Destroy fancy typing, and some work

1 files changed, 186 insertions, 49 deletions

diff --git a/src/HSVIS/Typecheck.hs b/src/HSVIS/Typecheck.hs
index 23fb961..2b05793 100644
--- a/src/HSVIS/Typecheck.hs
+++ b/src/HSVIS/Typecheck.hs
@@ -3,25 +3,27 @@
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TupleSections #-}
 module HSVIS.Typecheck where
 
 import Control.Monad
-import Control.Monad.Reader
-import Control.Monad.State
-import Control.Monad.Writer.CPS
+import Data.Bifunctor (first)
 import Data.Foldable (toList)
+import Data.List (partition)
 import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as Map
 
 import Data.Bag
 import Data.List.NonEmpty.Util
 import HSVIS.AST
 import HSVIS.Parser
 import HSVIS.Diagnostic
+import HSVIS.Pretty
 
 
 data StageTC
 
-type instance X DataDef StageTC = CType
+type instance X DataDef StageTC = ()
 type instance X FunDef  StageTC = CType
 type instance X FunEq   StageTC = CType
 type instance X Kind    StageTC = ()
@@ -30,8 +32,8 @@ type instance X Pattern StageTC = CType
 type instance X RHS     StageTC = CType
 type instance X Expr    StageTC = CType
 
-data instance E Type StageTC = TUniVar Int
-  deriving (Show)
+data instance E Type StageTC = TUniVar Int deriving (Show)
+data instance E Kind StageTC = KUniVar Int deriving (Show)
 
 type CProgram = Program StageTC
 type CDataDef = DataDef StageTC
@@ -54,8 +56,8 @@ type instance X Pattern StageTyped = TType
 type instance X RHS     StageTyped = TType
 type instance X Expr    StageTyped = TType
 
-data instance E t StageTyped
-  deriving (Show)
+data instance E Type StageTyped deriving (Show)
+data instance E Kind StageTyped deriving (Show)
 
 type TProgram = Program StageTyped
 type TDataDef = DataDef StageTyped
@@ -68,77 +70,203 @@ type TRHS     = RHS     StageTyped
 type TExpr    = Expr    StageTyped
 
 
-typecheck :: FilePath -> String -> Program Range -> ([Diagnostic], Program TType)
+typecheck :: FilePath -> String -> PProgram -> ([Diagnostic], Program TType)
 typecheck fp source prog =
-  let (progtc, (ds1, cs)) =
-        runWriter
-        . flip evalStateT (Env mempty mempty)
-        . flip evalStateT 1
-        . flip runReaderT (fp, source)
-        . runTCM
-        $ tcProgram prog
+  let (ds1, cs, _, _, progtc) =
+        runTCM (tcProgram prog) (fp, source) 1 (Env mempty mempty)
       (ds2, sub) = solveConstrs cs
   in (toList (ds1 <> ds2), substProg sub progtc)
 
-data Constr =
-  CEq CType CType Range  -- ^ These types must be equal because of the expression here
+data Constr
+  = CEq CType CType Range  -- ^ These types must be equal because of the expression here
+  | CEqK CKind CKind Range  -- ^ These kinds must be equal because of the type here
   deriving (Show)
 
 data Env = Env (Map Name CKind) (Map Name CType)
   deriving (Show)
 
-newtype TCM a = TCM { runTCM ::
-    ReaderT (FilePath, String)
-    (StateT Int
-    (StateT Env
-    (Writer (Bag Diagnostic, Bag Constr))))
-    a }
-  deriving newtype (Functor, Applicative, Monad)
+newtype TCM a = TCM {
+  runTCM :: (FilePath, String)  -- ^ reader context: file and file contents
+         -> Int  -- ^ state: next id to generate
+         -> Env  -- ^ state: type and value environment
+         -> (Bag Diagnostic  -- ^ writer: diagnostics
+            ,Bag Constr      -- ^ writer: constraints
+            ,Int, Env, a)
+  }
+
+instance Functor TCM where
+  fmap f (TCM g) = TCM $ \ctx i env ->
+    let (ds, cs, i', env', x) = g ctx i env
+    in (ds, cs, i', env', f x)
+
+instance Applicative TCM where
+  pure x = TCM $ \_ i env -> (mempty, mempty, i, env, x)
+  (<*>) = ap
+
+instance Monad TCM where
+  TCM f >>= g = TCM $ \ctx i1 env1 ->
+    let (ds2, cs2, i2, env2, x) = f ctx i1 env1
+        (ds3, cs3, i3, env3, y) = runTCM (g x) ctx i2 env2
+    in (ds2 <> ds3, cs2 <> cs3, i3, env3, y)
 
