| 1 | import System.IO (hFlush, stdout) |
| 2 | import System.Environment (getArgs) |
| 3 | import Control.Monad (mapM) |
| 4 | import Control.Monad.Except (runExceptT) |
| 5 | import Control.Monad.Trans (liftIO) |
| 6 | import Data.Foldable (foldlM, foldrM) |
| 7 | |
| 8 | import Readline (readline, load_history) |
| 9 | import Types |
| 10 | import Reader (read_str) |
| 11 | import Printer (_pr_str) |
| 12 | import Env (env_new, env_bind, env_get, env_set) |
| 13 | import Core (ns) |
| 14 | |
| 15 | -- read |
| 16 | |
| 17 | mal_read :: String -> IOThrows MalVal |
| 18 | mal_read = read_str |
| 19 | |
| 20 | -- eval |
| 21 | |
| 22 | -- starts-with is replaced with pattern matching. |
| 23 | |
| 24 | qqIter :: Env -> MalVal -> [MalVal] -> IOThrows [MalVal] |
| 25 | qqIter env (MalSeq _ (Vect False) [MalSymbol "splice-unquote", x]) acc = do |
| 26 | evaluated <- eval env x |
| 27 | case evaluated of |
| 28 | MalSeq _ (Vect False) xs -> return $ xs ++ acc |
| 29 | _ -> throwStr "invalid splice-unquote argument" |
| 30 | qqIter _ (MalSeq _ (Vect False) (MalSymbol "splice-unquote" : _)) _ = throwStr "invalid splice-unquote" |
| 31 | qqIter env x acc = (: acc) <$> quasiquote x env |
| 32 | |
| 33 | quasiquote :: MalVal -> Env -> IOThrows MalVal |
| 34 | quasiquote (MalSeq _ (Vect False) [MalSymbol "unquote", x]) env = eval env x |
| 35 | -- FIXME This line |
| 36 | quasiquote (MalSeq m _ ys) env = MalSeq m (Vect False) <$> foldrM (qqIter env) [] ys |
| 37 | -- is adapted to broken tests. It should be: |
| 38 | -- quasiquote (MalSeq m v ys) env = MalSeq m v <$> foldrM (qqIter env) [] ys |
| 39 | quasiquote ast _ = return ast |
| 40 | |
| 41 | -- is-macro-call is replaced with pattern matching. |
| 42 | |
| 43 | macroexpand :: Env -> MalVal -> IOThrows MalVal |
| 44 | macroexpand env ast@(MalSeq _ (Vect False) (MalSymbol a0 : args)) = do |
| 45 | maybeMacro <- liftIO $ env_get env a0 |
| 46 | case maybeMacro of |
| 47 | Just (MalFunction {fn=f, macro=True}) -> macroexpand env =<< f args |
| 48 | _ -> return ast |
| 49 | macroexpand _ ast = return ast |
| 50 | |
| 51 | -- eval_ast is replaced with pattern matching. |
| 52 | |
| 53 | let_bind :: Env -> [MalVal] -> IOThrows () |
| 54 | let_bind _ [] = return () |
| 55 | let_bind env (MalSymbol b : e : xs) = do |
| 56 | liftIO . env_set env b =<< eval env e |
| 57 | let_bind env xs |
| 58 | let_bind _ _ = throwStr "invalid let*" |
| 59 | |
| 60 | unWrapSymbol :: MalVal -> IOThrows String |
| 61 | unWrapSymbol (MalSymbol s) = return s |
| 62 | unWrapSymbol _ = throwStr "fn* parameter must be symbols" |
| 63 | |
| 64 | newFunction :: MalVal -> Env -> [String] -> MalVal |
| 65 | newFunction a env p = MalFunction {f_ast=a, f_params=p, macro=False, meta=Nil, |
| 66 | fn=(\args -> do |
| 67 | fn_env <- liftIO $ env_new env |
| 68 | ok <- liftIO $ env_bind fn_env p args |
| 69 | case ok of |
| 70 | True -> eval fn_env a |
| 71 | False -> throwStr $ "actual parameters do not match signature " ++ show p)} |
| 72 | |
