fixed bug where bound variable didn't exist in case

src/Renamer/Renamer.hs

@@ -3,16 +3,20 @@
 module Renamer.Renamer where
 
 import Auxiliary (mapAccumM)
-import           Control.Monad.State (MonadState, State, evalState, gets,
+import Control.Monad.State (
-                                      modify)
+    MonadState,
+    State,
+    evalState,
+    gets,
+    modify,
+ )
 import Data.List (foldl')
 import Data.Map (Map)
-import qualified Data.Map            as Map
+import Data.Map qualified as Map
 import Data.Maybe (fromMaybe)
 import Data.Tuple.Extra (dupe)
 import Grammar.Abs
 
-
 -- | Rename all variables and local binds
 rename :: Program -> Program
 rename (Program bs) = Program $ evalState (runRn $ mapM (renameSc initNames) bs) 0
@@ -28,9 +32,8 @@ rename (Program bs) = Program $ evalState (runRn $ mapM (renameSc initNames) bs)
         pure . DBind $ Bind name t name parms' rhs'
     renameSc _ def = pure def
 
-
 -- | Rename monad. State holds the number of renamed names.
-newtype Rn a = Rn { runRn :: State Int a }
+newtype Rn a = Rn {runRn :: State Int a}
     deriving (Functor, Applicative, Monad, MonadState Int)
 
 -- | Maps old to new name
@@ -46,36 +49,40 @@ renameLocalBind old_names (Bind name t _ parms rhs) = do
 renameExp :: Names -> Exp -> Rn (Names, Exp)
 renameExp old_names = \case
     EId n -> pure (old_names, EId . fromMaybe n $ Map.lookup n old_names)
-
     ELit (LInt i1) -> pure (old_names, ELit (LInt i1))
-
     EApp e1 e2 -> do
         (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 i e1 e2 -> do
         (new_names, e1') <- renameExp old_names e1
         (new_names', e2') <- renameExp new_names e2
         pure (new_names', ELet i e1' e2')
-
     EAbs par e -> do
         (new_names, par') <- newName old_names par
         (new_names', e') <- renameExp new_names e
         pure (new_names', EAbs par' e')
-
     EAnn e t -> do
         (new_names, e') <- renameExp old_names e
         pure (new_names, EAnn e' t)
-
     ECase e injs -> do
-        (new_names, e') <- renameExp old_names e
+        (_, e') <- renameExp old_names e
-        pure (new_names, ECase e' injs)
+        (new_names, injs') <- renameInjs old_names injs
+        pure (new_names, ECase e' injs')
+
+renameInjs :: Names -> [Inj] -> Rn (Names, [Inj])
+renameInjs ns xs = do
+    (new_names, xs') <- unzip <$> mapM (renameInj ns) xs
+    if null new_names then return (mempty, xs') else return (head new_names, xs')
+
+renameInj :: Names -> Inj -> Rn (Names, Inj)
+renameInj ns (Inj init e) = do
+    (new_names, e') <- renameExp ns e
+    return (new_names, Inj init e')
 
 -- | Create a new name and add it to name environment.
 newName :: Names -> Ident -> Rn (Names, Ident)

src/TypeChecker/TypeChecker.hs

@@ -1,9 +1,7 @@
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
+
 {-# HLINT ignore "Use mapAndUnzipM" #-}
-{-# OPTIONS_GHC -Wno-overlapping-patterns #-}
-{-# OPTIONS_GHC -Wno-unrecognised-pragmas #-}
-{-# OPTIONS_GHC -Wno-unused-matches #-}
 
 -- | A module for type checking and inference using algorithm W, Hindley-Milner
 module TypeChecker.TypeChecker where
@@ -73,9 +71,7 @@ freshenData (Data (Constr name ts) constrs) = do
 
 checkData :: Data -> Infer ()
 checkData d = do
-    trace ("OLD: " ++ show d) return ()
     d' <- freshenData d
-    trace ("NEW: " ++ show d') return ()
     case d' of
         (Data typ@(Constr name ts) constrs) -> do
             unless
@@ -249,7 +245,11 @@ algoW = \case
             -- applySt s2 $ do
             s3 <- unify (apply s2 t0) (TMono "Int")
             s4 <- unify (apply s3 t1) (TMono "Int")
-            return (s4 `compose` s3 `compose` s2 `compose` s1, TMono "Int", T.EAdd (TMono "Int") e0' e1')
+            return
+                ( s4 `compose` s3 `compose` s2 `compose` s1
+                , TMono "Int"
+                , T.EAdd (TMono "Int") e0' e1'
+                )
 
     -- \| Γ ⊢ e₀ : τ₀, S₀    S₀Γ ⊢ e₁ : τ₁, S1
     -- \| τ' = newvar    S₂ = mgu(S₁τ₀, τ₁ → τ')
@@ -280,7 +280,7 @@ algoW = \case
             (s2, t2, e1') <- algoW e1
             return (s2 `compose` s1, t2, T.ELet (T.Bind (name, t2) e0') e1')
     ECase caseExpr injs -> do
-        (s0, t0, e0') <- algoW caseExpr
+        (_, t0, e0') <- algoW caseExpr
         (injs', ts) <- unzip <$> mapM (checkInj t0) injs
         case ts of
             [] -> throwError "Case expression missing any matches"
@@ -292,14 +292,15 @@ algoW = \case
 
