megaparsec/Text/Megaparsec/Prim.hs

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-- |
-- Module : Text.Megaparsec.Prim
-- Copyright : © 2015 Megaparsec contributors
-- © 2007 Paolo Martini
-- © 19992001 Daan Leijen
-- License : BSD3
--
-- Maintainer : Mark Karpov <markkarpov@opmbx.org>
-- Stability : experimental
-- Portability : portable
--
-- The primitive parser combinators.
{-# OPTIONS_HADDOCK not-home #-}
module Text.Megaparsec.Prim
( State (..)
, Stream (..)
, Consumed (..)
, Reply (..)
, ParsecT
, Parsec
, runParsecT
, mkPT
, unknownError
, sysUnExpectError
, unexpected
, mergeErrorReply
, (<?>)
, label
, runParserT
, runParser
, parse
, parseMaybe
, parseTest
, try
, lookAhead
, token
, tokens
, tokenPrim
, skipMany
, getPosition
, getInput
, setPosition
, setInput
, getParserState
, setParserState
, updateParserState
, getState
, putState
, modifyState )
where
import qualified Data.ByteString.Char8 as C
import qualified Data.ByteString.Lazy.Char8 as CL
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
import Control.Monad
import Control.Monad.Identity
import Control.Monad.Trans
import Control.Monad.Reader.Class
import Control.Monad.State.Class hiding (state)
import Control.Monad.Cont.Class
import Control.Monad.Error.Class
import qualified Control.Applicative as A
import Text.Megaparsec.Pos
import Text.Megaparsec.Error
-- | This is Parsec state, this is parametrized over stream type @s@, and
-- user state @u@.
data State s u = State
{ stateInput :: s
, statePos :: !SourcePos
, stateUser :: !u }
-- | An instance of @Stream s m t@ has stream type @s@, underlying monad @m@
-- and token type @t@ determined by the stream.
--
-- Some rough guidelines for a \"correct\" instance of Stream:
--
-- * unfoldM uncons gives the [t] corresponding to the stream
--
-- * A @Stream@ instance is responsible for maintaining the \"position
-- within the stream\" in the stream state @s@. This is trivial unless
-- you are using the monad in a non-trivial way.
class Monad m => Stream s m t | s -> t where
uncons :: s -> m (Maybe (t, s))
instance Monad m => Stream [tok] m tok where
uncons [] = return Nothing
uncons (t:ts) = return $ Just (t, ts)
{-# INLINE uncons #-}
instance Monad m => Stream CL.ByteString m Char where
uncons = return . CL.uncons
instance Monad m => Stream C.ByteString m Char where
uncons = return . C.uncons
instance Monad m => Stream T.Text m Char where
uncons = return . T.uncons
{-# INLINE uncons #-}
instance Monad m => Stream TL.Text m Char where
uncons = return . TL.uncons
{-# INLINE uncons #-}
-- | This data structure represents an aspect of result of parser's
-- work. The two constructors have the following meaning:
--
-- * @Cosumed@ is a wrapper for result when some part of input stream
-- was consumed.
--
-- * @Empty@ is a wrapper for result when input stream is empty.
--
-- You shouldn't really need to know this. See also: 'Reply'.
data Consumed a = Consumed a
| Empty !a
instance Functor Consumed where
fmap f (Consumed x) = Consumed (f x)
fmap f (Empty x) = Empty (f x)
-- | This data structure represents an aspect of result of parser's
-- work. The two constructors have the following meaning:
--
-- * @Ok@ for successfully run parser.
-- * @Error@ for failed parser.
--
-- You shouldn't really need to know this. See also 'Consumed'.
data Reply s u a = Ok a !(State s u) ParseError
| Error ParseError
instance Functor (Reply s u) where
fmap f (Ok x s e) = Ok (f x) s e
fmap _ (Error e) = Error e
-- | @ParsecT s u m a@ is a parser with stream type @s@, user state type @u@,
-- underlying monad @m@ and return type @a@. Parsec is strict in the user
-- state. If this is undesirable, simply use a data type like @data Box a =
-- Box a@ and the state type @Box YourStateType@ to add a level of
-- indirection.
