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Diffstat (limited to 'lore/Language/Bs/Eval.hs')
-rw-r--r-- | lore/Language/Bs/Eval.hs | 241 |
1 files changed, 0 insertions, 241 deletions
diff --git a/lore/Language/Bs/Eval.hs b/lore/Language/Bs/Eval.hs deleted file mode 100644 index 290170b..0000000 --- a/lore/Language/Bs/Eval.hs +++ /dev/null @@ -1,241 +0,0 @@ -{-# LANGUAGE FlexibleContexts #-} -{-# LANGUAGE ScopedTypeVariables #-} -{-# LANGUAGE RecordWildCards #-} -{-# LANGUAGE OverloadedStrings #-} -{-# LANGUAGE NoImplicitPrelude #-} -module Language.Bs.Eval ( - evalText -, evalFile -, runParseTest -, safeExec -, runASTinEnv -, basicEnv -, fileToEvalForm -, textToEvalForm -, getFileContents -) where - -import Control.Exception -import Control.Monad.Reader -import qualified Data.Map as Map -import Data.String -import qualified Data.Text as T -import qualified Data.Text.IO as TIO -import Language.Bs.Expr -import Language.Bs.Parser -import Language.Bs.Primitives -import Protolude -import System.Directory - -funcEnv :: Map.Map T.Text Expr -funcEnv = Map.fromList $ primEnv - <> [ ("read" , IFun $ IFunc $ unop readFn) - , ("parse", IFun $ IFunc $ unop parseFn) - , ("eval", IFun $ IFunc $ unop eval) - , ("show", IFun $ IFunc $ unop (return . Tape . ppexpr)) - ] - -basicEnv :: Env -basicEnv = Env Map.empty funcEnv - -readFn :: Expr -> Eval Expr -readFn (Tape txt) = lineToEvalForm txt -readFn val = throw $ TypeMismatch "read expects string, instead got:" val - -parseFn :: Expr -> Eval Expr -parseFn (Tape txt) = either (throw . ParseError . show) return $ readExpr txt -parseFn val = throw $ TypeMismatch "parse expects string, instead got:" val - -safeExec :: IO a -> IO (Either String a) -safeExec m = do - result <- Control.Exception.try m - case result of - Left (eTop :: SomeException) -> - case fromException eTop of - Just (enclosed :: LispError) -> - return $ Left (show enclosed) - Nothing -> - return $ Left (show eTop) - Right val -> - return $ Right val - -runASTinEnv :: Env -> Eval b -> IO b -runASTinEnv code action = runReaderT (unEval action) code - -lineToEvalForm :: T.Text -> Eval Expr -lineToEvalForm input = either (throw . ParseError . show ) eval $ readExpr input - -evalFile :: FilePath -> T.Text -> IO () -- program file -evalFile filePath fileExpr = (runASTinEnv basicEnv $ fileToEvalForm filePath fileExpr) >>= print - -fileToEvalForm :: FilePath -> T.Text -> Eval Expr -fileToEvalForm filePath input = either (throw . ParseError . show ) evalBody $ readExprFile filePath input - -runParseTest :: T.Text -> T.Text -- for view AST -runParseTest input = either (T.pack . show) (T.pack . show) $ readExpr input - -getFileContents :: FilePath -> IO T.Text -getFileContents fname = do - exists <- doesFileExist fname - if exists then TIO.readFile fname else return "File does not exist." - -textToEvalForm :: T.Text -> Eval Expr -textToEvalForm input = either (throw . ParseError . show ) evalBody $ readExpr input - -evalText :: T.Text -> IO () --REPL -evalText textExpr = do - res <- runASTinEnv basicEnv $ textToEvalForm textExpr - print res - -getVar :: Expr -> Eval Expr -getVar (Atom atom) = do - Env{..} <- ask - case Map.lookup atom (Map.union fenv env) of -- lookup, but prefer functions - Just x -> return x - Nothing -> throw $ UnboundVar atom -getVar n = throw $ TypeMismatch "failure to get variable: " n - -ensureAtom :: Expr -> Eval Expr -ensureAtom n@(Atom _) = return n -ensureAtom n@(List _) = throw $ TypeMismatch "got list" n -ensureAtom n = throw $ TypeMismatch "expected an atomic value" n - -extractVar :: Expr -> T.Text -extractVar (Atom atom) = atom -extractVar n = throw $ TypeMismatch "expected an atomic value" n - -getEven :: [t] -> [t] -getEven [] = [] -getEven (x:xs) = x : getOdd xs - -getOdd :: [t] -> [t] -getOdd [] = [] -getOdd (_:xs) = getEven xs - -applyFunc :: Expr -> [Expr] -> [Expr] -> Eval Expr -applyFunc expr params args = bindArgsEval params args expr - -bindArgsEval :: [Expr] -> [Expr] -> Expr -> Eval Expr -bindArgsEval params args expr = do - Env{..