| 73 | apply_ast :: [MalVal] -> Env -> IOThrows MalVal |
| 74 | |
| 75 | apply_ast [] _ = return $ toList [] |
| 76 | |
| 77 | apply_ast [MalSymbol "def!", MalSymbol a1, a2] env = do |
| 78 | evd <- eval env a2 |
| 79 | liftIO $ env_set env a1 evd |
| 80 | return evd |
| 81 | apply_ast (MalSymbol "def!" : _) _ = throwStr "invalid def!" |
| 82 | |
| 83 | apply_ast [MalSymbol "let*", MalSeq _ _ params, a2] env = do |
| 84 | let_env <- liftIO $ env_new env |
| 85 | let_bind let_env params |
| 86 | eval let_env a2 |
| 87 | apply_ast (MalSymbol "let*" : _) _ = throwStr "invalid let*" |
| 88 | |
| 89 | apply_ast [MalSymbol "quote", a1] _ = return a1 |
| 90 | apply_ast (MalSymbol "quote" : _) _ = throwStr "invalid quote" |
| 91 | |
| 92 | apply_ast [MalSymbol "quasiquote", a1] env = quasiquote a1 env |
| 93 | apply_ast (MalSymbol "quasiquote" : _) _ = throwStr "invalid quasiquote" |
| 94 | |
| 95 | apply_ast [MalSymbol "defmacro!", MalSymbol a1, a2] env = do |
| 96 | func <- eval env a2 |
| 97 | case func of |
| 98 | MalFunction {macro=False} -> do |
| 99 | let m = func {macro=True} |
| 100 | liftIO $ env_set env a1 m |
| 101 | return m |
| 102 | _ -> throwStr "defmacro! on non-function" |
| 103 | apply_ast (MalSymbol "defmacro!" : _) _ = throwStr "invalid defmacro!" |
| 104 | |
| 105 | apply_ast [MalSymbol "macroexpand", a1] env = macroexpand env a1 |
| 106 | apply_ast (MalSymbol "macroexpand" : _) _ = throwStr "invalid macroexpand" |
| 107 | |
| 108 | apply_ast [MalSymbol "try*", a1] env = eval env a1 |
| 109 | apply_ast [MalSymbol "try*", a1, MalSeq _ (Vect False) [MalSymbol "catch*", MalSymbol a21, a22]] env = do |
| 110 | res <- liftIO $ runExceptT $ eval env a1 |
| 111 | case res of |
| 112 | Right val -> return val |
| 113 | Left exc -> do |
| 114 | try_env <- liftIO $ env_new env |
| 115 | liftIO $ env_set try_env a21 exc |
| 116 | eval try_env a22 |
| 117 | apply_ast (MalSymbol "try*" : _) _ = throwStr "invalid try*" |
| 118 | |
| 119 | apply_ast (MalSymbol "do" : args) env = foldlM (const $ eval env) Nil args |
| 120 | |
| 121 | apply_ast [MalSymbol "if", a1, a2, a3] env = do |
| 122 | cond <- eval env a1 |
| 123 | eval env $ case cond of |
| 124 | Nil -> a3 |
| 125 | MalBoolean False -> a3 |
| 126 | _ -> a2 |
| 127 | apply_ast [MalSymbol "if", a1, a2] env = do |
| 128 | cond <- eval env a1 |
| 129 | case cond of |
| 130 | Nil -> return Nil |
| 131 | MalBoolean False -> return Nil |
| 132 | _ -> eval env a2 |
| 133 | apply_ast (MalSymbol "if" : _) _ = throwStr "invalid if" |
| 134 | |
| 135 | apply_ast [MalSymbol "fn*", MalSeq _ _ params, ast] env = newFunction ast env <$> mapM unWrapSymbol params |
| 136 | apply_ast (MalSymbol "fn*" : _) _ = throwStr "invalid fn*" |
| 137 | |
| 138 | apply_ast ast env = do |
| 139 | evd <- mapM (eval env) ast |
| 140 | case evd of |
| 141 | MalFunction {fn=f, macro=False} : args -> f args |
| 142 | _ -> throwStr $ "invalid apply: " ++ Printer._pr_str True (toList ast) |
| 143 | |
| 144 | eval :: Env -> MalVal -> IOThrows MalVal |