newtype ParsecT s u m a = ParsecT
{ unParser :: forall b . State s u
-> (a -> State s u -> ParseError -> m b) -- consumed ok
-> (ParseError -> m b) -- consumed err
-> (a -> State s u -> ParseError -> m b) -- empty ok
-> (ParseError -> m b) -- empty err
-> m b }
-- | @Parsec@ is non-transformer variant of more general @ParsecT@
-- monad-transformer.
type Parsec s u = ParsecT s u Identity
instance Functor (ParsecT s u m) where
fmap = parsecMap
parsecMap :: (a -> b) -> ParsecT s u m a -> ParsecT s u m b
parsecMap f p = ParsecT $ \s cok cerr eok eerr ->
unParser p s (cok . f) cerr (eok . f) eerr
instance A.Applicative (ParsecT s u m) where
pure = return
(<*>) = ap -- TODO: Can this be optimized?
(*>) = (>>)
p1 <* p2 = do { x1 <- p1 ; void p2 ; return x1 }
instance A.Alternative (ParsecT s u m) where
empty = mzero
(<|>) = mplus
many p = reverse <$> manyAccum (:) p
instance Monad (ParsecT s u m) where
return = parserReturn
(>>=) = parserBind
fail = parserFail
parserReturn :: a -> ParsecT s u m a
parserReturn x = ParsecT $ \s _ _ eok _ -> eok x s (unknownError s)
parserBind :: ParsecT s u m a -> (a -> ParsecT s u m b) -> ParsecT s u m b
{-# INLINE parserBind #-}
parserBind m k = ParsecT $ \s cok cerr eok eerr ->
let
-- consumed-okay case for m
mcok x st err =
let
-- if (k x) consumes, those go straight up
pcok = cok
pcerr = cerr
-- if (k x) doesn't consume input, but is okay, we still
-- return in the consumed continuation
peok x' s' err' = cok x' s' (mergeError err err')
-- if (k x) doesn't consume input, but errors, we return the
-- error in the 'consumed-error' continuation
peerr err' = cerr (mergeError err err')
in unParser (k x) st pcok pcerr peok peerr
-- empty-ok case for m
meok x st err =
let
-- in these cases, (k x) can return as empty
pcok = cok
peok x' s' err' = eok x' s' (mergeError err err')
pcerr = cerr
peerr err' = eerr (mergeError err err')
in unParser (k x) st pcok pcerr peok peerr
-- consumed-error case for m
mcerr = cerr
-- empty-error case for m
meerr = eerr
in unParser m s mcok mcerr meok meerr
parserFail :: String -> ParsecT s u m a
parserFail msg = ParsecT $ \s _ _ _ eerr ->
eerr $ newErrorMessage (Message msg) (statePos s)
-- | Low-level unpacking of the ParsecT type. To run your parser, please look to
-- 'runPT', 'runP', 'runParserT', 'runParser' and other such functions.
runParsecT :: Monad m =>
ParsecT s u m a -> State s u -> m (Consumed (m (Reply s u a)))
runParsecT p s = unParser p s cok cerr eok eerr
where cok a s' err = return . Consumed . return $ Ok a s' err
cerr err = return . Consumed . return $ Error err
eok a s' err = return . Empty . return $ Ok a s' err
eerr err = return . Empty . return $ Error err
-- | Low-level creation of the ParsecT type. You really shouldn't have to do
-- this.
mkPT :: Monad m =>
(State s u -> m (Consumed (m (Reply s u a)))) -> ParsecT s u m a
mkPT k = ParsecT $ \s cok cerr eok eerr -> do
cons <- k s
case cons of
Consumed mrep -> do
rep <- mrep
case rep of
Ok x s' err -> cok x s' err
Error err -> cerr err
Empty mrep -> do
rep <- mrep
case rep of
Ok x s' err -> eok x s' err
Error err -> eerr err
instance MonadIO m => MonadIO (ParsecT s u m) where
liftIO = lift . liftIO
instance MonadReader r m => MonadReader r (ParsecT s u m) where
ask = lift ask
local f p = mkPT $ \s -> local f (runParsecT p s)
-- I'm presuming the user might want a separate, non-backtracking state
-- aside from the Parsec user state.
