diff --git a/gibbon-compiler/src/Gibbon/Compiler.hs b/gibbon-compiler/src/Gibbon/Compiler.hs
index 6c2e8290..7a26220f 100644
--- a/gibbon-compiler/src/Gibbon/Compiler.hs
+++ b/gibbon-compiler/src/Gibbon/Compiler.hs
@@ -838,13 +838,13 @@ Also see Note [Adding dummy traversals] and Note [Adding random access nodes].
       go :: PassRunner a b v
       go = pass config
 
-      goE2 :: (InterpProg Store b, Show v) => InterpPassRunner a b Store v
+      goE2 :: (InterpProg Store b Var, Show v) => InterpPassRunner a b Store v
       goE2 = passE emptyStore config
 
-      goE0 :: (InterpProg () b, Show v) => InterpPassRunner a b () v
+      goE0 :: (InterpProg () b Var, Show v) => InterpPassRunner a b () v
       goE0 = passE () config
 
-      goE1 :: (InterpProg () b, Show v) => InterpPassRunner a b () v
+      goE1 :: (InterpProg () b Var, Show v) => InterpPassRunner a b () v
       goE1 = passE () config
 
 type PassRunner a b v = (Pretty b, Out b, NFData a, NFData b) =>
@@ -852,7 +852,7 @@ type PassRunner a b v = (Pretty b, Out b, NFData a, NFData b) =>
 
 type InterpPassRunner a b s v = (HasPretty a, HasPretty b, HasOut a, HasOut b,
                                 HasGeneric a, HasGeneric b, HasNFData a, HasNFData b) =>
-                                String -> (Prog a -> PassM (Prog b)) -> Prog a -> StateT (CompileState v) IO (Prog b)
+                                String -> (Prog Var a -> PassM (Prog Var b)) -> Prog Var a -> StateT (CompileState v) IO (Prog Var b)
 
 -- | Run a pass and return the result
 --
@@ -882,7 +882,7 @@ passChatterLvl = 3
 
 -- | Like 'pass', but also evaluates and checks the result.
 --
-passE :: (InterpProg s p2, Show v) => s -> Config -> InterpPassRunner p1 p2 s v
+passE :: (InterpProg s p2 Var, Show v) => s -> Config -> InterpPassRunner p1 p2 s v
 passE s config@Config{mode} = wrapInterp s mode (pass config)
 
 
@@ -896,7 +896,7 @@ passF = pass
 
 -- | Wrapper to enable running a pass AND interpreting the result.
 --
-wrapInterp :: (InterpProg s b, Show v)
+wrapInterp :: (InterpProg s b Var, Show v)
            => s -> Mode -> InterpPassRunner a b s v -> InterpPassRunner a b s v
 wrapInterp s mode pass who fn x =
   do CompileState{result} <- get
diff --git a/gibbon-compiler/src/Gibbon/L0/Specialize2.hs b/gibbon-compiler/src/Gibbon/L0/Specialize2.hs
index 3bb8d693..103dd9b7 100644
--- a/gibbon-compiler/src/Gibbon/L0/Specialize2.hs
+++ b/gibbon-compiler/src/Gibbon/L0/Specialize2.hs
@@ -459,7 +459,7 @@ monoOblsTy ddefs1 t = do
 
 
 -- | Collect monomorphization obligations.
-collectMonoObls :: DDefs0 -> Env2 Ty0 -> S.Set Var -> Exp0 -> MonoM Exp0
+collectMonoObls :: DDefs0 -> Env2 Var Ty0 -> S.Set Var -> Exp0 -> MonoM Exp0
 collectMonoObls ddefs env2 toplevel ex =
   case ex of
     AppE f [] args -> do
@@ -998,7 +998,7 @@ specLambdasFun ddefs new_fn_name refs fn@FunDef{funArgs, funTy} = do
 
     subst' old new ex = gRename (M.singleton old new) ex
 
-specLambdasExp :: DDefs0 -> Env2 Ty0 -> Exp0 -> SpecM Exp0
+specLambdasExp :: DDefs0 -> Env2 Var Ty0 -> Exp0 -> SpecM Exp0
 specLambdasExp ddefs env2 ex =
   case ex of
     -- TODO, docs.
@@ -1204,7 +1204,7 @@ specLambdasExp ddefs env2 ex =
         _ -> False
 
     -- fn_0 (fn_1, thing, fn_2) => fn_0 (thing)
-    dropFunRefs :: Var -> Env2 Ty0 -> [Exp0] -> [Exp0]
+    dropFunRefs :: Var -> Env2 Var Ty0 -> [Exp0] -> [Exp0]
     dropFunRefs fn_name env21 args =
       foldr (\(a,t) acc -> if isFunTy t then acc else a:acc) [] (zip args arg_tys)
       where
@@ -1737,7 +1737,7 @@ floatOutCase (Prog ddefs fundefs mainExp) = do
   where
     err1 msg = error $ "floatOutCase: " ++ msg
 
-    float_fn :: Env2 Ty0 -> Exp0 -> FloatM Exp0
+    float_fn :: Env2 Var Ty0 -> Exp0 -> FloatM Exp0
     float_fn env2 ex = do
       fundefs' <- get
       let fenv' = M.map funTy fundefs'
@@ -1752,7 +1752,7 @@ floatOutCase (Prog ddefs fundefs mainExp) = do
       let fn = FunDef fn_name args fn_ty ex' (FunMeta NotRec NoInline False)
       state (\s -> ((AppE fn_name [] (map VarE free)), M.insert fn_name fn s))
 
