
+evalCase env rng sc xs = VCase (getEnv env) (fun rng) sc xs
 
 
 data NotEqual = NotEqual Value Value
@@ -287,7 +290,7 @@ unify' topa topb = join $ go <$> forceIO topa <*> forceIO topb where
   go (VSystem sys) rhs = goSystem unify' sys rhs
   go rhs (VSystem sys) = goSystem (flip unify') sys rhs
 
-  go (VCase _ a b) (VCase _ a' b') = do
+  go (VCase _ _ a b) (VCase _ _ a' b') = do
     unify' a a'
     let go a b = join $ unify' <$> eval (snd a) <*> eval (snd b)
     zipWithM_ go (sortOn fst b) (sortOn fst b')
@@ -465,7 +468,7 @@ checkScope s (VGlueTy a phi ty eq) = traverse_ (checkScope s) [a, phi, ty, eq]
 checkScope s (VGlue a phi ty eq inv x) = traverse_ (checkScope s) [a, phi, ty, eq, inv, x]
 checkScope s (VUnglue a phi ty eq vl) = traverse_ (checkScope s) [a, phi, ty, eq, vl]
 
-checkScope s (VCase _ v _) = checkScope s v
+checkScope s (VCase _ _ v _) = checkScope s v
 
 checkSpine :: Set Name -> Seq Projection -> ElabM [Name]
 checkSpine scope (PApp Ex (VVar n@Bound{}) Seq.:<| xs)
@@ -479,3 +482,133 @@ newtype NonLinearSpine = NonLinearSpine { getDupeName :: Name }
 