instance MonadState s m => MonadState s (ParsecT s' u m) where
get = lift get
put = lift . put
instance MonadCont m => MonadCont (ParsecT s u m) where
callCC f = mkPT $ \s ->
callCC $ \c ->
runParsecT (f (\a -> mkPT $ \s' -> c (pack s' a))) s
where pack s a= Empty $ return (Ok a s (unknownError s))
instance MonadError e m => MonadError e (ParsecT s u m) where
throwError = lift . throwError
p `catchError` h = mkPT $ \s ->
runParsecT p s `catchError` \e ->
runParsecT (h e) s
instance MonadPlus (ParsecT s u m) where
mzero = parserZero
mplus = parserPlus
parserZero :: ParsecT s u m a
parserZero = ParsecT $ \s _ _ _ eerr -> eerr $ unknownError s
parserPlus :: ParsecT s u m a -> ParsecT s u m a -> ParsecT s u m a
{-# INLINE parserPlus #-}
parserPlus m n
= ParsecT $ \s cok cerr eok eerr ->
let
meerr err =
let
neok y s' err' = eok y s' (mergeError err err')
neerr err' = eerr $ mergeError err err'
in unParser n s cok cerr neok neerr
in unParser m s cok cerr eok meerr
instance MonadTrans (ParsecT s u) where
lift amb = ParsecT $ \s _ _ eok _ -> do
a <- amb
eok a s $ unknownError s
-- Errors
-- | Create new @ParseError@ object. It will contain information about
-- position at which error is happened and nothing more.
unknownError :: State s u -> ParseError
unknownError state = newErrorUnknown (statePos state)
-- | @sysUnExpectError m pos@ creates 'Reply' that represents \"unexpected\"
-- error with associated message @m@ and position @pos@.
sysUnExpectError :: String -> SourcePos -> Reply s u a
sysUnExpectError msg pos = Error (newErrorMessage (SysUnExpect msg) pos)
-- | The parser @unexpected msg@ always fails with an unexpected error
-- message @msg@ without consuming any input.
--
-- The parsers 'fail', ('<?>') and @unexpected@ are the three parsers used
-- to generate error messages. Of these, only ('<?>') is commonly used. For
-- an example of the use of @unexpected@, see the definition of
-- 'Text.Megaparsec.Combinator.notFollowedBy'.
unexpected :: Stream s m t => String -> ParsecT s u m a
unexpected msg = ParsecT $ \s _ _ _ eerr ->
eerr $ newErrorMessage (UnExpect msg) (statePos s)
-- | @mergeErrorReply e reply@ returns @reply@ with error @e@ added.
mergeErrorReply :: ParseError -> Reply s u a -> Reply s u a
mergeErrorReply err1 reply
= case reply of
Ok x state err2 -> Ok x state (mergeError err1 err2)
Error err2 -> Error (mergeError err1 err2)
-- Basic combinators
infix 0 <?>
-- | The parser @p \<?> msg@ behaves as parser @p@, but whenever the
-- parser @p@ fails /without consuming any input/, it replaces expect error
-- messages with the expect error message @msg@.
--
-- This is normally used at the end of a set alternatives where we want to
-- return an error message in terms of a higher level construct rather than
-- returning all possible characters. For example, if the @expr@ parser from
-- the 'try' example would fail, the error message is: '…: expecting
-- expression'. Without the @(\<?>)@ combinator, the message would be like
-- '…: expecting \"let\" or letter', which is less friendly.
(<?>) :: ParsecT s u m a -> String -> ParsecT s u m a
p <?> msg = label p msg
-- | A synonym for @\<?>@, but as a function instead of an operator.
label :: ParsecT s u m a -> String -> ParsecT s u m a
label p msg = labels p [msg]
labels :: ParsecT s u m a -> [String] -> ParsecT s u m a
labels p msgs = ParsecT $ \s cok cerr eok eerr ->
let eok' x s' error' = eok x s' $ if errorIsUnknown error'
then error'
else setExpectErrors error' msgs
eerr' err = eerr $ setExpectErrors err msgs
in unParser p s cok cerr eok' eerr'
where
setExpectErrors err [] = setErrorMessage (Expect "") err
setExpectErrors err [m] = setErrorMessage (Expect m) err
setExpectErrors err (m:ms)
= foldr (\msg' err' -> addErrorMessage (Expect msg') err')
(setErrorMessage (Expect m) err) ms
-- Running a parser
-- | The most general way to run a parser. @runParserT p state filePath
-- input@ runs parser @p@ on the input list of tokens @input@, obtained from
-- source @filePath@ with the initial user state @st@. The @filePath@ is
-- only used in error messages and may be the empty string. Returns a
-- computation in the underlying monad @m@ that return either a 'ParseError'
-- ('Left') or a value of type @a@ ('Right').