 -- | Unify two types producing a new substitution
 unify :: Type -> Type -> Infer Subst
-unify t0 t1 = case (trace ("LEFT: " ++ show t0) t0, trace ("RIGHT: " ++ show t1) t1) of
+unify t0 t1 = case (t0, t1) of
     (TArr a b, TArr c d) -> do
         s1 <- unify a c
         s2 <- unify (apply s1 b) (apply s1 d)
         return $ s1 `compose` s2
     (TPol a, b) -> occurs a b
     (a, TPol b) -> occurs b a
-    (TMono a, TMono b) -> if a == b then return M.empty else throwError "Types do not unify"
+    (TMono a, TMono b) ->
+        if a == b then return M.empty else throwError "Types do not unify"
     -- \| TODO: Figure out a cleaner way to express the same thing
     (TConstr (Constr name t), TConstr (Constr name' t')) ->
         if name == name' && length t == length t'
@@ -316,10 +317,17 @@ unify t0 t1 = case (trace ("LEFT: " ++ show t0) t0, trace ("RIGHT: " ++ show t1)
                         , printTree name'
                         , "(" ++ printTree t' ++ ")"
                         ]
-    (a, b) -> throwError . unwords $ ["Type:", printTree a, "can't be unified with:", printTree b]
+    (a, b) ->
+        throwError . unwords $
+            [ "Type:"
+            , printTree a
+            , "can't be unified with:"
+            , printTree b
+            ]
 
 {- | Check if a type is contained in another type.
-I.E. { a = a -> b } is an unsolvable constraint since there is no substitution such that these are equal
+I.E. { a = a -> b } is an unsolvable constraint since there is no substitution
+such that these are equal
 -}
 occurs :: Ident -> Type -> Infer Subst
 occurs _ (TPol _) = return nullSubst
@@ -339,7 +347,9 @@ occurs i t =
 generalize :: Map Ident Poly -> Type -> Poly
 generalize env t = Forall (S.toList $ free t S.\\ free env) t
 
--- | Instantiate a polymorphic type. The free type variables are substituted with fresh ones.
+{- | Instantiate a polymorphic type. The free type variables are substituted
+with fresh ones.
+-}
 inst :: Poly -> Infer Type
 inst (Forall xs t) = do
     xs' <- mapM (const fresh) xs
@@ -364,7 +374,8 @@ instance FreeVars Type where
     free (TMono _) = mempty
     free (TArr a b) = free a `S.union` free b
     -- \| Not guaranteed to be correct
-    free (TConstr (Constr _ a)) = foldl' (\acc x -> free x `S.union` acc) S.empty a
+    free (TConstr (Constr _ a)) =
+        foldl' (\acc x -> free x `S.union` acc) S.empty a
 
     apply :: Subst -> Type -> Type
     apply sub t = do
@@ -413,7 +424,8 @@ insertSig i t = modify (\st -> st {sigs = M.insert i t (sigs st)})
 
 -- | Insert a constructor with its data type
 insertConstr :: Ident -> Type -> Infer ()
-insertConstr i t = modify (\st -> st {constructors = M.insert i t (constructors st)})
+insertConstr i t =
+    modify (\st -> st {constructors = M.insert i t (constructors st)})
 
 -------- PATTERN MATCHING ---------
 
@@ -421,7 +433,7 @@ insertConstr i t = modify (\st -> st {constructors = M.insert i t (constructors
 checkInj :: Type -> Inj -> Infer (T.Inj, Type)
 checkInj caseType (Inj it expr) = do
     (args, t') <- initType caseType it
-    (s, t, e') <- local (\st -> st {vars = args}) (algoW expr)
+    (_, t, e') <- local (\st -> st {vars = args `M.union` vars st}) (algoW expr)
     return (T.Inj (it, t') e', t)
 
 initType :: Type -> Init -> Infer (Map Ident Poly, Type)
@@ -469,4 +481,4 @@ flattenType (TArr a b) = flattenType a ++ flattenType b
 flattenType a = [a]
 
 litType :: Literal -> Type
-litType (LInt i) = TMono "Int"
+litType (LInt _) = TMono "Int"

test_program

@@ -13,11 +13,11 @@ data Maybe ('a) where {
     Just : 'a -> Maybe ('a)
 };
 
-id : 'a -> 'a ;
+-- id : 'a -> 'a ;
-id x = x ;
+-- id x = x ;
 
-main : Maybe ('a -> 'a) ;
+-- main : Maybe ('a -> 'a) ;
-main = Just id;
+-- main = Just id;
 
 -- data Either ('a 'b) where {
 --     Left : 'a -> Either ('a 'b)
@@ -40,11 +40,11 @@ main = Just id;
 --         Left y => Nothing ;
 --         Right x => Just x
 --     };
--- 
+ 
--- -- Bug. f not included in the case-expression context
+-- Bug. f not included in the case-expression context
--- fmap : ('a -> 'b) -> Maybe ('a) -> Maybe ('b) ;
+fmap : ('a -> 'b) -> Maybe ('a) -> Maybe ('b) ;
--- fmap f x =
+fmap f x =
---     case x of {
+    case x of {
---         Just x => Just (f x) ;
+        Just x => Just (f x) ;
---         Nothing => Nothing
+        Nothing => Nothing
---     }
+    }