 newtype SpineProjection = SpineProj { getSpineProjection :: Projection }
   deriving (Show, Typeable, Exception)
+
+substituteIO :: Map.Map Name Value -> Value -> IO Value
+substituteIO sub = substituteIO . force where
+  substituteIO (VNe hd sp) = do
+    sp' <- traverse (substituteSp sub) sp
+    case hd of
+      HMeta (mvCell -> cell) -> do
+        solved <- liftIO $ readIORef cell
+        case solved of
+          Just vl -> substituteIO $ foldl applProj vl sp'
+          Nothing -> pure $ VNe hd sp'
+      HVar v ->
+        case Map.lookup v sub of
+          Just vl -> substituteIO $ foldl applProj vl sp'
+          Nothing -> pure $ VNe hd sp'
+      hd -> pure $ VNe hd sp'
+
+  substituteIO (GluedVl h sp vl) = GluedVl h <$> traverse (substituteSp sub) sp <*> substituteIO vl
+
+  substituteIO (VLam p (Closure s k)) = pure $ VLam p (Closure s (substitute (Map.delete s sub) . k))
+  substituteIO (VPi p d (Closure s k)) = VPi p <$> substituteIO d <*> pure (Closure s (substitute (Map.delete s sub) . k))
+  substituteIO (VSigma d (Closure s k)) = VSigma <$> substituteIO d <*> pure (Closure s (substitute (Map.delete s sub) . k))
+  substituteIO (VPair a b) = VPair <$> substituteIO a <*> substituteIO b
+
+  substituteIO (VPath line x y) = VPath <$> substituteIO line <*> substituteIO x <*> substituteIO y
+  substituteIO (VLine line x y f) = VLine <$> substituteIO line <*> substituteIO x <*> substituteIO y <*> substituteIO f
+
+  -- Sorts
+  substituteIO VType = pure VType
+  substituteIO VTypeω = pure VTypeω
+
+  substituteIO VI = pure VI
+  substituteIO VI0 = pure VI0
+  substituteIO VI1 = pure VI1
+
+  substituteIO (VIAnd x y) = iand <$> substituteIO x <*> substituteIO y
+  substituteIO (VIOr x y) = ior <$> substituteIO x <*> substituteIO y
+  substituteIO (VINot x) = inot <$> substituteIO x
+
+  substituteIO (VIsOne x) = VIsOne <$> substituteIO x
+  substituteIO VItIsOne = pure VItIsOne
+
+  substituteIO (VPartial x y)  = VPartial <$> substituteIO x <*> substituteIO y
+  substituteIO (VPartialP x y) = VPartialP <$> substituteIO x <*> substituteIO y
+  substituteIO (VSystem fs) = do
+    t <- for (Map.toList fs) $ \(a, b) -> (,) <$> substituteIO a <*> substituteIO b
+    pure (mkVSystem (Map.fromList t))
+  substituteIO (VSub a b c) = VSub <$> substituteIO a <*> substituteIO b <*> substituteIO c
+  substituteIO (VInc a b c) = VInc <$> substituteIO a <*> substituteIO b <*> substituteIO c
+  substituteIO (VComp a b c d) = comp <$> substituteIO a <*> substituteIO b <*> substituteIO c <*> substituteIO d
+  substituteIO (VHComp a b c d) = hComp <$> substituteIO a <*> substituteIO b <*> substituteIO c <*> substituteIO d
+
+  substituteIO (VGlueTy a phi ty e)   = glueType <$> substituteIO a <*> substituteIO phi <*> substituteIO ty <*> substituteIO e
+  substituteIO (VGlue a phi ty e t x) = glueElem <$> substituteIO a <*> substituteIO phi <*> substituteIO ty <*> substituteIO e <*> substituteIO t <*> substituteIO x
+  substituteIO (VUnglue a phi ty e x) = unglue   <$> substituteIO a <*> substituteIO phi <*> substituteIO ty <*> substituteIO e <*> substituteIO x
+  substituteIO (VCase env t x xs) = VCase env <$> substituteIO t <*> substituteIO x <*> pure xs
+
+substitute :: Map Name Value -> Value -> Value
+substitute sub = unsafePerformIO . substituteIO sub
+
+substituteSp :: Map Name Value -> Projection -> IO Projection
+substituteSp sub (PApp p x) = PApp p <$> substituteIO sub x
+substituteSp sub (PIElim l x y i) = PIElim <$> substituteIO sub l <*> substituteIO sub x <*> substituteIO sub y <*> substituteIO sub i
+substituteSp sub (POuc a phi u) = POuc <$> substituteIO sub a <*> substituteIO sub phi <*> substituteIO sub u
+substituteSp _ PProj1 = pure PProj1
+substituteSp _ PProj2 = pure PProj2
+
+mkVSystem :: Map.Map Value Value -> Value
+mkVSystem vals =
+  let map' = Map.fromList (map (\(a, b) -> (force a, b)) (Map.toList vals)) in
+  case Map.lookup VI1 map' of
+    Just x -> x
+    Nothing -> VSystem (Map.filterWithKey (\k _ -> k /= VI0) map')
+
+forceIO :: MonadIO m => Value -> m Value
+forceIO mv@(VNe (HMeta (mvCell -> cell)) args) = do
+  solved <- liftIO $ readIORef cell
+  case solved of
+    Just vl -> forceIO (foldl applProj vl args)
+    Nothing -> pure mv
+forceIO vl@(VSystem fs) =
+  case Map.lookup VI1 fs of
+    Just x -> forceIO x
+    Nothing -> pure vl
+forceIO (GluedVl _ _ vl) = forceIO vl
+forceIO (VComp line phi u a0) = comp <$> forceIO line <*> forceIO phi <*> pure u <*> pure a0
+forceIO (VCase env rng v vs) = do
+  env' <- liftIO emptyEnv
+  evalCase env'{getEnv=env} . (@@) <$> forceIO rng <*> forceIO v <*> pure vs
+forceIO x = pure x
+
+applProj :: Value -> Projection -> Value
+applProj fun (PApp p arg)     = vApp p fun arg
+applProj fun (PIElim l x y i) = ielim l x y fun i
+applProj fun (POuc a phi u)   = outS a phi u fun
+applProj fun PProj1           = vProj1 fun
+applProj fun PProj2           = vProj2 fun
+
+force :: Value -> Value
+force = unsafePerformIO . forceIO
+
+vApp :: HasCallStack => Plicity -> Value -> Value -> Value
+vApp p (VLam p' k) arg
+  | p == p'   = clCont k arg
+  | otherwise = error $ "wrong plicity " ++ show p ++ " vs " ++ show p' ++ " in app " ++ show (App p (quote (VLam p' k)) (quote arg))
+vApp p (VNe h sp) arg    = VNe h (sp Seq.:|> PApp p arg)
+vApp p (GluedVl h sp vl) arg = GluedVl h (sp Seq.:|> PApp p arg) (vApp p vl arg)
+vApp p (VSystem fs) arg = VSystem (fmap (flip (vApp p) arg) fs)
+vApp p (VInc (VPi _ _ (Closure _ r)) phi f) arg = VInc (r (vApp p f arg)) phi (vApp p f arg)
+vApp _ x _             = error $ "can't apply " ++ show (prettyTm (quote x))
+
+(@@) :: HasCallStack => Value -> Value -> Value
+(@@) = vApp Ex
+infixl 9 @@
+
+vProj1 :: HasCallStack => Value -> Value
+vProj1 (VPair a _) = a
+vProj1 (VNe h sp) = VNe h (sp Seq.:|> PProj1)
+vProj1 (GluedVl h sp vl) = GluedVl h (sp Seq.:|> PProj1) (vProj1 vl)
+vProj1 (VSystem fs) = VSystem (fmap vProj1 fs)
+vProj1 (VInc (VSigma a _) b c) = VInc a b (vProj1 c)
+vProj1 x = error $ "can't proj1 " ++ show (prettyTm (quote x))
+
+vProj2 :: HasCallStack => Value -> Value
+vProj2 (VPair _ b) = b
+vProj2 (VNe h sp)  = VNe h (sp Seq.:|> PProj2)
+vProj2 (GluedVl h sp vl) = GluedVl h (sp Seq.:|> PProj2) (vProj2 vl)
+vProj2 (VSystem fs) = VSystem (fmap vProj2 fs)
+vProj2 (VInc (VSigma _ (Closure _ r)) b c) = VInc (r (vProj1 c)) b (vProj2 c)
+vProj2 x = error $ "can't proj2 " ++ show (prettyTm (quote x))
\ No newline at end of file
diff --git a/src/Elab/WiredIn.hs b/src/Elab/WiredIn.hs
index 1fa9ff4..37002e3 100644
--- a/src/Elab/WiredIn.hs
+++ b/src/Elab/WiredIn.hs
@@ -25,7 +25,6 @@ import Syntax.Pretty (prettyTm)
 import Syntax
 