runParserT :: Stream s m t =>
ParsecT s u m a -> u -> SourceName -> s -> m (Either ParseError a)
runParserT p u name s
= do res <- runParsecT p (State s (initialPos name) u)
r <- parserReply res
case r of
Ok x _ _ -> return (Right x)
Error err -> return (Left err)
where parserReply res
= case res of
Consumed r -> r
Empty r -> r
-- | The most general way to run a parser over the Identity
-- monad. @runParser p state filePath input@ runs parser @p@ on the input
-- list of tokens @input@, obtained from source @filePath@ with the initial
-- user state @st@. The @filePath@ is only used in error messages and may
-- be the empty string. Returns either a 'ParseError' ('Left') or a value of
-- type @a@ ('Right').
--
-- > parseFromFile p fname = runParser p () fname <$> readFile fname
runParser :: Stream s Identity t =>
Parsec s u a -> u -> SourceName -> s -> Either ParseError a
runParser p u name s = runIdentity $ runParserT p u name s
-- | @parse p filePath input@ runs a parser @p@ over Identity without user
-- state. The @filePath@ is only used in error messages and may be the empty
-- string. Returns either a 'ParseError' ('Left') or a value of type @a@
-- ('Right').
--
-- > main = case (parse numbers "" "11, 2, 43") of
-- > Left err -> print err
-- > Right xs -> print (sum xs)
-- >
-- > numbers = commaSep integer
parse :: Stream s Identity t =>
Parsec s () a -> SourceName -> s -> Either ParseError a
parse p = runParser p ()
-- | @parseMaybe p input@ runs parser @p@ on @input@ and returns result
-- inside @Just@ on success and @Nothing@ on failure.
parseMaybe :: Stream s Identity t => Parsec s () a -> s -> Maybe a
parseMaybe p s =
case parse p "" s of
Left _ -> Nothing
Right x -> Just x
-- | The expression @parseTest p input@ applies a parser @p@ against
-- input @input@ and prints the result to stdout. Used for testing.
parseTest :: (Stream s Identity t, Show a) => Parsec s () a -> s -> IO ()
parseTest p input =
case parse p "" input of
Left err -> putStr "parse error at " >> print err
Right x -> print x
-- | The parser @try p@ behaves like parser @p@, except that it
-- pretends that it hasn't consumed any input when an error occurs.
--
-- This combinator is used whenever arbitrary look ahead is needed. Since it
-- pretends that it hasn't consumed any input when @p@ fails, the ('<|>')
-- combinator will try its second alternative even when the first parser
-- failed while consuming input.
--
-- The @try@ combinator can for example be used to distinguish identifiers
-- and reserved words. Both reserved words and identifiers are a sequence of
-- letters. Whenever we expect a certain reserved word where we can also
-- expect an identifier we have to use the @try@ combinator. Suppose we
-- write:
--
-- > expr = letExpr <|> identifier <?> "expression"
-- >
-- > letExpr = string "let" >> …
-- > identifier = some letter
--
-- If the user writes \"lexical\", the parser fails with: @unexpected \'x\',
-- expecting \'t\' in \"let\"@. Indeed, since the ('<|>') combinator only
-- tries alternatives when the first alternative hasn't consumed input, the
-- @identifier@ parser is never tried (because the prefix \"le\" of the
-- @string \"let\"@ parser is already consumed). The right behaviour can be
-- obtained by adding the @try@ combinator:
--
-- > expr = letExpr <|> identifier <?> "expression"
-- >
-- > letExpr = try (string "let") >> …
-- > identifier = some letter
try :: ParsecT s u m a -> ParsecT s u m a
try p = ParsecT $ \s cok _ eok eerr -> unParser p s cok eerr eok eerr
-- | @lookAhead p@ parses @p@ without consuming any input.
