-
Notifications
You must be signed in to change notification settings - Fork 0
/
io.hs
461 lines (392 loc) · 17.2 KB
/
io.hs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
{-# LANGUAGE ExistentialQuantification #-}
import Data.IORef
import System.IO
import System.Environment (getArgs)
import Control.Monad
import Control.Monad.Error
import Text.ParserCombinators.Parsec hiding (spaces)
main :: IO ()
main = do
args <- getArgs
if null args then runRepl else runOne args
-- Terminals --
symbol :: Parser Char
symbol = oneOf "!$%&|*+-/:<=>?@^_~#"
readOrThrow :: Parser a -> String -> ThrowsError a
readOrThrow parser input = case parse parser "Lisp" input of
Left err -> throwError $ Parser err
Right val -> return val
readExpr :: String -> ThrowsError LispVal
readExpr = readOrThrow parseExpr
readExprList = readOrThrow $ endBy parseExpr spaces
spaces :: Parser ()
spaces = skipMany1 space
-- Data Type definition --
data LispVal = Atom String
| List [LispVal]
| DottedList [LispVal] LispVal
| Number Integer
| String String
| Bool Bool
| Port Handle
| IOFunc ([LispVal] -> IOThrowsError LispVal)
| PrimitiveFunc ([LispVal] -> ThrowsError LispVal)
| Func { params :: [String]
, vararg :: (Maybe String)
, body :: [LispVal]
, closure :: Env
}
-- Parse Basic Type --
parseString :: Parser LispVal
parseString = do
char '\"'
x <- many $ noneOf "\""
char '\"'
return $ String x
parseAtom :: Parser LispVal
parseAtom = do
first <- letter <|> symbol
rest <- many $ letter <|> symbol <|> digit
let atom = first : rest
return $ case atom of
"#t" -> Bool True
"#f" -> Bool False
_ -> Atom atom
parseNumber :: Parser LispVal
parseNumber = liftM (Number . read) $ many1 digit
parseList :: Parser LispVal
parseList = sepBy parseExpr spaces >>= return . List
parseDottedList :: Parser LispVal
parseDottedList = do
head <- endBy parseExpr spaces
tail <- char '.' >> spaces >> parseExpr
return $ DottedList head tail
parseQuoted :: Parser LispVal
parseQuoted = do
char '\''
x <- parseExpr
return $ List [Atom "quote", x]
parseExpr :: Parser LispVal
parseExpr = parseAtom
<|> parseString
<|> parseNumber
<|> parseQuoted
<|> do char '('
x <- try parseList <|> parseDottedList
char ')'
return x
showVal :: LispVal -> String
showVal (Atom name) = name
showVal (List xs) = "(" ++ unwordsList xs ++ ")"
showVal (DottedList init last) = "(" ++ unwordsList init ++ " . " ++ show last ++ ")"
showVal (Number num) = show num
showVal (String str) = "\"" ++ str ++ "\""
showVal (Bool b) = if b then "#t" else "#f"
showVal (Port _) = "<IO port>"
showVal (IOFunc _) = "<IO primitive>"
showVal (PrimitiveFunc _) = "<primitive>"
showVal (Func {params = args, vararg = varargs, body = body, closure = env}) =
"(lambda (" ++ unwords (map show args) ++
(case varargs of
Nothing -> ""
Just arg -> " . " ++ arg) ++ ") ...)"
