core driver

README.md

@@ -23,7 +23,7 @@ $ cabal test --test-show-details=direct
 $ rlpc -ddump-eval examples/factorial.hs
 # Compile and evaluate t.hs, with evaluation info dumped to t.log
 $ rlpc -ddump-eval -l t.log t.hs
-# Print the raw structure describing the compiler options and die
+# Print the raw structure describing the compiler options
 # (option parsing still must succeed in order to print)
 $ rlpc -ddump-opts t.hs
 ```

app/CoreDriver.hs

@@ -0,0 +1,17 @@
+module CoreDriver
+    ( driver
+    )
+    where
+--------------------------------------------------------------------------------
+import Compiler.RLPC
+import Control.Monad
+
+import Core.Lex
+import Core.Parse
+import GM
+--------------------------------------------------------------------------------
+
+driver :: RLPCIO ()
+driver = forFiles_ $ \f ->
+    withSource f (lexCoreR >=> parseCoreProgR >=> evalProgR)
+

app/Main.hs

@@ -10,12 +10,16 @@ import Data.HashSet             qualified as S
 import Data.Text                (Text)
 import Data.Text                qualified as T
 import Data.Text.IO             qualified as TIO
+import Data.List
 import System.IO
 import System.Exit              (exitSuccess)
 import Core
 import TI
 import GM
 import Lens.Micro.Mtl
+
+import CoreDriver               qualified
+import RlpDriver                qualified
 ----------------------------------------------------------------------------------
 
 optParser :: ParserInfo RLPCOptions
@@ -37,9 +41,15 @@ options = RLPCOptions
     {- -d -}
     <*> fmap S.fromList # many # option debugFlagReader
         (  short 'd'
-        <> help "dump evaluation logs"
+        <> help "pass debug flags"
         <> metavar "DEBUG FLAG"
         )
+    {- -f -}
+    <*> fmap S.fromList # many # option compilerFlagReader
+        (  short 'f'
+        <> help "pass compilation flags"
+        <> metavar "COMPILATION FLAG"
+        )
     {- --evaluator, -e -}
     <*> option evaluatorReader
         (  long "evaluator"
@@ -55,11 +65,27 @@ options = RLPCOptions
                 \triggering the garbage collector"
         <> value 50
         )
+    <*> option languageReader
+        (  long "language"
+        <> short 'x'
+        )
     <*> some (argument str $ metavar "FILES...")
     where
         infixr 9 #
         f # x = f x
 
+languageReader :: ReadM Language
+languageReader = maybeReader $ \case
+    "rlp"   -> Just LanguageRlp
+    "core"  -> Just LanguageCore
+    _       -> Nothing
+
+debugFlagReader :: ReadM DebugFlag
+debugFlagReader = str
+
+compilerFlagReader :: ReadM CompilerFlag
+compilerFlagReader = str
+
 evaluatorReader :: ReadM Evaluator
 evaluatorReader = maybeReader $ \case
     "gm"  -> Just EvaluatorGM
@@ -69,82 +95,15 @@ evaluatorReader = maybeReader $ \case
 mmany :: (Alternative f, Monoid m) => f m -> f m
 mmany v = liftA2 (<>) v (mmany v)
 
-debugFlagReader :: ReadM DebugFlag
-debugFlagReader = maybeReader $ \case
-    "dump-eval"  -> Just DDumpEval
-    "dump-opts"  -> Just DDumpOpts
-    "dump-ast"   -> Just DDumpAST
-    _            -> Nothing
-
 ----------------------------------------------------------------------------------
 
--- temp
-data CompilerError = CompilerError String
-    deriving Show
-
-instance Exception CompilerError
-
 main :: IO ()
 main = do
     opts <- execParser optParser
-    (_, es) <- evalRLPCIO opts driver
-    forM_ es $ \ (CompilerError e) -> print $ "warning: " <> e
-    pure ()
+    void $ evalRLPCIO opts driver
 
-driver :: RLPCIO CompilerError ()
-driver = sequence_
-    [ dshowFlags
-    , ddumpAST
-    , ddumpEval
-    ]
-
-dshowFlags :: RLPCIO CompilerError ()
-dshowFlags = whenFlag flagDDumpOpts do
-    ask >>= liftIO . print
-
-ddumpAST :: RLPCIO CompilerError ()
-ddumpAST = whenFlag flagDDumpAST $ forFiles_ \o f -> do