--
-- If @p@ fails and consumes some input, so does @lookAhead@. Combine with
-- 'try' if this is undesirable.
lookAhead :: (Stream s m t) => ParsecT s u m a -> ParsecT s u m a
lookAhead p = ParsecT $ \s _ cerr eok eerr -> do
let eok' a _ _ = eok a s (newErrorUnknown (statePos s))
unParser p s eok' cerr eok' eerr
-- | The parser @token showTok posFromTok testTok@ accepts a token @t@
-- with result @x@ when the function @testTok t@ returns @'Just' x@. The
-- source position of the @t@ should be returned by @posFromTok t@ and the
-- token can be shown using @showTok t@.
--
-- This combinator is expressed in terms of 'tokenPrim'. It is used to
-- accept user defined token streams. For example, suppose that we have a
-- stream of basic tokens tupled with source positions. We can than define a
-- parser that accepts single tokens as:
--
-- > mytoken x = token showTok posFromTok testTok
-- > where
-- > showTok (pos,t) = show t
-- > posFromTok (pos,t) = pos
-- > testTok (pos,t) = if x == t then Just t else Nothing
token :: Stream s Identity t =>
(t -> String) -- ^ Token pretty-printing function.
-> (t -> SourcePos) -- ^ Computes the position of a token.
-> (t -> Maybe a) -- ^ Matching function for the token to parse.
-> Parsec s u a
token showToken tokpos = tokenPrim showToken nextpos
where nextpos _ tok ts =
case runIdentity (uncons ts) of
Nothing -> tokpos tok
Just (tok', _) -> tokpos tok'
-- | The parser @tokens showToks posFromTok@ parses list of tokens and
-- returns it. The resulting parser will use @showToks@ to pretty-print the
-- collection of tokens.
--
-- This can be used to example to write 'Text.Megaparsec.Char.string':
--
-- > string = tokens show updatePosString
tokens :: (Stream s m t, Eq t) =>
([t] -> String) -- ^ Pretty print a list of tokens
-> (SourcePos -> [t] -> SourcePos) -- ^ Computes position of tokens.
-> [t] -- ^ List of tokens to parse
-> ParsecT s u m [t]
{-# INLINE tokens #-}
tokens _ _ []
= ParsecT $ \s _ _ eok _ ->
eok [] s $ unknownError s
tokens showTokens nextposs tts@(tok:toks)
= ParsecT $ \(State input pos u) cok cerr _ eerr ->
let
errEof = setErrorMessage (Expect (showTokens tts))
(newErrorMessage (SysUnExpect "") pos)
errExpect x = setErrorMessage (Expect (showTokens tts))
(newErrorMessage (SysUnExpect (showTokens [x])) pos)
walk [] rs = ok rs
walk (t:ts) rs = do
sr <- uncons rs
case sr of
Nothing -> cerr errEof
Just (x,xs)
| t == x -> walk ts xs
| otherwise -> cerr $ errExpect x
ok rs = let pos' = nextposs pos tts
s' = State rs pos' u
in cok tts s' (newErrorUnknown pos')
in do
sr <- uncons input
case sr of
Nothing -> eerr errEof
Just (x,xs)
| tok == x -> walk toks xs
| otherwise -> eerr $ errExpect x
-- | The parser @tokenPrim showTok nextPos testTok@ accepts a token @t@
-- with result @x@ when the function @testTok t@ returns @'Just' x@. The
-- token can be shown using @showTok t@. The position of the /next/ token
-- should be returned when @nextPos@ is called with the current source
-- position @pos@, the current token @t@ and the rest of the tokens @toks@,
-- @nextPos pos t toks@.
--
-- This is the most primitive combinator for accepting tokens. For example,
-- the 'Text.Megaparsec.Char.char' parser could be implemented as:
--
-- > char c = tokenPrim showChar nextPos testChar
-- > where showChar x = "'" ++ x ++ "'"
-- > testChar x = if x == c then Just x else Nothing
-- > nextPos pos x xs = updatePosChar pos x
tokenPrim :: Stream s m t =>
(t -> String) -- ^ Token pretty-printing function.
-> (SourcePos -> t -> s -> SourcePos) -- ^ Next position calculating function.
-> (t -> Maybe a) -- ^ Matching function for the token to parse.