 import System.IO.Unsafe
-import Syntax.Subst
 
 wiType :: WiredIn -> NFType
 wiType WiType     = VType
@@ -94,6 +93,9 @@ fun, line :: (Value -> Value) -> Value
 fun k = VLam P.Ex $ Closure (Bound "x" 0) (k . force)
 line k = VLam P.Ex $ Closure (Bound "i" 0) (k . force)
 
+fun' :: String -> (Value -> Value) -> Value
+fun' x k = VLam P.Ex $ Closure (Bound (T.pack x) 0) (k . force)
+
 forallI :: (Value -> Value) -> Value
 forallI k = VLam P.Im $ Closure (Bound "x" 0) (k . force)
 
@@ -196,7 +198,7 @@ ielim line left right fn i =
         VNe n sp -> VNe n (sp Seq.:|> PIElim line left right i)
         VSystem map -> VSystem (fmap (flip (ielim line left right) i) map)
         VInc (VPath _ _ _) _ u -> ielim line left right u i
-        VCase r x xs -> VCase r x (fmap (fmap (flip (IElim (quote line) (quote left) (quote right)) (quote i))) xs)
+        VCase env r x xs -> VCase env r x (fmap (fmap (flip (IElim (quote line) (quote left) (quote right)) (quote i))) xs)
         _ -> error $ "can't ielim " ++ show (prettyTm (quote fn))
 
 outS :: HasCallStack => NFSort -> NFEndp -> Value -> Value -> Value
@@ -207,11 +209,12 @@ outS _ VI0 _  x            = x
 
 outS a phi u  (GluedVl x sp vl) = GluedVl x (sp Seq.:|> POuc a phi u) (outS a phi u vl)
 outS a phi u  (VNe x sp) = VNe x (sp Seq.:|> POuc a phi u)
+outS a phi u (VSystem fs) = VSystem (fmap (outS a phi u) fs)
 outS _ _ _ v             = error $ "can't outS " ++ show (prettyTm (quote v))
 
 -- Composition
-comp :: NFLine -> NFEndp -> Value -> Value -> Value
-comp _a VI1 u _a0 = u @@ VI1 @@ VItIsOne
+comp :: HasCallStack => NFLine -> NFEndp -> Value -> Value -> Value
+comp _a VI1 u _a0 =  u @@ VI1 @@ VItIsOne
 comp a psi@phi u incA0@(compOutS (a @@ VI1) phi (u @@ VI1 @@ VItIsOne) -> a0) =
   case force $ a @@ VVar (Bound (T.pack "i") (negate 1)) of
     VPi{} ->
@@ -252,28 +255,29 @@ comp a psi@phi u incA0@(compOutS (a @@ VI1) phi (u @@ VI1 @@ VItIsOne) -> a0) =
                                                         , (inot j, u' i)]))
             (VInc (a' VI0 @@ VI0 @@ j) phi (ielim (a' VI0 @@ VI0) (u' VI0) (v' VI0) a0 j))
 