-    liftIO $ withFile f ReadMode $ \h -> do
-        s <- TIO.hGetContents h
-        case parseProg o s of
-            Right (a,_) -> hPutStrLn stderr $ show a
-            Left e -> error "todo errors lol"
-
-ddumpEval :: RLPCIO CompilerError ()
-ddumpEval = whenFlag flagDDumpEval do
-    fs <- view rlpcInputFiles
-    forM_ fs $ \f -> liftIO (TIO.readFile f) >>= doProg
-
-    where
-        doProg :: Text -> RLPCIO CompilerError ()
-        doProg s = ask >>= \o -> case parseProg o s of
-            -- TODO: error handling
-            Left e -> addFatal . CompilerError $ show e
-            Right (a,_) -> do
-                log <- view rlpcLogFile
-                dumpEval <- chooseEval
-                case log of
-                    Just f  -> liftIO $ withFile f WriteMode $ dumpEval a
-                    Nothing -> liftIO $ dumpEval a stderr
-
-        -- choose the appropriate model based on the compiler opts
-        chooseEval = do
-            ev <- view rlpcEvaluator
-            pure $ case ev of
-                EvaluatorGM  -> v GM.hdbgProg
-                EvaluatorTI -> v TI.hdbgProg
-            where v f p h = f p h *> pure ()
-
-parseProg :: RLPCOptions
-          -> Text
-          -> Either SrcError (Program', [SrcError])
-parseProg o = evalRLPC o . (lexCore >=> parseCoreProg)
-
-forFiles_ :: (Monad m)
-          => (RLPCOptions -> FilePath -> RLPCT e m a)
-          -> RLPCT e m ()
-forFiles_ k = do
-    fs <- view rlpcInputFiles
-    o <- ask
-    forM_ fs (k o)
+driver :: RLPCIO ()
+driver = view rlpcLanguage >>= \case
+    LanguageCore -> CoreDriver.driver
+    LanguageRlp  -> RlpDriver.driver
 

app/RlpDriver.hs

@@ -0,0 +1,11 @@
+module RlpDriver
+    ( driver
+    )
+    where
+--------------------------------------------------------------------------------
+import Compiler.RLPC
+--------------------------------------------------------------------------------
+
+driver :: RLPCIO ()
+driver = undefined
+

rlp.cabal

@@ -38,8 +38,7 @@ library
                     , Rlp.Lex
                     , Rlp.Parse.Types
                     , Compiler.Types
-
-    other-modules:    Data.Heap
+                    , Data.Heap
                     , Data.Pretty
                     , Core.Parse
                     , Core.Lex
@@ -73,6 +72,7 @@ library
                     , semigroupoids
                     , comonad
                     , lens
+                    , text-ansi
 
     hs-source-dirs:   src
     default-language: GHC2021
@@ -85,8 +85,9 @@ library
 executable rlpc
     import:           warnings
     main-is:          Main.hs
-    -- other-modules:
-    -- other-extensions:
+    other-modules:    RlpDriver
+                    , CoreDriver
+
     build-depends: base >=4.17.0.0 && <4.20.0.0
                  , rlp
                  , optparse-applicative >= 0.18.1 && < 0.19

src/Compiler/RLPC.hs

@@ -11,31 +11,32 @@ errors and the family of RLPC monads.
 -- only used for mtl instances
 {-# LANGUAGE UndecidableInstances #-}
 {-# LANGUAGE DeriveGeneric, DerivingStrategies, DerivingVia #-}
+{-# LANGUAGE BlockArguments, ViewPatterns #-}
 module Compiler.RLPC
-    ( RLPC
-    , RLPCT(..)
-    , RLPCIO
-    , RLPCOptions(RLPCOptions)
-    , IsRlpcError(..)
-    , RlpcError(..)
-    , MsgEnvelope(..)
-    , addFatal
-    , addWound
-    , MonadErrorful
-    , Severity(..)
-    , Evaluator(..)
-    , evalRLPCT
-    , evalRLPCIO
-    , evalRLPC
-    , rlpcLogFile
-    , rlpcDFlags  
-    , rlpcEvaluator
-    , rlpcInputFiles
-    , DebugFlag(..)
-    , whenDFlag
-    , whenFFlag
-    , def
-    , liftErrorful
+    (
+    -- * Rlpc Monad transformer
+      RLPCT(RLPCT),
+    -- ** Special cases
+      RLPC, RLPCIO
+    -- ** Running
+    , runRLPCT
+    , evalRLPCT, evalRLPCIO, evalRLPC
+    -- * Rlpc options
+    , Language(..), Evaluator(..)
