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 = TTSemiColon | TTBrackOpen | TTBrackClose | TTBool Bool | TTInt Int
21 | TTOp [Char] | TTIdent [Char]
26 instance toString Token where toString t = printToString t
28 lex :: [Char] -> Either [String] [Token]
30 lex ['//\n':ts] = lex ts
31 lex ['//',t:ts] = lex ['/','/':ts]
32 lex ['/**/':ts] = lex $ dropWhile ((<>)'\n') ts
33 lex ['/*',t:ts] = lex ['/','*':ts]
34 lex [';':ts] = TTSemiColon <:> lex ts
35 lex [')':ts] = TTBrackClose <:> lex ts
36 lex ['(':ts] = TTBrackOpen <:> lex ts
37 lex ['True':ts] = TTBool True <:> lex ts
38 lex ['False':ts] = TTBool False <:> lex ts
40 | isDigit t = lex [t:ts] >>= \v->case v of
41 [TTInt i:rest] = Right [TTInt (~i):rest]
46 # (d, ts) = span isDigit [t:ts]
47 = TTInt (toInt (toString d)) <:> lex ts
49 # (d, ts) = span isAlpha [t:ts]
50 = TTIdent d <:> lex ts
52 # (d, ts) = span isOp [t:ts]
54 = Left ["Unexpected: " +++ toString t +++ " ord: " +++ toString (toInt t)]
56 isOp c = isMember c ['!@#$%^&*=+/?-_|\\\'",<>.:']
58 :: Parser a :== StateT ParseState (Either [String]) a
61 , ifxs :: [((Parser Expression) -> Parser Expression, Int)]
65 pTop = getState >>= \s->case s.tokens of
66 [t:ts] = put {s & tokens=ts} >>| pure t
67 [] = liftT (Left ["Fully consumed input"])
70 pEof = getState >>= \s->case s.tokens of
72 [t:ts] = liftT (Left ["Expected EOF but got ":map toString [t:ts]])
74 (?) infixl 9 :: (Parser a) (a -> Bool) -> Parser a
75 (?) p f = p >>= \v->if (f v) (pure v) empty
77 pToken :: (Token -> Parser Token)
78 pToken = (?) pTop o (===)
80 pChainl :: (Parser (a a -> a)) (Parser a) -> Parser a
81 pChainl op p = foldl (flip ($)) <$> p <*> many (flip <$> op <*> p)
83 pChainr :: (Parser (a a -> a)) (Parser a) -> Parser a
84 pChainr op p = flip ($) <$> p <*> (flip <$> op <*> pChainr op p) <|> p
86 parse :: [Token] -> Either [String] [Function]
87 parse ts = fst <$> runStateT (reverse <$> pAST <* pEof) {tokens=ts, ifxs=[]}
89 pAST :: Parser [Function]
90 pAST = many pFunction >>= mapM \(id, args, body)->Function id args <$
91 modify (\t->{t & tokens=body}) <*> pExpression <* pEof
93 pId = (\(TTIdent i)->i) <$> pTop ? (\t->t=:(TTIdent _))
94 pOp = (\(TTOp i)->i) <$> pTop ? (\t->t=:(TTOp _))
95 pInt = (\(TTInt i)->i) <$> pTop ? (\t->t=:(TTInt _))
96 pBrack p = pToken TTBrackOpen *> p <* pToken TTBrackClose
98 pFunction :: Parser ([Char], [[Char]], [Token])
100 = (\x y z->(x, y, z))
103 <* pToken (TTOp ['='])
104 <*> many (pTop ? ((=!=)TTSemiColon))
105 <* pToken TTSemiColon
107 pFunId :: Parser [Char]
109 >>= \i->pChainr <$ pId ? ((==) ['ifxr']) <|> pChainl <$ pId ? ((==)['ifxl'])
111 >>= \s->modify (\t->{t & ifxs=[(p (App o App (Var i) <$ pOp ? ((==)i)), s):t.ifxs]})
114 pExpression :: Parser Expression
115 pExpression = getState >>= \{ifxs}->flip (foldr ($))
116 (map fst $ sortBy (on (<) snd) ifxs)
118 $ Lambda <$ pToken (TTOp ['\\']) <*> pId <* pToken (TTOp ['.']) <*> pExpression
119 <|> pBrack ( Tuple <$> pExpression <* pToken (TTOp [',']) <*> pExpression
122 <|> Lit o Int <$> pInt
123 <|> (\(TTBool i)->Lit (Bool i)) <$> pTop ? (\t->t=:(TTBool _))
124 <|> (\x->Var ['_':x]) <$ pToken (TTIdent ['code']) <*> pId