unwordsList :: [LispVal] -> String
unwordsList = unwords . map showVal
instance Show LispVal where show = showVal
-- Eval varoius forms --
eval :: Env -> LispVal -> IOThrowsError LispVal
eval env val@(String _) = return val
eval env val@(Number _) = return val
eval env val@(Bool _) = return val
eval env (Atom id) = getVar env id
eval env (List [Atom "quote", val]) = return val
eval env (List [Atom "load", String filename]) =
load filename >>= liftM last . mapM (eval env)
eval env form@(List (Atom "cond" : xs)) = evalCond xs
where evalCond [] = throwError $ BadSpecialForm "cond里冇为真的表达式" form
evalCond (List (Atom "else" : vals) : _) = mapM (eval env) vals >>= return . last
evalCond (List (cond : vals) : rest) = do
result <- eval env cond
case result of
Bool False -> evalCond rest
Bool True -> mapM (eval env) vals >>= return . last
otherwise -> throwError $ TypeMismatch "boolean" cond
eval env form@(List (Atom "case" : key : xs)) = do
evaledKey <- eval env key
resultList <- evalCase evaledKey xs
return $ last resultList
where evalCase k [] = throwError $ BadSpecialForm "No matched list in case" form
evalCase k (List (Atom "else" : vals) : _) = mapM (eval env) vals
evalCase k (List (List datums : vals) : rest) = do
equalities <- mapM (\x -> liftThrows $ eqv [k, x]) datums
if any (\(Bool b) -> b) equalities
then mapM (eval env) vals
else evalCase k rest
evalCase k xs = throwError $ BadSpecialForm "Bad case" $ List xs
eval env (List [Atom "if", pred, stmt1, stmt2]) = do
result <- eval env pred
eval env $ case result of {Bool False -> stmt2; _ -> stmt1}
eval env (List [Atom "set!", Atom var, form]) = eval env form >>= setVar env var
eval env (List [Atom "define", Atom var, form]) = eval env form >>= defineVar env var
eval env (List (Atom "define" : List (Atom var : params) : body)) =
makeNormalFunc env params body >>= defineVar env var
eval env (List (Atom "define" : DottedList (Atom var : params) varargs : body)) =
makeVarArgs varargs env params body >>= defineVar env var
eval env (List (Atom "lambda" : List params : body)) =
makeNormalFunc env params body
eval env (List (Atom "lambda" : DottedList params varargs : body)) =
makeVarArgs varargs env params body
eval env (List (Atom "lambda" : varargs@(Atom _) : body)) =
makeVarArgs varargs env [] body
eval env (List (function : args)) = do
func <- eval env function
argVals <- mapM (eval env) args
apply func argVals
eval env badForm = throwError $ BadSpecialForm "识唔得此形式" badForm
apply :: LispVal -> [LispVal] -> IOThrowsError LispVal
apply (IOFunc func) args = func args
apply (PrimitiveFunc func) args = liftThrows $ func args
apply (Func params varargs body closure) args =
if num params /= num args && varargs == Nothing
then throwError $ NumArgs (num params) args
else (liftIO . bindVars closure $ zip params args) >>= bindVarArgs varargs >>= evalBody
where num = toInteger . length
restArgs = drop (length params) args
evalBody env = liftM last $ mapM (eval env) body
bindVarArgs arg env = case arg of
Just argName -> liftIO $ bindVars env [(argName, List restArgs)]
Nothing -> return env
primeBindings :: IO Env
primeBindings = nullEnv >>= flip bindVars (map (makeFunc IOFunc) ioPrimitives
++ map (makeFunc PrimitiveFunc) primitives)
where makeFunc funcType (var, func) = (var, funcType func)
primitives :: [(String, [LispVal] -> ThrowsError LispVal)]
primitives = [("+", numericBinop (+)),
("-", numericBinop (-)),
("*", numericBinop (*)),
("/", numericBinop div),
("mod", numericBinop mod),
("quotient", numericBinop quot),
("remainder", numericBinop rem),
("=", numBoolBinop (==)),
("<", numBoolBinop (<)),
(">", numBoolBinop (>)),
("/=", numBoolBinop (/=)),
(">=", numBoolBinop (>=)),
("<=", numBoolBinop (<=)),
("&&", boolBoolBinop (&&)),
("||", boolBoolBinop (||)),
("string=?", strBoolBinop (==)),
("string<?", strBoolBinop (<)),
("string>?", strBoolBinop (>)),
("string<=?", strBoolBinop (<=)),
("string>=?", strBoolBinop (>=)),
("car", car),
("cdr", cdr),
("cons", cons),
("eq?", eqv),
("eqv?", eqv),
("equal?", equal)]
ioPrimitives :: [(String, [LispVal] -> IOThrowsError LispVal)]
ioPrimitives = [("apply", applyProc),
("open-input-file", makePort ReadMode),
("open-output-file", makePort WriteMode),