+    , DebugFlag(..), CompilerFlag(..)
+    -- ** Lenses
+    , rlpcLogFile, rlpcDFlags, rlpcEvaluator, rlpcInputFiles, rlpcLanguage
+    -- * Misc. MTL-style functions
+    , liftErrorful, hoistRlpcT
+    -- * Misc. Rlpc Monad -related types
+    , RLPCOptions(RLPCOptions), IsRlpcError(..), RlpcError(..)
+    , MsgEnvelope(..), Severity(..)
+    , addDebugMsg
+    , whenDFlag, whenFFlag
+    -- * Misc. Utilities
+    , forFiles_, withSource
+    -- * Convenient re-exports
+    , addFatal, addWound, def
     )
     where
 ----------------------------------------------------------------------------------
@@ -45,7 +46,9 @@ import Control.Monad
 import Control.Monad.Reader
 import Control.Monad.State      (MonadState(state))
 import Control.Monad.Errorful
+import Control.Monad.IO.Class
 import Compiler.RlpcError
+import Compiler.Types
 import Data.Functor.Identity
 import Data.Default.Class
 import Data.Foldable
@@ -55,19 +58,34 @@ import Data.Hashable            (Hashable)
 import Data.HashSet             (HashSet)
 import Data.HashSet             qualified as S
 import Data.Coerce
+import Data.Text                (Text)
+import Data.Text                qualified as T
+import Data.Text.IO             qualified as T
+import Text.ANSI                qualified as Ansi
+import Text.PrettyPrint         hiding ((<>))
 import Lens.Micro.Platform
+import Lens.Micro.Platform.Internal
 import System.Exit
 ----------------------------------------------------------------------------------
 
 newtype RLPCT m a = RLPCT {
         runRLPCT :: ReaderT RLPCOptions (ErrorfulT (MsgEnvelope RlpcError) m) a
     }
-    deriving (Functor, Applicative, Monad, MonadReader RLPCOptions)
+    deriving ( Functor, Applicative, Monad
+             , MonadReader RLPCOptions, MonadErrorful (MsgEnvelope RlpcError))
+
+rlpc :: (IsRlpcError e, Monad m)
+     => (RLPCOptions -> (Maybe a, [MsgEnvelope e]))
+     -> RLPCT m a
+rlpc f = RLPCT . ReaderT $ \opt ->
+    ErrorfulT . pure $ f opt & _2 . each . mapped %~ liftRlpcError
 
 type RLPC = RLPCT Identity
 
 type RLPCIO = RLPCT IO
 
+instance (MonadIO m) => MonadIO (RLPCT m) where
+
 evalRLPC :: RLPCOptions
          -> RLPC a
          -> (Maybe a, [MsgEnvelope RlpcError])
@@ -75,32 +93,28 @@ evalRLPC opt r = runRLPCT r
                & flip runReaderT opt
                & runErrorful
 
-evalRLPCT :: (Monad m)
-          => RLPCOptions
+evalRLPCT :: RLPCOptions
           -> RLPCT m a
           -> m (Maybe a, [MsgEnvelope RlpcError])
-evalRLPCT = undefined
-
-evalRLPCIO :: RLPCOptions -> RLPCIO a -> IO a
-evalRLPCIO opt r = do
-    (ma,es) <- evalRLPCT opt r
-    putRlpcErrs es
-    case ma of
-        Just x  -> pure x
-        Nothing -> die "Failed, no code compiled."