-    go :: Bool -> Env2 Ty0 -> Exp0 -> FloatM Exp0
+    go :: Bool -> Env2 Var Ty0 -> Exp0 -> FloatM Exp0
     go float env2 ex =
       case ex of
         VarE{}    -> pure ex
diff --git a/gibbon-compiler/src/Gibbon/Passes/Flatten.hs b/gibbon-compiler/src/Gibbon/Passes/Flatten.hs
index 985c285c..5c205a19 100644
--- a/gibbon-compiler/src/Gibbon/Passes/Flatten.hs
+++ b/gibbon-compiler/src/Gibbon/Passes/Flatten.hs
@@ -45,8 +45,9 @@ flattenL1 prg@(Prog defs funs main) = do
 
     env20 = progToEnv prg
 
-
-flattenL2 :: Flattenable (E2Ext Var (UrTy LocVar)) => Prog2 -> PassM Prog2
+-- removing constraint solves compilation error 
+-- (Flattenable (E2Ext Var (UrTy LocVar)))
+flattenL2 :: Prog2 -> PassM Prog2
 flattenL2 prg@(Prog defs funs main) = do
     main' <-
       case main of
diff --git a/gibbon-compiler/src/Gibbon/Pretty.hs b/gibbon-compiler/src/Gibbon/Pretty.hs
index 44defae2..79ceab19 100644
--- a/gibbon-compiler/src/Gibbon/Pretty.hs
+++ b/gibbon-compiler/src/Gibbon/Pretty.hs
@@ -53,7 +53,7 @@ indentLevel = 4
 type HasPretty ex = (Pretty ex, Pretty (TyOf ex), Pretty (ArrowTy (TyOf ex)))
 
 -- Program:
-instance HasPretty ex => Pretty (Prog ex) where
+instance HasPretty ex => Pretty (Prog Var ex) where
     pprintWithStyle sty (Prog ddefs funs me) =
         let meDoc = case me of
                       Nothing -> empty
@@ -165,7 +165,7 @@ instance Pretty FunMeta where
     pprintWithStyle _sty = text . show
 
 -- Functions:
-instance HasPretty ex => Pretty (FunDef ex) where
+instance HasPretty ex => Pretty (FunDef Var ex) where
     pprintWithStyle sty FunDef{funName,funArgs,funTy,funBody,funMeta} =
         braces (text "meta:" <+> pprintWithStyle sty funMeta) $$
           text (fromVar funName) <+> doublecolon <+> pprintWithStyle sty funTy
@@ -482,6 +482,9 @@ instance HasPrettyToo E2Ext l d => Pretty (L2.E2Ext l d) where
           L2.SSPush mode loc endloc tycon -> text "ss_push" <+> doc mode <+> pprint loc <+> pprint endloc <+> doc tycon
           L2.SSPop mode loc endloc -> text "ss_pop" <+> doc mode <+> pprint loc <+> pprint endloc
 
+instance Pretty L2.LocVar where 
+  pprintWithStyle _ loc = parens $ text $ sdoc loc
+
 instance Pretty L2.Region where
   pprintWithStyle _ reg = parens $ text $ sdoc reg
 
@@ -647,7 +650,7 @@ pprintHsWithEnv p@Prog{ddefs,fundefs,mainExp} =
 
     sty = PPHaskell
 
-    ppFun :: Env2 Ty1 -> FunDef1 -> Doc
+    ppFun :: Env2 Var Ty1 -> FunDef1 -> Doc
     ppFun env2 FunDef{funName, funArgs, funTy, funBody} =
       text (fromVar funName) <+> doublecolon <+> pprintWithStyle sty funTy
              $$ renderBod <> text "\n"
@@ -657,7 +660,7 @@ pprintHsWithEnv p@Prog{ddefs,fundefs,mainExp} =
         renderBod = text (fromVar funName) <+> (hsep $ map (text . fromVar) funArgs) <+> equals
                       $$ nest indentLevel (ppExp False env2' funBody)
 
-    ppExp :: Bool -> Env2 Ty1 -> Exp1 -> Doc
+    ppExp :: Bool -> Env2 Var Ty1 -> Exp1 -> Doc
     ppExp monadic env2 ex0 =
       case ex0 of
           VarE v -> pprintWithStyle sty v
diff --git a/gibbon-compiler/src/Gibbon/SExpFrontend.hs b/gibbon-compiler/src/Gibbon/SExpFrontend.hs
index e9c42cdd..5edf4fa4 100644
--- a/gibbon-compiler/src/Gibbon/SExpFrontend.hs
+++ b/gibbon-compiler/src/Gibbon/SExpFrontend.hs
@@ -20,7 +20,7 @@ import qualified Data.List as L
 import Data.Loc ( Loc(..), Pos(..))
 import qualified Data.Map as M
 import qualified Data.Set as S
-import Data.Text hiding (map, head, init, last, length, zip, reverse, foldr)
+import Data.Text hiding (map, head, init, last, length, zip, reverse, foldr, show)
 import qualified Data.Text as T
 import Data.Text.IO (readFile)
 import System.FilePath