Change grammar: only one bind in let and no EAnn for typed syntax

Grammar.cf

@@ -1,19 +1,15 @@
 Program. Program ::= [Bind];
 
-
 EId.  Exp3 ::= Ident;
 EInt. Exp3 ::= Integer;
-ELet.  Exp3 ::= "let" [Bind] "in" Exp; 
+EAnn. Exp3  ::= "(" Exp ":" Type ")";
+ELet. Exp3 ::= "let" Bind "in" Exp; 
 EApp. Exp2 ::= Exp2 Exp3;
 EAdd. Exp1 ::= Exp1 "+" Exp2;
 EAbs. Exp  ::= "\\" Ident ":" Type "." Exp;
-EAnn.  Exp3 ::= "(" Exp ":" Type ")";
-
 ECase. Exp ::= "case" Exp "of" "{" [CaseMatch] "}";
--- 
 CaseMatch. CaseMatch ::= Case "=>" Exp ;
 separator CaseMatch ",";
---terminator CaseMatch ".";
 
 CInt. Case ::= Integer ;
 

sample-programs/basic-1

@@ -3,18 +3,19 @@
 -- tripplemagic x y z = ((\x:Int. x+x) x) + y + z;
 -- main : Int;
 -- main = tripplemagic ((\x:Int. x+x+3) ((\x:Int. x) 2)) 5 3
+-- answer: 22
 
 -- apply : (Int -> Int) -> Int -> Int;
 -- apply f x = f x;
---
 -- main : Int;
---main = (\x : Int . x + 5) 5
+-- main = apply (\x : Int . x + 5) 5
-
+-- answer: 10
 
 apply : (Int -> Int -> Int) -> Int -> Int -> Int;
 apply f x y = f x y;
 krimp: Int -> Int -> Int;
 krimp x y = x + y;
 main : Int;
-main = apply (krimp) 2 3;--apply (\y: Int . (\x: Int . x + y + 2)) 5 2;
+main = apply (krimp) 2 3;
+-- answer: 5
 

src/Compiler.hs

@@ -9,13 +9,9 @@ import qualified Data.Map as Map
 import           Data.Tuple.Extra    (second)
 import           Grammar.ErrM        (Err)
 import           Grammar.Print       (printTree)
-import LlvmIr (
+import           LlvmIr              (LLVMIr (..), LLVMType (..),
-    LLVMIr (..),
+                                      LLVMValue (..), Visibility (..),
-    LLVMType (..),
+                                      llvmIrToString)
-    LLVMValue (..),
-    Visibility (..),
-    llvmIrToString,
- )
 import           TypeChecker         (partitionType)
 import           TypeCheckerIr
 
@@ -129,28 +125,24 @@ compile (Program prg) = do
     go (EId (name, _)) = emitIdent name
     go (EApp t e1 e2)  = emitApp t e1 e2
     go (EAbs t ti e)   = emitAbs t ti e
-    go (ELet binds e) = emitLet binds e
+    go (ELet bind e)   = emitLet bind e
-    go (EAnn _ _) = emitEAnn
     -- go (ESub e1 e2)  = emitSub e1 e2
     -- go (EMul e1 e2)  = emitMul e1 e2
     -- go (EDiv e1 e2)  = emitDiv e1 e2
     -- go (EMod e1 e2)  = emitMod e1 e2
 
     --- aux functions ---
-    emitEAnn :: CompilerState ()
-    emitEAnn = emit . UnsafeRaw $ "why?"
-
     emitAbs :: Type -> Id -> Exp -> CompilerState ()
     emitAbs _t tid e = do
         emit . Comment $
             "Lambda escaped previous stages: \\" <> show tid <> " . " <> show e
-    emitLet :: [Bind] -> Exp -> CompilerState ()
+    emitLet :: Bind -> Exp -> CompilerState ()
-    emitLet xs e = do
+    emitLet b e = do
         emit $
             Comment $
                 concat
                     [ "ELet ("
-                    , show xs
+                    , show b
                     , " = "
                     , show e
                     , ") is not implemented!"
@@ -280,7 +272,6 @@ getType (EId (_, t)) = type2LlvmType t
 getType (EApp t _ _) = type2LlvmType t
 getType (EAbs t _ _) = type2LlvmType t
 getType (ELet _ e)   = getType e
-getType (EAnn _ t) = type2LlvmType t
 