-
-putRlpcErrs :: [MsgEnvelope RlpcError] -> IO ()
-putRlpcErrs = traverse_ print
+evalRLPCT opt r = runRLPCT r
+                & flip runReaderT opt
+                & runErrorfulT
 
 liftErrorful :: (Monad m, IsRlpcError e) => ErrorfulT (MsgEnvelope e) m a -> RLPCT m a
 liftErrorful e = RLPCT $ lift (fmap liftRlpcError `mapErrorful` e)
 
+hoistRlpcT :: (forall a. m a -> n a)
+         -> RLPCT m a -> RLPCT n a
+hoistRlpcT f rma = RLPCT $ ReaderT $ \opt ->
+    ErrorfulT $ f $ evalRLPCT opt rma
+
 data RLPCOptions = RLPCOptions
     { _rlpcLogFile     :: Maybe FilePath
     , _rlpcDFlags      :: HashSet DebugFlag
     , _rlpcFFlags      :: HashSet CompilerFlag
     , _rlpcEvaluator   :: Evaluator
     , _rlpcHeapTrigger :: Int
+    , _rlpcLanguage    :: Language
     , _rlpcInputFiles  :: [FilePath]
     }
     deriving Show
@@ -108,6 +122,9 @@ data RLPCOptions = RLPCOptions
 data Evaluator = EvaluatorGM | EvaluatorTI
     deriving Show
 
+data Language = LanguageRlp | LanguageCore
+    deriving Show
+
 ----------------------------------------------------------------------------------
 
 instance Default RLPCOptions where
@@ -118,16 +135,20 @@ instance Default RLPCOptions where
         , _rlpcEvaluator = EvaluatorGM
         , _rlpcHeapTrigger = 200
         , _rlpcInputFiles = []
+        , _rlpcLanguage = LanguageRlp
         }
 
 -- debug flags are passed with -dFLAG
-type DebugFlag = String
+type DebugFlag = Text
 
-type CompilerFlag = String
+type CompilerFlag = Text
 
 makeLenses ''RLPCOptions
 pure []
 
+addDebugMsg :: (Monad m, IsText e) => Text -> e -> RLPCT m ()
+addDebugMsg tag e = addWound . debugMsg tag $ Text [e ^. unpacked . packed]
+
 -- TODO: rewrite this with prisms once microlens-pro drops :3
 whenDFlag :: (Monad m) => DebugFlag -> RLPCT m () -> RLPCT m ()
 whenDFlag f m = do
@@ -143,3 +164,75 @@ whenFFlag f m = do
     let a = S.member f fs
     when a m
 
+--------------------------------------------------------------------------------
+
+evalRLPCIO :: RLPCOptions -> RLPCIO a -> IO a
+evalRLPCIO opt r = do
+    (ma,es) <- evalRLPCT opt r
+    putRlpcErrs opt es
+    case ma of
+        Just x  -> pure x
+        Nothing -> die "Failed, no code compiled."
+
+putRlpcErrs :: RLPCOptions -> [MsgEnvelope RlpcError] -> IO ()
+putRlpcErrs opts = filter byTag
+               >>> traverse_ (putStrLn . ('\n':) . prettyRlpcMsg)
+    where
+        dflags = opts ^. rlpcDFlags
+
+        byTag :: MsgEnvelope RlpcError -> Bool
+        byTag (view msgSeverity -> SevDebug t) =
+            t `S.member` dflags
+
+prettyRlpcMsg :: MsgEnvelope RlpcError -> String
+prettyRlpcMsg m@(view msgSeverity -> SevDebug _) = prettyRlpcDebugMsg m
+prettyRlpcMsg m                                  = render $ docRlpcErr m
+
+prettyRlpcDebugMsg :: MsgEnvelope RlpcError -> String
+prettyRlpcDebugMsg msg =
+        T.unpack . foldMap mkLine $ [ t' | t <- ts, t' <- T.lines t ]
+    where
+        mkLine s = "-d" <> tag <> ": " <> s <> "\n"
+        Text ts = msg ^. msgDiagnostic
+        SevDebug tag = msg ^. msgSeverity
+
+docRlpcErr :: MsgEnvelope RlpcError -> Doc
+docRlpcErr msg = header
+                 $$ nest 2 bullets
+                 $$ source
+    where
+        source = vcat $ zipWith (<+>) rule srclines
+            where
+                rule = repeat (ttext . Ansi.blue . Ansi.bold $ "|")
+                srclines = ["", "<problematic source code>", ""]
+        filename = msgColour "<input>"
+        pos = msgColour $ tshow (msg ^. msgSpan . srcspanLine)
+                       <> ":"
+                       <> tshow (msg ^. msgSpan . srcspanColumn)
+
+        header = ttext $ filename <> msgColour ":" <> pos <> msgColour ": "
+                        <> errorColour "error" <> msgColour ":"
+
+        bullets = let Text ts = msg ^. msgDiagnostic
+                  in vcat $ hang "•" 2 . ttext . msgColour <$> ts
+
+        msgColour = Ansi.white . Ansi.bold
+        errorColour = Ansi.red . Ansi.bold
+        ttext = text . T.unpack
+        tshow :: (Show a) => a -> Text
+        tshow = T.pack . show
+
+--------------------------------------------------------------------------------
+
+forFiles_ :: (Monad m)
+          => (FilePath -> RLPCT m a)
+          -> RLPCT m ()
+forFiles_ k = do
+    fs <- view rlpcInputFiles
+    forM_ fs k
+
+-- TODO: catch any exceptions, i.e. non-existent files should be handled by the
+-- compiler
+withSource :: (MonadIO m) => FilePath -> (Text -> RLPCT m a) -> RLPCT m a
+withSource f k = liftIO (T.readFile f) >>= k
+

src/Compiler/RlpcError.hs

@@ -10,6 +10,7 @@ module Compiler.RlpcError
     , msgSeverity
     , liftRlpcErrors
     , errorMsg
+    , debugMsg
     -- * Located Comonad
     , Located(..)
