1 implementation module parse
3 import Control.Applicative
5 import Control.Monad.State
6 import Control.Monad.Trans
17 (<:>) infixl 0 :: a (m [a]) -> m [a] | Functor m
18 (<:>) l r = (\xs->[l:xs]) <$> r
20 :: Token = TTEq | TTSemiColon | TTLambda | TTDot | TTBrackOpen | TTBrackClose | TTBool Bool | TTInt Int | TTOp [Char] | TTIdent [Char]
22 lex :: [Char] -> Either [String] [Token]
24 lex [';':ts] = TTSemiColon <:> lex ts
25 lex [')':ts] = TTBrackClose <:> lex ts
26 lex ['(':ts] = TTBrackOpen <:> lex ts
27 lex ['True':ts] = TTBool True <:> lex ts
28 lex ['False':ts] = TTBool False <:> lex ts
30 | isDigit t = lex [t:ts] >>= \v->case v of
31 [TTInt i:rest] = Right [TTInt (~i):rest]
36 # (i, ts) = span isDigit [t:ts]
37 = TTInt (toInt (toString i)) <:> lex ts
39 # (i, ts) = span isAlpha [t:ts]
40 = TTIdent i <:> lex ts
42 # (i, ts) = span isOp [t:ts]
43 | i =: ['='] = TTEq <:> lex ts
44 | i =: ['.'] = TTDot <:> lex ts
45 | i =: ['\\'] = TTLambda <:> lex ts
47 = Left ["Unexpected: " +++ toString t +++ " ord: " +++ toString (toInt t)]
49 isOp c = isMember c ['!@#$%^&*=+/?-_|\\\'",<>.:']
51 :: Parser a :== StateT ParseState (Either [String]) a
54 , ifxs :: [((Parser Expression) -> Parser Expression, Int)]
58 pTop = getState >>= \s->case s.tokens of
59 [t:ts] = put {s & tokens=ts} >>| pure t
60 [] = liftT (Left ["Fully consumed input"])
63 pEof = getState >>= \s->case s.tokens of
65 [t:ts] = liftT (Left ["Expected EOF"])
67 (?) infixl 9 :: (Parser a) (a -> Bool) -> Parser a
68 (?) p f = p >>= \v->if (f v) (pure v) empty
70 pToken :: (Token -> Parser Token)
71 pToken = (?) pTop o (===)
73 pChainl :: (Parser (a a -> a)) (Parser a) -> Parser a
74 pChainl op p = foldl (flip ($)) <$> p <*> many (flip <$> op <*> p)
76 pChainr :: (Parser (a a -> a)) (Parser a) -> Parser a
77 pChainr op p = flip ($) <$> p <*> (flip <$> op <*> pChainr op p) <|> p
79 parse :: [Token] -> Either [String] [Function]
80 parse ts = fst <$> runStateT (pAST <* pEof) {tokens=ts, ifxs=[]}
82 pAST :: Parser [Function]
83 pAST = many pFunction >>= mapM \(id, args, body)->Function id args <$
84 modify (\t->{t & tokens=body}) <*> pExpression <* pEof
86 pId = (\(TTIdent i)->i) <$> pTop ? (\t->t=:(TTIdent _))
87 pOp = (\(TTOp i)->i) <$> pTop ? (\t->t=:(TTOp _))
89 pFunction :: Parser ([Char], [[Char]], [Token])
95 <*> many (pTop ? ((=!=)TTSemiColon))
98 pFunId :: Parser [Char]
100 >>= \i->pChainr <$ pId ? ((==) ['ifxr']) <|> pChainl <$ pId ? ((==)['ifxl'])
101 >>= \p->(\(TTInt i)->i) <$> pTop ? (\t->t=:(TTInt _))
102 >>= \s->modify (\t->{t & ifxs=[(p (App o App (Var i) <$ pOp ? ((==)i)), s):t.ifxs]})
105 pExpression :: Parser Expression
106 pExpression = getState >>= \{ifxs}->flip (foldr ($))
107 (map fst $ sortBy (on (<) snd) ifxs)
109 $ Lambda <$ pToken TTLambda <*> pId <* pToken TTDot <*> pExpression
110 <|> pToken TTBrackOpen *> pExpression <* pToken TTBrackClose
111 <|> Lit o Int <$> (\(TTInt i)->i) <$> pTop ? (\t->t=:(TTInt _))
112 <|> (\(TTBool i)->Lit (Bool i)) <$> pTop ? (\t->t=:(TTBool _))