 valueGetType :: LLVMValue -> LLVMType
 valueGetType (VInteger _)      = I64

src/LambdaLifter.hs

@@ -7,12 +7,10 @@ module LambdaLifter (lambdaLift, freeVars, abstract, rename, collectScs) where
 import           Auxiliary           (snoc)
 import           Control.Applicative (Applicative (liftA2))
 import           Control.Monad.State (MonadState (get, put), State, evalState)
-import           Data.Foldable.Extra (notNull)
+import           Data.Set            (Set)
-import           Data.List           (mapAccumL, partition)
-import           Data.Set            (Set, (\\))
 import qualified Data.Set            as Set
 import           Prelude             hiding (exp)
-import           Renamer             hiding (fromBinders)
+import           Renamer
 import           TypeCheckerIr
 
 
@@ -49,35 +47,22 @@ freeVarsExp localVars = \case
     where
       e' = freeVarsExp (Set.insert par localVars) e
 
-  -- Sum free variables present in binders and the expression
+  -- Sum free variables present in bind and the expression
-  ELet binders e  -> (Set.union binders_frees e_free, ALet binders' e')
+  ELet (Bind name parms rhs) e  -> (Set.union binders_frees e_free, ALet new_bind e')
     where
-      binders_frees = rhss_frees \\ names_set
+      binders_frees = Set.delete name $ freeVarsOf rhs'
-      e_free        = freeVarsOf e' \\ names_set
+      e_free        = Set.delete name $ freeVarsOf e'
 
-      rhss_frees = foldr1 Set.union (map freeVarsOf rhss')
+      rhs'     = freeVarsExp e_localVars rhs
-      names_set  = Set.fromList names
+      new_bind = ABind name parms rhs'
 
-      (names, parms, rhss) = fromBinders binders
-      rhss'                = map (freeVarsExp e_localVars) rhss
-      e_localVars          = Set.union localVars names_set
-
-      binders' = zipWith3 ABind names parms rhss'
       e'          = freeVarsExp e_localVars e
-
+      e_localVars = Set.insert name localVars
-  EAnn e t -> (freeVarsOf e', AAnn e' t)
-    where
-      e' = freeVarsExp localVars e
 
 
 freeVarsOf :: AnnExp -> Set Id
 freeVarsOf = fst
 
-
-fromBinders :: [Bind] -> ([Id], [[Id]], [Exp])
-fromBinders bs = unzip3 [ (name, parms, rhs) | Bind name parms rhs <- bs ]
-
-
 -- AST annotated with free variables
 type AnnProgram = [(Id, [Id], AnnExp)]
 
@@ -87,14 +72,11 @@ data ABind = ABind Id [Id] AnnExp deriving Show
 
 data AnnExp' = AId  Id
              | AInt Integer
-             | ALet [ABind] AnnExp
+             | ALet ABind AnnExp
              | AApp Type    AnnExp  AnnExp
              | AAdd Type    AnnExp  AnnExp
              | AAbs Type    Id      AnnExp
-             | AAnn AnnExp  Type
              deriving Show
-
-
 -- | Lift lambdas to let expression of the form @let sc = \v₁ x₁ -> e₁@.
 -- Free variables are @v₁ v₂ .. vₙ@ are bound.
 abstract :: AnnProgram -> Program
@@ -124,7 +106,7 @@ abstractExp (free, exp) = case exp of
   AInt i       -> pure $ EInt i
   AApp t e1 e2 -> liftA2 (EApp t) (abstractExp e1) (abstractExp e2)
   AAdd t e1 e2 -> liftA2 (EAdd t) (abstractExp e1) (abstractExp e2)
-  ALet bs e    -> liftA2 ELet (mapM go bs) (abstractExp e)
+  ALet b e     -> liftA2 ELet (go b) (abstractExp e)
     where
       go (ABind name parms rhs) = do
           (rhs', parms1)  <- flattenLambdas <$> skipLambdas abstractExp rhs
@@ -141,14 +123,13 @@ abstractExp (free, exp) = case exp of
     rhs <- abstractExp e
 
     let sc_name = Ident ("sc_" ++ show i)
-        sc      = ELet [Bind (sc_name, t) parms rhs] $ EId (sc_name, t)
+        sc      = ELet (Bind (sc_name, t) parms rhs) $ EId (sc_name, t)
 
     pure $ foldl (EApp TInt) sc $ map EId freeList
     where
       freeList = Set.toList free
       parms    = snoc parm freeList
 