     , SrcSpan(..)
@@ -46,6 +47,7 @@ instance IsRlpcError RlpcError where
 
 data Severity = SevWarning
               | SevError
+              | SevDebug Text
               deriving Show
 
 makeLenses ''MsgEnvelope
@@ -65,3 +67,11 @@ errorMsg s e = MsgEnvelope
     , _msgSeverity = SevError
     }
 
+debugMsg :: Text -> e -> MsgEnvelope e
+debugMsg tag e = MsgEnvelope
+    -- TODO: not pretty, but it is a debug message after all
+    { _msgSpan = SrcSpan 0 0 0 0
+    , _msgDiagnostic = e
+    , _msgSeverity = SevDebug tag
+    }
+

src/Compiler/Types.hs

@@ -1,5 +1,6 @@
 module Compiler.Types
     ( SrcSpan(..)
+    , srcspanLine, srcspanColumn, srcspanAbs, srcspanLen
     , Located(..)
     , (<<~), (<~>)
 
@@ -13,6 +14,7 @@ module Compiler.Types
 import Control.Comonad
 import Data.Functor.Apply
 import Data.Functor.Bind
+import Control.Lens             hiding ((<<~))
 --------------------------------------------------------------------------------
 
 -- | Token wrapped with a span (line, column, absolute, length)
@@ -39,6 +41,16 @@ data SrcSpan = SrcSpan
     !Int -- ^ Length
     deriving Show
 
+tupling :: Iso' SrcSpan (Int, Int, Int, Int)
+tupling = iso (\ (SrcSpan a b c d) -> (a,b,c,d))
+              (\ (a,b,c,d) -> SrcSpan a b c d)
+
+srcspanLine, srcspanColumn, srcspanAbs, srcspanLen :: Lens' SrcSpan Int
+srcspanLine = tupling . _1
+srcspanColumn = tupling . _2
+srcspanAbs = tupling . _3
+srcspanLen = tupling . _4
+
 instance Semigroup SrcSpan where
     SrcSpan la ca aa sa <> SrcSpan lb cb ab sb = SrcSpan l c a s where
         l = min la lb

src/Control/Monad/Errorful.hs

@@ -1,11 +1,11 @@
-{-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE FunctionalDependencies #-}
-{-# LANGUAGE TupleSections, PatternSynonyms #-}
+{-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE UndecidableInstances #-}
 module Control.Monad.Errorful
-    ( ErrorfulT
-    , runErrorfulT
+    ( ErrorfulT(..)
     , Errorful
+    , pattern Errorful
+    , errorful
     , runErrorful
     , mapErrorful
     , MonadErrorful(..)
@@ -13,6 +13,7 @@ module Control.Monad.Errorful
     where
 ----------------------------------------------------------------------------------
 import Control.Monad.State.Strict
+import Control.Monad.Reader
 import Control.Monad.Trans
 import Data.Functor.Identity
 import Data.Coerce
@@ -28,6 +29,9 @@ type Errorful e = ErrorfulT e Identity
 pattern Errorful :: (Maybe a, [e]) -> Errorful e a
 pattern Errorful a = ErrorfulT (Identity a)
 
+errorful :: (Applicative m) => (Maybe a, [e]) -> ErrorfulT e m a
+errorful = ErrorfulT . pure
+
 runErrorful :: Errorful e a -> (Maybe a, [e])
 runErrorful m = coerce (runErrorfulT m)
 
@@ -67,13 +71,13 @@ mapErrorful f (ErrorfulT m) = ErrorfulT $
     m & mapped . _2 . mapped %~ f
 
 -- when microlens-pro drops we can write this as
---    mapErrorful f = coerced . mapped . _2 . mappd %~ f
+--    mapErrorful f = coerced . mapped . _2 . mapped %~ f
 -- lol
 
 --------------------------------------------------------------------------------
 -- daily dose of n^2 instances
 
-instance (Monad m, MonadErrorful e m) => MonadErrorful e (StateT s m) where
-    addWound = undefined
-    addFatal = undefined
+instance (Monad m, MonadErrorful e m) => MonadErrorful e (ReaderT r m) where
+    addWound = lift . addWound
+    addFatal = lift . addFatal
 

src/Core/HindleyMilner.hs

@@ -105,7 +105,7 @@ checkCoreProg p = scDefs
              where scname = sc ^. _lhs._1
 
 -- | @checkCoreProgR p@ returns @p@ if @p@ successfully typechecks.