("close-input-port", closePort),
("close-output-port", closePort),
("read", readProc),
("write", writeProc),
("read-contents", readContents),
("read-all", readAll)]
applyProc :: [LispVal] -> IOThrowsError LispVal
applyProc [func, List args] = apply func args
applyProc (func : args) = apply func args
makePort :: IOMode -> [LispVal] -> IOThrowsError LispVal
makePort mode [String filename] = liftM Port . liftIO $ openFile filename mode
closePort :: [LispVal] -> IOThrowsError LispVal
closePort [Port port] = liftIO $ hClose port >> return (Bool True)
closePort _ = return $ Bool False
readProc :: [LispVal] -> IOThrowsError LispVal
readProc [] = readProc [Port stdin]
readProc [Port port] = liftIO (hGetLine port) >>= liftThrows . readExpr
writeProc :: [LispVal] -> IOThrowsError LispVal
writeProc [obj] = writeProc [obj, Port stdout]
writeProc [obj, Port port] = liftIO $ hPrint port obj >> return (Bool True)
readContents :: [LispVal] -> IOThrowsError LispVal
readContents [String filename] = liftM String . liftIO $ readFile filename
load :: String -> IOThrowsError [LispVal]
load filename = liftIO (readFile filename) >>= liftThrows . readExprList
readAll :: [LispVal] -> IOThrowsError LispVal
readAll [String filename] = liftM List $ load filename
boolBinop :: (LispVal -> ThrowsError a) -> (a -> a -> Bool) -> [LispVal] -> ThrowsError LispVal
boolBinop unpacker op args = if length args /= 2
then throwError $ NumArgs 2 args
else do left <- unpacker $ args !! 0
right <- unpacker $ args !! 1
return $ Bool $ left `op` right
numericBinop :: (Integer -> Integer -> Integer) -> [LispVal] -> ThrowsError LispVal
numericBinop op [] = throwError $ NumArgs 2 []
numericBinop op singleVal@[_] = throwError $ NumArgs 2 singleVal
numericBinop op params = mapM unpackNum params >>= return . Number . foldl1 op
numBoolBinop = boolBinop unpackNum
strBoolBinop = boolBinop unpackStr
boolBoolBinop = boolBinop unpackBool
unpackNum :: LispVal -> ThrowsError Integer
unpackNum (Number n) = return n
unpackNum (String n) = let parsed = reads n in
if null parsed
then throwError . TypeMismatch "number" $ String n
else return . fst $ head parsed
unpackNum (List [n]) = unpackNum n
unpackNum notNum = throwError $ TypeMismatch "number" notNum
unpackStr :: LispVal -> ThrowsError String
unpackStr (String s) = return s
unpackStr (Number s) = return $ show s
unpackStr (Bool s) = return $ show s
unpackStr notString = throwError $ TypeMismatch "string" notString
unpackBool :: LispVal -> ThrowsError Bool
unpackBool (Bool b) = return b
unpackBool notBool = throwError $ TypeMismatch "boolean" notBool
car :: [LispVal] -> ThrowsError LispVal
car [List (x : _)] = return x
car [DottedList (x : _) _] = return x
car [badArg] = throwError $ TypeMismatch "pair" badArg
car badArgList = throwError $ NumArgs 1 badArgList
cdr :: [LispVal] -> ThrowsError LispVal
cdr [List (_ : xs)] = return $ List xs
cdr [DottedList [_] x] = return x
cdr [DottedList (_ : xs) x] = return $ DottedList xs x
cdr [badArg] = throwError $ TypeMismatch "pair" badArg
cdr badArgList = throwError $ NumArgs 1 badArgList
cons :: [LispVal] -> ThrowsError LispVal
cons [x, List xs] = return . List $ x : xs
cons [x, DottedList xs xlast] = return $ DottedList (x : xs) xlast
cons [x1, x2] = return $ DottedList [x1] x2
cons badArgList = throwError $ NumArgs 2 badArgList
eqv :: [LispVal] -> ThrowsError LispVal
eqv [(Bool x), (Bool y)] = return . Bool $ x == y
eqv [(Number x), (Number y)] = return . Bool $ x == y
eqv [(String x), (String y)] = return . Bool $ x == y
eqv [(Atom x), (Atom y)] = return . Bool $ x == y
eqv [(DottedList xs x), (DottedList ys y)] = eqv [List $ xs ++ [x], List $ ys ++ [y]]
eqv [x@(List _), y@(List _)] = eqvList eqv [x, y]
eqv [_, _] = return $ Bool False
eqv badArgList = throwError $ NumArgs 2 badArgList
data Unpacker = forall a. Eq a => AnyUnpacker (LispVal -> ThrowsError a)
unpackEquals :: LispVal -> LispVal -> Unpacker -> ThrowsError Bool
unpackEquals x y (AnyUnpacker unpacker) = do
x' <- unpacker x
y' <- unpacker y
return $ x' == y'
`catchError` (const $ return False)
equal :: [LispVal] -> ThrowsError LispVal
equal [x@(List _), y@(List _)] = eqvList equal [x, y]
equal [(DottedList xs x), (DottedList ys y)] = equal [List $ xs ++ [x], List $ ys ++ [y]]