-  AAnn e t -> abstractExp e >>= \e' -> pure $ EAnn e' t
 
 nextNumber :: State Int Int
 nextNumber = do
@@ -156,7 +137,7 @@ nextNumber = do
   put $ succ i
   pure i
 
--- | Collects supercombinators by lifting appropriate let expressions
+-- | Collects supercombinators by lifting non-constant let expressions
 collectScs :: Program -> Program
 collectScs (Program scs) = Program $ concatMap collectFromRhs scs
   where
@@ -184,32 +165,18 @@ collectScsExp = \case
       where
         (scs, e') = collectScsExp e
 
-  -- Collect supercombinators from binds, the rhss, and the expression.
+    -- Collect supercombinators from bind, the rhss, and the expression.
     --
-  -- > f = let
+    -- > f = let sc x y = rhs in e
-  -- >       sc  = rhs
-  -- >       sc1 = rhs1
-  -- >          ...
-  -- >     in e
     --
-  ELet binds e -> (binds_scs ++ rhss_scs ++ e_scs, mkEAbs non_scs' e')
+    ELet (Bind name parms rhs) e -> if null parms
+                                    then (       rhs_scs ++ e_scs, ELet bind e')
+                                    else (bind : rhs_scs ++ e_scs, e')
       where
-      binds_scs          = [ let (rhs', parms1) = flattenLambdas rhs in
+        bind            = Bind name parms rhs'
-                             Bind n (parms ++ parms1) rhs'
+        (rhs_scs, rhs') = collectScsExp rhs
-                           | Bind n parms rhs <- scs'
-                           ]
-      (rhss_scs, binds') = mapAccumL collectScsRhs [] binds
         (e_scs, e')     = collectScsExp e
 
-      (scs', non_scs') = partition (\(Bind _ pars _) -> notNull pars) binds'
-
-      collectScsRhs acc (Bind n xs rhs) = (acc ++ rhs_scs, Bind n xs rhs')
-        where
-          (rhs_scs, rhs') = collectScsExp rhs
-
-  EAnn e t -> (scs, EAnn e' t)
-    where
-      (scs, e') = collectScsExp e
 
 -- @\x.\y.\z. e → (e, [x,y,z])@
 flattenLambdas :: Exp -> (Exp, [Id])
@@ -218,7 +185,3 @@ flattenLambdas = go . (, [])
     go (e, acc) = case e of
                    EAbs _ par e1 -> go (e1, snoc par acc)
                    _             -> (e, acc)
-
-mkEAbs :: [Bind] -> Exp -> Exp
-mkEAbs [] e = e
-mkEAbs bs e = ELet bs e

src/Renamer.hs

@@ -2,82 +2,84 @@
 
 module Renamer (module Renamer) where
 
-import           Data.List   (mapAccumL, unzip4, zipWith4)
+import           Auxiliary           (mapAccumM)
+import           Control.Monad.State (MonadState, State, evalState, gets,
+                                      modify)
 import           Data.Map            (Map)
 import qualified Data.Map            as Map
 import           Data.Maybe          (fromMaybe)
+import           Data.Tuple.Extra    (dupe)
 import           Grammar.Abs
 