-checkCoreProgR :: Program' -> RLPC Program'
+checkCoreProgR :: (Applicative m) => Program' -> RLPCT m Program'
 checkCoreProgR p = undefined
 
 {-# WARNING checkCoreProgR "unimpl" #-}

src/Core/Lex.x

@@ -20,6 +20,7 @@ import Debug.Trace
 import Data.Text            (Text)
 import Data.Text            qualified as T
 import Data.String          (IsString(..))
+import Data.Functor.Identity
 import Core.Syntax
 import Compiler.RLPC
 -- TODO: unify Located definitions
@@ -180,8 +181,11 @@ lexCore s = case m of
     where
         m = runAlex s lexStream
 
-lexCoreR :: Text -> RLPC [Located CoreToken]
-lexCoreR = lexCore
+lexCoreR :: forall m. (Applicative m) => Text -> RLPCT m [Located CoreToken]
+lexCoreR = hoistRlpcT generalise . lexCore
+    where
+        generalise :: forall a. Identity a -> m a
+        generalise (Identity a) = pure a
 
 -- | @lexCore@, but the tokens are stripped of location info. Useful for
 -- debugging

src/Core/Parse.y

@@ -17,9 +17,11 @@ module Core.Parse
 
 import Control.Monad        ((>=>))
 import Data.Foldable        (foldl')
+import Data.Functor.Identity
 import Core.Syntax
 import Core.Lex
 import Compiler.RLPC
+import Control.Monad
 import Lens.Micro
 import Data.Default.Class   (def)
 import Data.Hashable        (Hashable)
@@ -224,8 +226,16 @@ insScDef sc = programScDefs %~ (sc:)
 singletonScDef :: (Hashable b) => ScDef b -> Program b
 singletonScDef sc = insScDef sc mempty
 
-parseCoreProgR :: [Located CoreToken] -> RLPC Program'
-parseCoreProgR = parseCoreProg
+parseCoreProgR :: forall m. (Monad m) => [Located CoreToken] -> RLPCT m Program'
+parseCoreProgR = ddumpast <=< (hoistRlpcT generalise . parseCoreProg)
+    where
+        generalise :: forall a. Identity a -> m a
+        generalise (Identity a) = pure a
+
+        ddumpast :: Program' -> RLPCT m Program'
+        ddumpast p = do
+            addDebugMsg "dump-ast" . show $ p
+            pure p
 
 happyBind :: RLPC a -> (a -> RLPC b) -> RLPC b
 happyBind m k = m >>= k

src/Core/Syntax.hs

@@ -103,7 +103,7 @@ data Binding b = Binding b (Expr b)
 deriving instance (Eq b) => Eq (Binding b)
 
 infixl 1 :=
-pattern (:=) :: b -> (Expr b) -> (Binding b)
+pattern (:=) :: b -> Expr b -> Binding b
 pattern k := v = Binding k v
 
 data Alter b = Alter AltCon [b] (Expr b)
@@ -123,7 +123,7 @@ data AltCon = AltData Name
             | Default
             deriving (Show, Read, Eq, Lift)
 
-data Lit = IntL Int
+newtype Lit = IntL Int
     deriving (Show, Read, Eq, Lift)
 
 type Name = T.Text
@@ -201,7 +201,7 @@ instance HasLHS (Alter b) (Alter b) (AltCon, [b]) (AltCon, [b]) where
 instance HasLHS (ScDef b) (ScDef b) (b, [b]) (b, [b]) where
     _lhs = lens
         (\ (ScDef n as _) -> (n,as))
-        (\ (ScDef _ _ e) (n',as') -> (ScDef n' as' e))
+        (\ (ScDef _ _ e) (n',as') -> ScDef n' as' e)
 
 instance HasLHS (Binding b) (Binding b) b b where
     _lhs = lens

src/GM.hs

@@ -8,6 +8,7 @@ Description : The G-Machine
 module GM
     ( hdbgProg
     , evalProg
+    , evalProgR
     , Node(..)