-> ParsecT s u m a
{-# INLINE tokenPrim #-}
tokenPrim showToken nextpos = tokenPrimEx showToken nextpos Nothing
tokenPrimEx :: Stream s m t
=> (t -> String)
-> (SourcePos -> t -> s -> SourcePos)
-> Maybe (SourcePos -> t -> s -> u -> u)
-> (t -> Maybe a)
-> ParsecT s u m a
{-# INLINE tokenPrimEx #-}
tokenPrimEx showToken nextpos Nothing test
= ParsecT $ \(State input pos user) cok _ _ eerr -> do
r <- uncons input
case r of
Nothing -> eerr $ unexpectError "" pos
Just (c,cs)
-> case test c of
Just x -> let newpos = nextpos pos c cs
newstate = State cs newpos user
in seq newpos $ seq newstate $
cok x newstate (newErrorUnknown newpos)
Nothing -> eerr $ unexpectError (showToken c) pos
tokenPrimEx showToken nextpos (Just nextState) test
= ParsecT $ \(State input pos user) cok _ _ eerr -> do
r <- uncons input
case r of
Nothing -> eerr $ unexpectError "" pos
Just (c,cs)
-> case test c of
Just x -> let newpos = nextpos pos c cs
newUser = nextState pos c cs user
newstate = State cs newpos newUser
in seq newpos $ seq newstate $
cok x newstate $ newErrorUnknown newpos
Nothing -> eerr $ unexpectError (showToken c) pos
unexpectError :: String -> SourcePos -> ParseError
unexpectError msg = newErrorMessage (SysUnExpect msg)
-- | @skipMany p@ applies the parser @p@ /zero/ or more times, skipping
-- its result.
--
-- > spaces = skipMany space
skipMany :: ParsecT s u m a -> ParsecT s u m ()
skipMany p = void $ manyAccum (\_ _ -> []) p
manyAccum :: (a -> [a] -> [a]) -> ParsecT s u m a -> ParsecT s u m [a]
manyAccum acc p =
ParsecT $ \s cok cerr eok _ ->
let walk xs x s' _ =
unParser p s'
(seq xs $ walk $ acc x xs) -- consumed-ok
cerr -- consumed-err
manyErr -- empty-ok
(cok (acc x xs) s') -- empty-err
in unParser p s (walk []) cerr manyErr (eok [] s)
manyErr :: forall t . t
manyErr =
error
"Text.Megaparsec.Prim.many: combinator 'many' is applied to a parser \
\that accepts an empty string."
-- Parser state combinators
-- | Returns the current source position. See also 'SourcePos'.
getPosition :: Monad m => ParsecT s u m SourcePos
getPosition = statePos <$> getParserState
-- | Returns the current input.
getInput :: Monad m => ParsecT s u m s
getInput = stateInput <$> getParserState
-- | @setPosition pos@ sets the current source position to @pos@.
setPosition :: Monad m => SourcePos -> ParsecT s u m ()
setPosition pos = void $ updateParserState (\(State s _ u) -> State s pos u)
-- | @setInput input@ continues parsing with @input@. The 'getInput' and
-- @setInput@ functions can for example be used to deal with #include files.
setInput :: Monad m => s -> ParsecT s u m ()
setInput s = void $ updateParserState (\(State _ pos u) -> State s pos u)
-- | Returns the full parser state as a 'State' record.
getParserState :: Monad m => ParsecT s u m (State s u)
getParserState = updateParserState id
-- | @setParserState st@ set the full parser state to @st@.
setParserState :: Monad m => State s u -> ParsecT s u m (State s u)
setParserState st = updateParserState (const st)
-- | @updateParserState f@ applies function @f@ to the parser state.
updateParserState :: (State s u -> State s u) -> ParsecT s u m (State s u)
updateParserState f =
ParsecT $ \s _ _ eok _ -> let s' = f s in eok s' s' $ unknownError s'
-- User state combinators
-- | Returns the current user state.
getState :: Monad m => ParsecT s u m u
getState = stateUser `liftM` getParserState
-- | @putState st@ set the user state to @st@.
putState :: Monad m => u -> ParsecT s u m ()
putState u = void $ updateParserState (\s -> s { stateUser = u })
-- | @modifyState f@ applies function @f@ to the user state. Suppose
-- that we want to count identifiers in a source, we could use the user
-- state as:
--
-- > expr = Id <$> identifier <* modifyState (+1)
modifyState :: Monad m => (u -> u) -> ParsecT s u m ()
modifyState f = void $ updateParserState (\s -> s { stateUser = f (stateUser s)})