equal [x, y] = do
primitiveEquals <- liftM or $ mapM (unpackEquals x y) [AnyUnpacker unpackNum,
AnyUnpacker unpackStr,
AnyUnpacker unpackBool]
eqvEquals <- eqv [x, y]
return . Bool $ primitiveEquals || let (Bool x) = eqvEquals in x
equal badArgList = throwError $ NumArgs 2 badArgList
eqvList :: ([LispVal] -> ThrowsError LispVal) -> [LispVal] -> ThrowsError LispVal
eqvList eqFunc [(List x), (List y)] =
return . Bool $ (length x == length y) && (all eqvPair $ zip x y)
where eqvPair (a, b) = case eqFunc [a, b] of
Left error -> False
Right (Bool v)-> v
data LispError = NumArgs Integer [LispVal]
| TypeMismatch String LispVal
| Parser ParseError
| BadSpecialForm String LispVal
| NotFunction String String
| UnboundVar String String
| Default String
showError :: LispError -> String
showError (UnboundVar message varname) = message ++ ": " ++ varname
showError (BadSpecialForm message form) = message ++ ": " ++ show form
showError (NotFunction message func) = message ++ ": " ++ show func
showError (TypeMismatch expected found) = "错误类型: 期望" ++ expected ++ ", 实参:" ++ show found
showError (Parser parseErr) = "解析错误,位置: " ++ show parseErr
instance Show LispError where show = showError
instance Error LispError where
noMsg = Default "I'm angry...出现了错误"
strMsg = Default
type ThrowsError = Either LispError
trapError :: IOThrowsError String -> IOThrowsError String
trapError action = catchError action $ return . show
extractValue :: ThrowsError a -> a
extractValue (Right val) = val
-- for REPL --
flushStr :: String -> IO ()
flushStr str = putStr str >> hFlush stdout
readPrompt :: String -> IO (Maybe String)
readPrompt prompt = do
flushStr prompt
end <- isEOF
if end
then return Nothing
else do str <- getLine
return $ if str == "quit" then Nothing else Just str
evalString :: Env -> String -> IO String
evalString env expr =
runIOThrows . liftM show $ liftThrows (readExpr expr) >>= eval env
evalAndPrint :: Env -> String -> IO ()
evalAndPrint env expr = evalString env expr >>= putStrLn
until_ :: Monad m => m (Maybe a) -> m () -> (a -> m ()) -> m ()
until_ prompt end body = do
result <- prompt
case result of
Nothing -> end
Just s -> body s >> until_ prompt end body
runOne :: [String] -> IO ()
runOne args = do
env <- primeBindings >>= flip bindVars [("args", List . map String $ tail args)]
err <- runIOThrows . liftM show . eval env $ List [Atom "load", String $ head args]
hPutStrLn stderr err
runRepl :: IO ()
runRepl = primeBindings >>= until_ (readPrompt "吼啊-> ")
(putStrLn "蛤??? 这么快就跑了?") . evalAndPrint
-- IORef --
type Env = IORef [(String, IORef LispVal)]
nullEnv :: IO Env
nullEnv = newIORef []
type IOThrowsError = ErrorT LispError IO
liftThrows :: ThrowsError a -> IOThrowsError a
liftThrows (Left err) = throwError err
liftThrows (Right val) = return val
runIOThrows :: IOThrowsError String -> IO String
runIOThrows action = runErrorT (trapError action) >>= return . extractValue
isBound :: Env -> String -> IO Bool
isBound envRef key =
readIORef envRef >>= return . maybe False (const True) . lookup key
getVar :: Env -> String -> IOThrowsError LispVal
getVar envRef key = do
env <- liftIO $ readIORef envRef
maybe (throwError $ UnboundVar "仄个变量没听说过" key)
(liftIO . readIORef)
(lookup key env)
setVar :: Env -> String -> LispVal -> IOThrowsError LispVal
setVar envRef key val = do
env <- liftIO $ readIORef envRef
maybe (throwError $ UnboundVar "设置子虚乌有的变量" key)
(liftIO . flip writeIORef val)
(lookup key env)
return val
defineVar :: Env -> String -> LispVal -> IOThrowsError LispVal
defineVar envRef key val = do
alreadyDefined <- liftIO $ isBound envRef key
if alreadyDefined
then setVar envRef key val >> return val
else liftIO $ do
valRef <- newIORef val
oldEnv <- readIORef envRef
writeIORef envRef $ (key, valRef) : oldEnv
return val
bindVars :: Env -> [(String, LispVal)] -> IO Env
bindVars envRef pairs = readIORef envRef >>= extendEnv pairs >>= newIORef
where extendEnv pairs env = liftM (++ env) $ mapM addBinding pairs
addBinding (k, v) = newIORef v >>= \ref -> return (k, ref)
makeFunc varargs env params body =
return $ Func (map showVal params) varargs body env
makeNormalFunc = makeFunc Nothing
makeVarArgs = makeFunc . Just . showVal