     , gmEvalProg
     , finalStateOf
@@ -34,6 +35,7 @@ import System.IO                    (Handle, hPutStrLn)
 import Data.String                  (IsString)
 import Data.Heap
 import Debug.Trace
+import Compiler.RLPC
 import Core2Core
 import Core
 ----------------------------------------------------------------------------------
@@ -156,6 +158,21 @@ hdbgProg p hio = do
         [resAddr] = final ^. gmStack
         res = hLookupUnsafe resAddr h
 
+evalProgR :: (Monad m) => Program' -> RLPCT m (Node, Stats)
+evalProgR p = do
+    (renderOut . showState) `traverse_` states
+    renderOut . showStats $ sts
+    pure (res, sts)
+    where
+        renderOut r = addDebugMsg "dump-eval" $ render r ++ "\n"
+        states = eval . compile $ p
+        final = last states
+
+        sts = final ^. gmStats
+        -- the address of the result should be the one and only stack entry
+        [resAddr] = final ^. gmStack
+        res = hLookupUnsafe resAddr (final ^. gmHeap)
+
 eval :: GmState -> [GmState]
 eval st = st : rest
     where

src/Rlp/Lex.x

@@ -11,6 +11,8 @@ module Rlp.Lex
     , lexDebug
     , lexCont
     , popLexState
+    , programInitState
+    , runP'
     )
     where
 import Codec.Binary.UTF8.String (encodeChar)
@@ -236,27 +238,9 @@ alexEOF = do
     pos <- getPos
     pure (Located (spanFromPos pos 0) TokenEOF)
 
-initParseState :: Text -> ParseState
-initParseState s = ParseState
-    { _psLayoutStack = []
-    -- IMPORTANT: the initial state is `bol` to begin the top-level layout,
-    -- which then returns to state 0 which continues the normal lexing process.
-    , _psLexState = [layout_top,0]
-    , _psInput = initAlexInput s
-    , _psOpTable = mempty
-    }
-
-initAlexInput :: Text -> AlexInput
-initAlexInput s = AlexInput
-    { _aiPrevChar   = '\0'
-    , _aiSource     = s
-    , _aiBytes      = []
-    , _aiPos        = (1,1,0)
-    }
-
 runP' :: P a -> Text -> (ParseState, [MsgEnvelope RlpParseError], Maybe a)
 runP' p s = runP p st where
-    st = initParseState s
+    st = initParseState [layout_top,0] s
 
 lexToken :: P (Located RlpToken)
 lexToken = do
@@ -310,7 +294,7 @@ popLayout = do
     psLayoutStack %= (drop 1)
     case ctx of
         Just l      -> pure l
-        Nothing     -> error "uhh"
+        Nothing     -> error "popLayout: layout stack empty! this is a bug."
 
 pushLayout :: Layout -> P ()
 pushLayout l = do
@@ -368,10 +352,13 @@ explicitRBrace inp l = do
 doLayout :: LexerAction (Located RlpToken)
 doLayout _ _ = do
     i <- indentLevel
-    traceM $ "doLayout: i: " <> show i
+    -- traceM $ "doLayout: i: " <> show i
     pushLayout (Implicit i)
     popLexState
     insertLBrace
 
+programInitState :: Text -> ParseState
+programInitState = initParseState [layout_top,0]
+
 }
 

src/Rlp/Parse.y

@@ -2,10 +2,13 @@
 {-# LANGUAGE LambdaCase, ViewPatterns #-}
 module Rlp.Parse
     ( parseRlpProg
+    , parseRlpProgR
     , parseRlpExpr
+    , parseRlpExprR
     )
     where
 import Compiler.RlpcError
+import Compiler.RLPC
 import Rlp.Lex
 import Rlp.Syntax
 import Rlp.Parse.Types
@@ -19,6 +22,7 @@ import Data.Functor.Bind
 import Control.Comonad
 import Data.Functor
 import Data.Semigroup.Traversable
+import Data.Text                    (Text)
 import Data.Text                    qualified as T
 import Data.Void
 }
@@ -29,6 +33,7 @@ import Data.Void
 %monad { P }
 %lexer { lexCont } { Located _ TokenEOF }
 %error { parseError }
+%errorhandlertype explist
 %tokentype { Located RlpToken }
 
 %token
@@ -85,6 +90,7 @@ DeclsV              :: { [Decl' RlpcPs] }
 DeclsV              : Decl VS Decls         { $1 : $3 }
                     | Decl VS               { [$1] }
                     | Decl                  { [$1] }
+                    | {- epsilon -}         { [] }
 