-    VGlueTy theBase thePhi theTypes theEquivs ->
+    VGlueTy _ thePhi theTypes theEquivs ->
       let
         b = u
         b0 = a0
+        fam = a
       in
       let
-        base i   = substitute (Map.singleton (Bound "i" (negate 1)) i) theBase
+        base i   = let VGlueTy b _ _ _ = forceAndGlue (fam @@ i) in b
         phi i    = substitute (Map.singleton (Bound "i" (negate 1)) i) thePhi
-        types i  = substitute (Map.singleton (Bound "i" (negate 1)) i) theTypes
+        types i  = substitute (Map.singleton (Bound "i" (negate 1)) i) theTypes @@ VItIsOne
         equivs i = substitute (Map.singleton (Bound "i" (negate 1)) i) theEquivs
 
-        a i = fun \u -> unglue (base i) (phi i) (types i @@ u) (equivs i @@ u) (b @@ i @@ u)
+        a i u = unglue (base i) (phi i) (types i @@ u) (equivs i) (b @@ i @@ u)
         a0 = unglue (base VI0) (phi VI0) (types VI0) (equivs VI0) b0
 
         del = faceForall phi
-        a1' = comp (line base) psi (line a) (VInc (base VI0) (phi VI0) a0)
-        t1' = comp (line types) psi (line (b @@)) (VInc (base VI0) (phi VI0) b0)
+        a1' = comp (line base)  psi (system a) (VInc (base VI0) psi a0)
+        t1' = comp (line (const (types VI0))) psi (line (b @@)) (VInc (base VI0) psi b0)
 
         (omega_st, omega_t, omega_rep) = pres types base equivs psi (b @@) b0
         omega = outS omega_t psi omega_rep omega_st
 
-        (t1alpha_st, t1a_t, t1a_rep) = opEquiv (base VI1) (types VI1 @@ VItIsOne) (equivs VI1 @@ VItIsOne) (del `ior` psi) (fun ts) (fun ps) a1'
+        (t1alpha_st, t1a_t, t1a_rep) = opEquiv (base VI1) (types VI1) (equivs VI1 @@ VItIsOne) (del `ior` psi) (fun ts) (fun ps) a1'
         t1alpha = outS t1a_t (del `ior` psi) t1a_rep t1alpha_st
 
         (t1, alpha) = (vProj1 t1alpha, vProj2 t1alpha)
@@ -282,17 +286,18 @@ comp a psi@phi u incA0@(compOutS (a @@ VI1) phi (u @@ VI1 @@ VItIsOne) -> a0) =
         ps _isone = mkVSystem . Map.fromList $ [(del, omega), (psi, VLine (line (const (base VI1))) a1' a1' (fun (const a1')))]
 
         a1 = comp
-          (fun (const (base VI1 @@ VItIsOne)))
+          (fun (const (base VI1)))
           (phi VI1 `ior` psi)
           (system \j _u -> mkVSystem (Map.fromList [ (phi VI1, ielim (base VI1) a1' (vProj1 (equivs VI1 @@ VItIsOne)) alpha j)
-                                                   , (psi, a VI1)]))
-          a1'
+                                                   , (psi, a VI1 VItIsOne)]))
+          (VInc (base VI1) (phi VI1 `ior` psi) a1')
         b1 = glueElem (base VI1) (phi VI1) (types VI1) (equivs VI1) (fun (const t1)) a1
        in b1
 
-    VType -> VGlueTy a0 phi (fun \is1 -> u @@ VI1 @@ is1)
-                            (fun \i -> mapVSystem makeEquiv (u @@ inot i @@ VItIsOne))
+    VType -> VGlueTy a0 phi (fun' "is1" \is1 -> u @@ VI1 @@ is1)
+                            (fun' "is1" \_ -> mapVSystem makeEquiv (u @@ VVar (Bound (T.pack "_equivLine_") (negate 3)) @@ VItIsOne))
 
+    VNe (HData False _) Seq.Empty -> a0
     VNe (HData False _) args ->
       case force a0 of
         VNe (HCon con_type con_name) con_args ->
@@ -301,6 +306,9 @@ comp a psi@phi u incA0@(compOutS (a @@ VI1) phi (u @@ VI1 @@ VItIsOne) -> a0) =
     