} <- ask - let newVars = zipWith (\a b -> (extractVar a,b)) params args - let (newEnv, newFenv) = Map.partition (not . isFunc) $ Map.fromList newVars - local (const $ Env (newEnv <> env) (newFenv <> fenv)) $ eval expr - -isFunc :: Expr -> Bool -isFunc (List ((Atom "lambda"):_)) = True -isFunc _ = False - -eval :: Expr -> Eval Expr -eval (List [Atom "dumpEnv", x]) = do - Env{..} <- ask - liftIO $ print $ toList env - liftIO $ print $ toList fenv - eval x - -eval (Numb i) = return $ Numb i -eval (Tape s) = return $ Tape s -eval (Bool b) = return $ Bool b -eval (List []) = return Nil -eval Nil = return Nil -eval n@(Atom _) = getVar n - -eval (List [Atom "showSF", rest]) = return . Tape . T.pack $ show rest -eval (List ((:) (Atom "showSF") rest)) = return . Tape . T.pack . show $ List rest - -eval (List [Atom "quote", val]) = return val - -eval (List [Atom "if", pred_, then_, else_]) = do - ifRes <- eval pred_ - case ifRes of - (Bool True) -> eval then_ - (Bool False) -> eval else_ - _ -> - throw $ BadSpecialForm "if's first arg must eval into a boolean" -eval (List ( (:) (Atom "if") _)) = - throw $ BadSpecialForm "(if <bool> <s-expr> <s-expr>)" - -eval (List [Atom "begin", rest]) = evalBody rest -eval (List ((:) (Atom "begin") rest )) = evalBody $ List rest - --- top-level define --- TODO: how to make this eval correctly? -eval (List [Atom "define", List (name:args), body]) = do - Env{..} <- ask - _ <- eval body - bindArgsEval (name:args) [body] name - -eval (List [Atom "define", name, body]) = do - Env{..} <- ask - _ <- eval body - bindArgsEval [name] [body] name - -eval (List [Atom "let", List pairs, expr]) = do - Env{..} <- ask - atoms <- mapM ensureAtom $ getEven pairs - vals <- mapM eval $ getOdd pairs - bindArgsEval atoms vals expr - -eval (List (Atom "let":_) ) = - throw $ BadSpecialForm "let function expects list of parameters and S-Expression body\n(let <pairs> <s-expr>)" - - -eval (List [Atom "lambda", List params, expr]) = do - ctx <- ask - return $ Func (IFunc $ applyFunc expr params) ctx -eval (List (Atom "lambda":_) ) = throw $ BadSpecialForm "lambda function expects list of parameters and S-Expression body\n(lambda <params> <s-expr>)" - - --- needed to get cadr, etc to work -eval (List [Atom "cdr", List [Atom "quote", List (_:xs)]]) = - return $ List xs -eval (List [Atom "cdr", arg@(List (x:xs))]) = - case x of - -- proxy for if the list can be evaluated - Atom _ -> do - val <- eval arg - eval $ List [Atom "cdr", val] - _ -> return $ List xs - - -eval (List [Atom "car", List [Atom "quote", List (x:_)]]) = - return $ x -eval (List [Atom "car", arg@(List (x:_))]) = - case x of - Atom _ -> do - val <- eval arg - eval $ List [Atom "car", val] - _ -> return $ x - - -eval (List ((:) x xs)) = do - Env{..} <- ask - funVar <- eval x - xVal <- mapM eval xs - case funVar of - (IFun (IFunc internalFn)) -> - internalFn xVal - - (Func (IFunc definedFn) (Env benv _)) -> - local (const $ Env benv fenv) $ definedFn xVal - - _ -> - throw $ NotFunction funVar - -updateEnv :: T.Text -> Expr -> Env -> Env -updateEnv var e@(IFun _) Env{..} = Env env $ Map.insert var e fenv -updateEnv var e@(Func _ _) Env{..} = Env env $ Map.insert var e fenv -updateEnv var e Env{..} = Env (Map.insert var e env) fenv - -evalBody :: Expr -> Eval Expr -evalBody (List [List ((:) (Atom "define") [Atom var, defExpr]), rest]) = do - evalVal <- eval defExpr - ctx <- ask - local (const $ updateEnv var evalVal ctx) $ eval rest - -evalBody (List ((:) (List ((:) (Atom "define") [Atom var, defExpr])) rest)) = do - evalVal <- eval defExpr - ctx <- ask - local (const $ updateEnv var evalVal ctx) $ evalBody $ List rest - -evalBody x = eval x |