 VS                  :: { Located RlpToken }
 VS                  : ';'                   { $1 }
@@ -187,6 +193,13 @@ Con         :: { Located PsName }
 
 {
 
+parseRlpExprR = undefined
+
+parseRlpProgR :: (Monad m) => Text -> RLPCT m (RlpProgram RlpcPs)
+parseRlpProgR s = liftErrorful $ pToErrorful parseRlpProg st
+    where
+        st = programInitState s
+
 mkPsName :: Located RlpToken -> Located PsName
 mkPsName = fmap extractName
 
@@ -207,9 +220,9 @@ mkProgram ds = do
     pt <- use psOpTable
     pure $ RlpProgram (associate pt <$> ds)
 
-parseError :: Located RlpToken -> P a
-parseError (Located ss t) = addFatal $
-    errorMsg ss RlpParErrUnexpectedToken
+parseError :: (Located RlpToken, [String]) -> P a
+parseError ((Located ss t), exp) = addFatal $
+    errorMsg ss (RlpParErrUnexpectedToken t exp)
 
 mkInfixD :: Assoc -> Int -> PsName -> P (Decl' RlpcPs)
 mkInfixD a p n = do
@@ -228,3 +241,4 @@ intOfToken :: Located RlpToken -> Int
 intOfToken (Located _ (TokenLitInt n)) = n
 
 }
+

src/Rlp/Parse/Types.hs

@@ -8,6 +8,8 @@ module Rlp.Parse.Types
 
     -- * Parser monad and state
     , P(..), ParseState(..), Layout(..), OpTable, OpInfo
+    , initParseState, initAlexInput
+    , pToErrorful
     -- ** Lenses
     , psLayoutStack, psLexState, psInput, psOpTable
 
@@ -39,6 +41,7 @@ import Data.Functor.Classes
 import Data.HashMap.Strict          qualified as H
 import Data.Void
 import Data.Word                    (Word8)
+import Data.Text                    qualified as T
 import Lens.Micro.TH
 import Lens.Micro
 import Rlp.Syntax
@@ -145,6 +148,11 @@ newtype P a = P {
     }
     deriving (Functor)
 
+pToErrorful :: (Applicative m)
+            => P a -> ParseState -> ErrorfulT (MsgEnvelope RlpParseError) m a
+pToErrorful p st = ErrorfulT $ pure (ma,es) where
+    (_,es,ma) = runP p st
+
 instance Applicative P where
     pure a = P $ \st -> (st, [], pure a)
     liftA2 = liftM2
@@ -188,10 +196,28 @@ type OpInfo = (Assoc, Int)
 data RlpParseError = RlpParErrOutOfBoundsPrecedence Int
                    | RlpParErrDuplicateInfixD Name
                    | RlpParErrLexical
-                   | RlpParErrUnexpectedToken
-                   deriving (Eq, Ord, Show)
+                   | RlpParErrUnexpectedToken RlpToken [String]
+                   deriving (Show)
 
 instance IsRlpcError RlpParseError where
+    liftRlpcError = \case
+        RlpParErrOutOfBoundsPrecedence n ->
+            Text [ "Illegal precedence in infixity declaration"
+                 , "rl' currently only allows precedences between 0 and 9."
+                 ]
+        RlpParErrDuplicateInfixD s ->
+            Text [ "Conflicting infixity declarations for operator "
+                    <> tshow s
+                 ]
+        RlpParErrLexical ->
+            Text [ "Unknown lexical error :(" ]
+        RlpParErrUnexpectedToken t exp ->
+            Text [ "Unexpected token " <> tshow t
+                 , "Expected: " <> tshow exp
+                 ]
+        where
+            tshow :: (Show a) => a -> T.Text
+            tshow = T.pack . show
 
 ----------------------------------------------------------------------------------
 
@@ -224,3 +250,21 @@ addFatalHere l e = P $ \st ->
             }
     in (st, [e'], Nothing)
 
+initParseState :: [Int] -> Text -> ParseState
+initParseState ls s = ParseState
+    { _psLayoutStack = []
+    -- IMPORTANT: the initial state is `bol` to begin the top-level layout,
+    -- which then returns to state 0 which continues the normal lexing process.
+    , _psLexState = ls
+    , _psInput = initAlexInput s
+    , _psOpTable = mempty
+    }
+
+initAlexInput :: Text -> AlexInput
+initAlexInput s = AlexInput
+    { _aiPrevChar   = '\0'
+    , _aiSource     = s
+    , _aiBytes      = []
+    , _aiPos        = (1,1,0)
+    }
+