 raise :: Range -> String -> TCM ()
-raise rng@(Range (Pos y _) _) msg = do
-  (fp, source) <- ask
-  TCM $ lift $ lift $ tell (pure (Diagnostic fp rng [] (source !! y) msg), mempty)
+raise rng@(Range (Pos y _) _) msg = TCM $ \(fp, source) i env ->
+  (pure (Diagnostic fp rng [] (lines source !! y) msg), mempty, i, env, ())
+
+emit :: Constr -> TCM ()
+emit c = TCM $ \_ i env -> (mempty, pure c, i, env, ())
+
+collectConstraints :: (Constr -> Maybe b) -> TCM a -> TCM (Bag b, a)
+collectConstraints predicate (TCM f) = TCM $ \ctx i env ->
+  let (ds, cs, i', env', x) = f ctx i env
+      (yes, no) = bagPartition predicate cs
+  in (ds, no, i', env', (yes, x))
+
+getFullEnv :: TCM Env
+getFullEnv = TCM $ \_ i env -> (mempty, mempty, i, env, env)
+
+putFullEnv :: Env -> TCM ()
+putFullEnv env = TCM $ \_ i _ -> (mempty, mempty, i, env, ())
+
+genId :: TCM Int
+genId = TCM $ \_ i env -> (mempty, mempty, i, env, i)
+
+getKind :: Name -> TCM (Maybe CKind)
+getKind name = do
+  Env tenv _ <- getFullEnv
+  return (Map.lookup name tenv)
+
+getType :: Name -> TCM (Maybe CType)
+getType name = do
+  Env _ venv <- getFullEnv
+  return (Map.lookup name venv)
 
 modifyTEnv :: (Map Name CKind -> Map Name CKind) -> TCM ()
-modifyTEnv f = TCM $ lift $ lift $ modify (\(Env a b) -> Env (f a) b)
+modifyTEnv f = do
+  Env tenv venv <- getFullEnv
+  putFullEnv (Env (f tenv) venv)
 
 modifyVEnv :: (Map Name CType -> Map Name CType) -> TCM ()
-modifyVEnv f = TCM $ lift $ lift $ modify (\(Env a b) -> Env a (f b))
+modifyVEnv f = do
+  Env tenv venv <- getFullEnv
+  putFullEnv (Env tenv (f venv))
+
+scopeTEnv :: TCM a -> TCM a
+scopeTEnv m = do
+  Env origtenv _ <- getFullEnv
+  res <- m
+  modifyTEnv (\_ -> origtenv)
+  return res
+
+scopeVEnv :: TCM a -> TCM a
+scopeVEnv m = do
+  Env _ origvenv <- getFullEnv
+  res <- m
+  modifyVEnv (\_ -> origvenv)
+  return res
+
+genKUniVar :: TCM CKind
+genKUniVar = KExt () . KUniVar <$> genId
 
 genUniVar :: CKind -> TCM CType
-genUniVar k = TCM $ lift $ state (\i -> (TExt k (TUniVar i), i + 1))
+genUniVar k = TExt k . TUniVar <$> genId
+
+getKind' :: Range -> Name -> TCM CKind
+getKind' rng name = getKind name >>= \case
+  Nothing -> do
+    raise rng $ "Type not in scope: " ++ pretty name
+    genKUniVar
+  Just k -> return k
+
+getType' :: Range -> Name -> TCM CType
+getType' rng name = getType name >>= \case
+  Nothing -> do
+    raise rng $ "Variable not in scope: " ++ pretty name
+    genUniVar (KType ())
+  Just k -> return k
 