 
--- | Rename all supercombinators and variables
+-- | Rename all variables and local binds
 rename :: Program -> Program
-rename (Program sc) = Program $ map (renameSc 0) sc
+rename (Program bs) = Program $ evalState (runRn $ mapM (renameSc initNames) bs) 0
   where
-    renameSc i (Bind n t _ xs e) = Bind n t n xs' e'
+    initNames = Map.fromList $ map (\(Bind name _ _ _ _) -> dupe name) bs
-      where
+    renameSc :: Names -> Bind -> Rn Bind
-        (i1, xs', env) = newNames i xs
+    renameSc old_names (Bind name t _ parms rhs) = do
-        e'             = snd $ renameExp env i1 e
+        (new_names, parms') <- newNames old_names parms
-
+        rhs'                <- snd <$> renameExp new_names rhs
-renameExp :: Map Ident Ident -> Int -> Exp -> (Int, Exp)
+        pure $ Bind name t name parms' rhs'
-renameExp env i = \case
-
-  EId  n     -> (i, EId . fromMaybe n $ Map.lookup n env)
-
-  EInt i1    -> (i, EInt i1)
-
-  EApp e1 e2 -> (i2, EApp e1' e2')
-    where
-      (i1, e1') = renameExp env i e1
-      (i2, e2') = renameExp env i1 e2
-
-  EAdd e1 e2 -> (i2, EAdd e1' e2')
-    where
-      (i1, e1') = renameExp env i e1
-      (i2, e2') = renameExp env i1 e2
-
-  ELet bs e  -> (i3, ELet (zipWith4 mkBind names' types pars' es') e')
-    where
-      mkBind name t              = Bind name t name
-      (i1, e')                   = renameExp e_env i e
-      (names, types, pars, rhss) = fromBinders bs
-      (i2, names', env')         = newNames i1 (names ++ concat pars)
-      pars'                      = (map . map) renamePar pars
-      e_env                      = Map.union env' env
-      (i3, es')                  = mapAccumL (renameExp e_env) i2 rhss
-
-      renamePar p = case Map.lookup p env' of
-                     Just p' -> p'
-                     Nothing -> error ("Can't find name for " ++ show p)
 
 
-  EAbs par t e  -> (i2, EAbs par' t e')
+-- | Rename monad. State holds the number of renamed names.
-    where
+newtype Rn a = Rn { runRn :: State Int a }
-      (i1, par', env') = newName par
+  deriving (Functor, Applicative, Monad, MonadState Int)
-      (i2, e')         = renameExp (Map.union env' env ) i1 e
 
-  EAnn e t -> (i1, EAnn e' t)
+-- | Maps old to new name
-    where
+type Names = Map Ident Ident
-      (i1, e') = renameExp env i e
 
+renameLocalBind :: Names -> Bind -> Rn (Names, Bind)
+renameLocalBind old_names (Bind name t _ parms rhs) = do
+    (new_names, name')   <- newName old_names name
+    (new_names', parms') <- newNames new_names parms
+    (new_names'', rhs')  <- renameExp new_names' rhs
+    pure (new_names'', Bind name' t name' parms' rhs')
 
-newName :: Ident -> (Int, Ident, Map Ident Ident)
+renameExp :: Names -> Exp -> Rn (Names, Exp)
-newName old_name = (i, head names, env)
+renameExp old_names = \case
-  where (i, names, env) = newNames 1 [old_name]
 
-newNames :: Int -> [Ident] -> (Int, [Ident], Map Ident Ident)
+  EId  n     -> pure (old_names, EId . fromMaybe n $ Map.lookup n old_names)
-newNames i old_names = (i', new_names, env)
-  where
-    (i', new_names) = getNames i old_names
-    env = Map.fromList $ zip old_names new_names
 
-getNames :: Int -> [Ident] -> (Int, [Ident])
+  EInt i1    -> pure (old_names, EInt i1)
-getNames i ns = (i + length ss, zipWith makeName ss [i..])
-  where
-    ss = map (\(Ident s) -> s) ns
 
-makeName :: String -> Int -> Ident
+  EApp e1 e2 -> do
-makeName prefix i = Ident (prefix ++ "_" ++ show i)
+      (env1, e1') <- renameExp old_names e1
+      (env2, e2') <- renameExp old_names e2
+      pure (Map.union env1 env2, EApp e1' e2')
 