     VNe (HData True _) args -> compHIT (length args) (a @@) phi u incA0
 
+    VLam{} -> error $ "comp VLam " ++ show (prettyTm (quote a))
+    sys@VSystem{} -> error $ "comp VSystem: " ++ show (prettyTm (quote sys))
+
     _ -> VComp a phi u (VInc (a @@ VI0) phi a0)
 
 mapVSystem :: (Value -> Value) -> Value -> Value
@@ -349,16 +357,16 @@ compConArgs total_args fam = go total_args where
 
   smuggle x = VNe (HData False (Bound "__comp_con_tyarg" (negate 10))) (Seq.singleton (PApp P.Ex x))
 
-compOutS :: NFSort -> NFEndp -> Value -> Value -> Value
+compOutS :: HasCallStack => NFSort -> NFEndp -> Value -> Value -> Value
 compOutS a b c d = compOutS a b c (force d) where
-  compOutS _ _hi _0 vl@VComp{}    = vl
+  compOutS _ _hi _0 vl@VComp{}   = vl
   compOutS _ _hi _0 (VInc _ _ x) = x
   compOutS a phi a0 v = outS a phi a0 v
 
 system :: (Value -> Value -> Value) -> Value
 system k = VLam P.Ex $ Closure (Bound "i" 0) \i -> VLam P.Ex $ Closure (Bound "phi" 0) \isone -> k i isone
 
-fill :: NFLine -> NFEndp -> Value -> Value -> NFEndp -> Value
+fill :: HasCallStack => NFLine -> NFEndp -> Value -> Value -> NFEndp -> Value
 fill a phi u a0 j =
   comp (line \i -> a @@ (i `iand` j))
        (phi `ior` inot j)
@@ -377,7 +385,7 @@ glueElem :: NFSort -> NFEndp -> NFPartial -> NFPartial -> NFPartial -> Value ->
 glueElem _a (force -> VI1) _tys _eqvs t _vl = t @@ VItIsOne
 glueElem a phi tys eqvs t vl = VGlue a phi tys eqvs t vl
 
-unglue   :: NFSort -> NFEndp -> NFPartial -> NFPartial -> Value -> Value
+unglue   :: HasCallStack => NFSort -> NFEndp -> NFPartial -> NFPartial -> Value -> Value
 unglue _a (force -> VI1) _tys eqvs x = vProj1 (eqvs @@ VItIsOne) @@ x
 unglue _a _phi _tys _eqvs (force -> VGlue _ _ _ _ _ vl) = vl
 unglue a phi tys eqvs (force -> VSystem fs) = VSystem (fmap (unglue a phi tys eqvs) fs)
@@ -434,21 +442,22 @@ contr a aC phi u =
   comp (line (const a))
     phi
     (system \i is1 -> ielim (line (const a)) (vProj1 aC) (u is1) (vProj2 aC @@ u is1) i)
-    (vProj1 aC)
+    (VInc a phi (vProj1 aC))
 
 transp :: (NFEndp -> Value) -> Value -> Value
 transp line a0 = comp (fun line) VI0 (system \_ _ -> VSystem mempty) (VInc (line VI0) VI0 a0)
 
 makeEquiv :: Value -> Value
-makeEquiv line = VPair f $ fun \y -> VPair (fib y) (fun \u -> p (vProj1 u) (vProj2 u) y)
+makeEquiv argh = VPair f $ fun \y -> VPair (fib y) (fun \u -> p (vProj1 u) (vProj2 u) y)
   where
+    line = fun \i -> substitute (Map.singleton (Bound (T.pack "_equivLine_") (negate 3)) (inot i)) argh
     a = line @@ VI0
     b = line @@ VI1
 
     f = fun \x -> transp (line @@) x
     g = fun \x -> transp ((line @@) . inot) x
-    u i = fun \x -> fill line VI0 (system \_ _ -> mkVSystem mempty) x i
-    v i = fun \x -> fill (fun ((line @@) . inot)) VI0 (system \_ _ -> mkVSystem mempty) x i
+    u i = fun \x -> fill line VI0 (system \_ _ -> mkVSystem mempty) (VInc a VI0 x) i
+    v i = fun \x -> fill (fun ((line @@) . inot)) VI0 (system \_ _ -> mkVSystem mempty) (VInc a VI1 x) (inot i)
 