 tcProgram :: PProgram -> TCM CProgram
 tcProgram (Program ddefs fdefs) = do
-  -- TODO: add preliminary kinds for the data definitions to the environment,
-  -- then solve for the kind variables in checkDataDef
+  (kconstrs, ddefs') <- collectConstraints isCEqK $ do
+    mapM_ prepareDataDef ddefs
+    mapM tcDataDef ddefs
+
+  solveKindVars kconstrs
+
+  fdefs' <- mapM tcFunDef fdefs
+
+  return (Program ddefs' fdefs')
+
+prepareDataDef :: PDataDef -> TCM ()
+prepareDataDef (DataDef _ name params _) = do
+  parkinds <- mapM (\_ -> genKUniVar) params
+  let k = foldr (KFun ()) (KType ()) parkinds
+  modifyTEnv (Map.insert name k)
+
+-- Assumes that the kind of the name itself has already been registered with
+-- the correct arity (this is doen by prepareDataDef).
+tcDataDef :: PDataDef -> TCM CDataDef
+tcDataDef (DataDef rng name params cons) = do
+  kd <- getKind' rng name
+  let (pkinds, kret) = splitKind kd
+
+  -- sanity checking; would be nicer to store these in prepareDataDef already
+  when (length pkinds /= length params) $ error "tcDataDef: Invalid param kind list length"
+  case kret of Right () -> return ()
+               _ -> error "tcDataDef: Invalid ret kind"
+
+  cons' <- scopeTEnv $ do
+    modifyTEnv (Map.fromList (zip (map snd params) pkinds) <>)
+    mapM (\(cname, ty) -> (cname,) <$> mapM kcType ty) cons
+  return (DataDef () name (zip pkinds (map snd params)) cons')
 
-  Program <$> traverse checkDataDef ddefs <*> traverse tcFunDef fdefs
+kcType :: PType -> TCM CType
+kcType = \case
+  TApp rng t ts -> do
+    t' <- kcType t
+    ts' <- mapM kcType ts
+    retk <- genKUniVar
+    let expected = foldr (KFun ()) retk (map extOf ts')
+    emit $ CEqK (extOf t') expected rng
+    return (TApp retk t' ts')
 
-checkDataDef :: PDataDef -> TCM CDataDef
-checkDataDef (DataDef rng name params cons) = do
-  _
+  TTup _ ts -> do
+    ts' <- mapM kcType ts
+    forM_ (zip (map extOf ts) ts') $ \(trng, ct) ->
+      emit $ CEqK (extOf ct) (KType ()) trng
+    return (TTup (KType ()) ts')
+
+  TList _ t -> do
+    t' <- kcType t
+    emit $ CEqK (extOf t') (KType ()) (extOf t)
+    return (TList (KType ()) t')
+
+  TFun _ t1 t2 -> do
+    t1' <- kcType t1
+    t2' <- kcType t2
+    emit $ CEqK (extOf t1') (KType ()) (extOf t1)
+    emit $ CEqK (extOf t2') (KType ()) (extOf t2)
+    return (TFun (KType ()) t1' t2')
+
+  TCon rng n -> TCon <$> getKind' rng n <*> pure n
+
+  TVar rng n -> TVar <$> getKind' rng n <*> pure n
 
 tcFunDef :: PFunDef -> TCM CFunDef
-tcFunDef (FunDef rng name msig eqs) = do
+tcFunDef (FunDef _ name msig eqs) = do
   when (not $ allEq (fmap (length . funeqPats) eqs)) $
     raise (sconcatne (fmap extOf eqs)) "Function equations have differing numbers of arguments"
 
   typ <- case msig of
-    Just sig -> checkType sig
-    Nothing -> genUniVar (KType ())
+    TypeSig sig -> kcType sig
+    TypeSigExt NoTypeSig -> genUniVar (KType ())
 
-  _
+  eqs' <- mapM (tcFunEq typ) eqs
 
-checkType :: PType -> TCM CType
-checkType = \case
-  TApp r t ts -> _
-  TTup r ts -> _
-  TList r t -> _
-  TFun r s t -> _
-  TCon r n -> _
-  TVar r n -> _
+  return (FunDef typ name (TypeSig typ) eqs')
+
+tcFunEq :: CType -> PFunEq -> TCM CFunEq
+tcFunEq = _
 
 allEq :: (Eq a, Foldable t) => t a -> Bool
 allEq l = case toList l of
@@ -147,3 +275,12 @@ allEq l = case toList l of
 
 funeqPats :: FunEq t -> [Pattern t]
 funeqPats (FunEq _ _ pats _) = pats
+
+splitKind :: Kind s -> ([Kind s], Either (E Kind s) (X Kind s))
+splitKind (KType x) = ([], Right x)
+splitKind (KFun _ k1 k2) = first (k1:) (splitKind k2)
+splitKind (KExt _ e) = ([], Left e)
+
+isCEqK :: Constr -> Maybe (CKind, CKind, Range)
+isCEqK (CEqK k1 k2 rng) = Just (k1, k2, rng)
+isCEqK _ = Nothing