+  EAdd e1 e2 -> do
+      (env1, e1') <- renameExp old_names e1
+      (env2, e2') <- renameExp old_names e2
+      pure (Map.union env1 env2, EAdd e1' e2')
+
+  ELet b e  -> do
+      (new_names, b)  <- renameLocalBind old_names b
+      (new_names', e') <- renameExp new_names e
+      pure (new_names', ELet b e')
+
+  EAbs par t e  -> do
+      (new_names, par') <- newName old_names par
+      (new_names', e')  <- renameExp new_names e
+      pure (new_names', EAbs par' t e')
+
+  EAnn e t -> do
+      (new_names, e') <- renameExp old_names e
+      pure (new_names, EAnn e' t)
+
+-- | Create a new name and add it to name environment.
+newName :: Names -> Ident -> Rn (Names, Ident)
+newName env old_name = do
+    new_name <- makeName old_name
+    pure (Map.insert old_name new_name env, new_name)
+
+-- | Create multiple names and add them to the name environment
+newNames :: Names -> [Ident] -> Rn (Names, [Ident])
+newNames = mapAccumM newName
+
+-- | Annotate name with number and increment the number @prefix ⇒ prefix_number@.
+makeName :: Ident -> Rn Ident
+makeName (Ident prefix) = gets (\i -> Ident $ prefix ++ "_" ++ show i) <* modify succ
 
-fromBinders :: [Bind] -> ([Ident], [Type], [[Ident]], [Exp])
-fromBinders bs = unzip4 [ (name, t, parms, rhs) | Bind name t _ parms rhs <- bs ]

src/TypeChecker.hs

@@ -87,18 +87,17 @@ infer cxt = \case
     let t_abs = TFun t t1
     pure (T.EAbs t_abs (x, t) e', t_abs)
 
-  ELet bs e -> do
+  ELet b e -> do
-    bs''    <- mapM (checkBind cxt') bs'
+    let cxt' = insertBind b cxt
+    b'    <- checkBind cxt' b
     (e', t) <- infer cxt' e
-    pure (T.ELet bs'' e', t)
+    pure (T.ELet b' e', t)
-    where
-      bs'  = map expandLambdas bs
-      cxt' = foldr (\(Bind n t _ _ _) -> insertEnv n t) cxt bs'
 
   EAnn e t -> do
-    e' <- check cxt e t
+      (e', t1) <- infer cxt e
-    pure (T.EAnn e' t, t)
+      unless (typeEq t t1) $
-
+        throwError "Inferred type and type annotation doesn't match"
+      pure (e', t1)
 
 check :: Cxt -> Exp -> Type -> Err T.Exp
 check cxt exp typ = case exp of
@@ -137,19 +136,19 @@ check cxt exp typ = case exp of
     unless (typeEq t1 typ) $ throwError "Wrong lamda type!"
     pure $ T.EAbs t1 (x, t) e'
 
-  ELet bs e -> do
+  ELet b e -> do
-    bs'' <- mapM (checkBind cxt') bs'
+    let cxt' = insertBind b cxt
+    b' <- checkBind cxt' b
     e' <- check cxt' e typ
-    pure $ T.ELet bs'' e'
+    pure $ T.ELet b' e'
-    where
-      bs'  = map expandLambdas bs
-      cxt' = foldr (\(Bind n t _ _ _) -> insertEnv n t) cxt bs'
 
   EAnn e t -> do
     unless (typeEq t typ) $
       throwError "Inferred type and type annotation doesn't match"
-    e' <- check cxt e t
+    check cxt e t
-    pure $ T.EAnn e' typ
+
+insertBind :: Bind -> Cxt -> Cxt
+insertBind (Bind n t _ _ _) = insertEnv n t
 
 typeEq :: Type -> Type -> Bool
 typeEq (TFun t t1) (TFun q q1) = typeEq t q && typeEq t1 q1

src/TypeCheckerIr.hs

@@ -16,11 +16,10 @@ newtype Program = Program [Bind]
 data Exp
     = EId  Id
     | EInt Integer
-    | ELet [Bind] Exp
+    | ELet Bind Exp
     | EApp Type Exp Exp
     | EAdd Type Exp Exp
     | EAbs Type Id  Exp
-    | EAnn Exp Type
   deriving (C.Eq, C.Ord, C.Show, C.Read)
 
 type Id = (Ident, Type)
@@ -97,12 +96,5 @@ instance Print Exp where
                       , doc $ showString "."
                       , prt 0 e
                       ]
-    EAnn e t     -> prPrec i 3 $ concatD
-                      [ doc $ showString "("
-                      , prt 0 e
-                      , doc $ showString ":"
-                      , prt 0 t
-                      , doc $ showString ")"
-                      ]