| 145 | eval env ast = do |
| 146 | newAst <- macroexpand env ast |
| 147 | case newAst of |
| 148 | MalSymbol sym -> do |
| 149 | maybeVal <- liftIO $ env_get env sym |
| 150 | case maybeVal of |
| 151 | Nothing -> throwStr $ "'" ++ sym ++ "' not found" |
| 152 | Just val -> return val |
| 153 | MalSeq _ (Vect False) xs -> apply_ast xs env |
| 154 | MalSeq m (Vect True) xs -> MalSeq m (Vect True) <$> mapM (eval env) xs |
| 155 | MalHashMap m xs -> MalHashMap m <$> mapM (eval env) xs |
| 156 | _ -> return newAst |
| 157 | |
| 158 | -- print |
| 159 | |
| 160 | mal_print :: MalVal -> String |
| 161 | mal_print = Printer._pr_str True |
| 162 | |
| 163 | -- repl |
| 164 | |
| 165 | rep :: Env -> String -> IOThrows String |
| 166 | rep env line = mal_print <$> (eval env =<< mal_read line) |
| 167 | |
| 168 | repl_loop :: Env -> IO () |
| 169 | repl_loop env = do |
| 170 | line <- readline "user> " |
| 171 | case line of |
| 172 | Nothing -> return () |
| 173 | Just "" -> repl_loop env |
| 174 | Just str -> do |
| 175 | res <- runExceptT $ rep env str |
| 176 | out <- case res of |
| 177 | Left mv -> return $ "Error: " ++ Printer._pr_str True mv |
| 178 | Right val -> return val |
| 179 | putStrLn out |
| 180 | hFlush stdout |
| 181 | repl_loop env |
| 182 | |
| 183 | -- Read and evaluate a line. Ignore successful results, but crash in |
| 184 | -- case of error. This is intended for the startup procedure. |
| 185 | re :: Env -> String -> IO () |
| 186 | re repl_env line = do |
| 187 | res <- runExceptT $ eval repl_env =<< mal_read line |
| 188 | case res of |
| 189 | Left mv -> error $ "Startup failed: " ++ Printer._pr_str True mv |
| 190 | Right _ -> return () |
| 191 | |
| 192 | defBuiltIn :: Env -> (String, Fn) -> IO () |
| 193 | defBuiltIn env (sym, f) = |
| 194 | env_set env sym $ MalFunction {fn=f, f_ast=Nil, f_params=[], macro=False, meta=Nil} |
| 195 | |
| 196 | evalFn :: Env -> Fn |
| 197 | evalFn env [ast] = eval env ast |
| 198 | evalFn _ _ = throwStr "illegal call of eval" |
| 199 | |
| 200 | main :: IO () |
| 201 | main = do |
| 202 | args <- getArgs |
| 203 | load_history |
| 204 | |
| 205 | repl_env <- env_new [] |
| 206 | |
| 207 | -- core.hs: defined using Haskell |
| 208 | mapM_ (defBuiltIn repl_env) Core.ns |
| 209 | defBuiltIn repl_env ("eval", evalFn repl_env) |
| 210 | |
| 211 | -- core.mal: defined using the language itself |
| 212 | re repl_env "(def! not (fn* (a) (if a false true)))" |
| 213 | re repl_env "(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))" |
| 214 | re repl_env "(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))" |
| 215 | re repl_env "(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))" |
| 216 | |
| 217 | case args of |
| 218 | script : scriptArgs -> do |
| 219 | env_set repl_env "*ARGV*" $ toList $ MalString <$> scriptArgs |
| 220 | re repl_env $ "(load-file \"" ++ script ++ "\")" |
| 221 | [] -> do |
| 222 | env_set repl_env "*ARGV*" $ toList [] |
| 223 | repl_loop repl_env |