     fib y = VPair (g @@ y) (VLine b y (f @@ (g @@ y)) (fun (theta0 y VI1)))
     theta0 y i j = fill line (ior j (inot j)) (system \i _ -> mkVSystem (Map.fromList [(j, v i @@ y), (inot j, u i @@ (g @@ y))])) (VInc a (ior j (inot j)) (g @@ y)) i
diff --git a/src/Elab/WiredIn.hs-boot b/src/Elab/WiredIn.hs-boot
index 57cbe52..756cbc3 100644
--- a/src/Elab/WiredIn.hs-boot
+++ b/src/Elab/WiredIn.hs-boot
@@ -12,13 +12,13 @@ inot      :: NFEndp -> NFEndp
 ielim     :: NFSort -> Value -> Value -> Value -> NFEndp -> Value
 
 outS :: HasCallStack => NFSort -> NFEndp -> Value -> Value -> Value
-comp :: NFLine -> NFEndp -> Value -> Value -> Value
-fill :: NFLine -> NFEndp -> Value -> Value -> Value -> Value
+comp :: HasCallStack => NFLine -> NFEndp -> Value -> Value -> Value
+fill :: HasCallStack => NFLine -> NFEndp -> Value -> Value -> Value -> Value
 hComp :: NFSort -> NFEndp -> Value -> Value -> Value
 
 glueType :: NFSort -> NFEndp -> NFPartial -> NFPartial -> Value
 glueElem :: NFSort -> NFEndp -> NFPartial -> NFPartial -> NFPartial -> Value -> Value
-unglue   :: NFSort -> NFEndp -> NFPartial -> NFPartial -> Value -> Value
+unglue   :: HasCallStack => NFSort -> NFEndp -> NFPartial -> NFPartial -> Value -> Value
 
 fun :: (Value -> Value) -> Value
 system :: (Value -> Value -> Value) -> Value
\ No newline at end of file
diff --git a/src/Main.hs b/src/Main.hs
index 26ef83d..37e2871 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -53,7 +53,7 @@ main = do
     Check files verbose -> do
       env <- checkFiles files
       when verbose $ dumpEnv env
-    Repl -> enterReplIn =<< checkFiles ["./intro.tt"]
+    Repl -> enterReplIn =<< checkFiles ["./test.tt"]
 
 enterReplIn :: ElabEnv -> IO ()
 enterReplIn env = runInputT defaultSettings (loop env') where
diff --git a/src/Syntax.hs b/src/Syntax.hs
index fc23d66..1b8d56c 100644
--- a/src/Syntax.hs
+++ b/src/Syntax.hs
@@ -176,7 +176,7 @@ data Value
   | VGlue   NFSort NFEndp NFPartial NFPartial NFPartial Value
   | VUnglue NFSort NFEndp NFPartial NFPartial Value
 
-  | VCase Value Value [(Term, Term)]
+  | VCase (Map.Map Name (NFType, Value)) Value Value [(Term, Term)]
   deriving (Eq, Show, Ord)
 
 pattern VVar :: Name -> Value
@@ -256,7 +256,7 @@ quoteWith names (VGlueTy a phi t e)    = GlueTy (quoteWith names a) (quoteWith n
 quoteWith names (VGlue a phi ty e t x) = Glue (quoteWith names a) (quoteWith names phi) (quoteWith names ty) (quoteWith names e) (quoteWith names t) (quoteWith names x)
 quoteWith names (VUnglue a phi ty e x) = Unglue (quoteWith names a) (quoteWith names phi) (quoteWith names ty) (quoteWith names e) (quoteWith names x)
 
-quoteWith names (VCase rng v xs) = Case (quoteWith names rng) (quoteWith names v) xs
+quoteWith names (VCase _ rng v xs) = Case (quoteWith names rng) (quoteWith names v) xs
 
 alwaysShort :: Value -> Bool
 alwaysShort (VNe HCon{} _) = True
diff --git a/src/Syntax/Pretty.hs b/src/Syntax/Pretty.hs
index 7accd4c..546b3cf 100644
--- a/src/Syntax/Pretty.hs
+++ b/src/Syntax/Pretty.hs
@@ -114,8 +114,6 @@ prettyTm = prettyTm . everywhere (mkT beautify) where
   beautify (Inc _ _ u)       = toFun "inS" [u]
   beautify (Ouc a phi u u0)  = toFun "outS" [a, phi, u, u0]
 
-
-
   beautify (GlueTy a I1 _ _)    = a
   beautify (GlueTy a b c d)     = toFun "Glue"   [a,b,c,d]
   beautify (Glue a b c d e f)   = toFun "glue"   [a,b,c,d,e,f]