Replace BNFC-generated GFCC-parser with a faster and smaller combinator version.

1 files changed, 97 insertions, 524 deletions

diff --git a/src/GF/GFCC/Raw/ParGFCCRaw.hs b/src/GF/GFCC/Raw/ParGFCCRaw.hs
index dd3f42991..455b2713a 100644
--- a/src/GF/GFCC/Raw/ParGFCCRaw.hs
+++ b/src/GF/GFCC/Raw/ParGFCCRaw.hs
@@ -1,529 +1,102 @@
-{-# OPTIONS -fglasgow-exts -cpp #-}
-{-# OPTIONS -fno-warn-incomplete-patterns -fno-warn-overlapping-patterns #-}
 module GF.GFCC.Raw.ParGFCCRaw (parseGrammar) where
-import GF.GFCC.Raw.AbsGFCCRaw
-import GF.GFCC.Raw.LexGFCCRaw
-import GF.Data.ErrM
-#if __GLASGOW_HASKELL__ >= 503
-import Data.Array
-#else
-import Array
-#endif
-#if __GLASGOW_HASKELL__ >= 503
-import GHC.Exts
-#else
-import GlaExts
-#endif
-
--- parser produced by Happy Version 1.17
-
-newtype HappyAbsSyn  = HappyAbsSyn HappyAny
-#if __GLASGOW_HASKELL__ >= 607
-type HappyAny = GHC.Exts.Any
-#else
-type HappyAny = forall a . a
-#endif
-happyIn6 :: (Integer) -> (HappyAbsSyn )
-happyIn6 x = unsafeCoerce# x
-{-# INLINE happyIn6 #-}
-happyOut6 :: (HappyAbsSyn ) -> (Integer)
-happyOut6 x = unsafeCoerce# x
-{-# INLINE happyOut6 #-}
-happyIn7 :: (String) -> (HappyAbsSyn )
-happyIn7 x = unsafeCoerce# x
-{-# INLINE happyIn7 #-}
-happyOut7 :: (HappyAbsSyn ) -> (String)
-happyOut7 x = unsafeCoerce# x
-{-# INLINE happyOut7 #-}
-happyIn8 :: (Double) -> (HappyAbsSyn )
-happyIn8 x = unsafeCoerce# x
-{-# INLINE happyIn8 #-}
-happyOut8 :: (HappyAbsSyn ) -> (Double)
-happyOut8 x = unsafeCoerce# x
-{-# INLINE happyOut8 #-}
-happyIn9 :: (CId) -> (HappyAbsSyn )
-happyIn9 x = unsafeCoerce# x
-{-# INLINE happyIn9 #-}
-happyOut9 :: (HappyAbsSyn ) -> (CId)
-happyOut9 x = unsafeCoerce# x
-{-# INLINE happyOut9 #-}
-happyIn10 :: (Grammar) -> (HappyAbsSyn )
-happyIn10 x = unsafeCoerce# x
-{-# INLINE happyIn10 #-}
-happyOut10 :: (HappyAbsSyn ) -> (Grammar)
-happyOut10 x = unsafeCoerce# x
-{-# INLINE happyOut10 #-}
-happyIn11 :: (RExp) -> (HappyAbsSyn )
-happyIn11 x = unsafeCoerce# x
-{-# INLINE happyIn11 #-}
-happyOut11 :: (HappyAbsSyn ) -> (RExp)
-happyOut11 x = unsafeCoerce# x
-{-# INLINE happyOut11 #-}
-happyIn12 :: ([RExp]) -> (HappyAbsSyn )
-happyIn12 x = unsafeCoerce# x
-{-# INLINE happyIn12 #-}
-happyOut12 :: (HappyAbsSyn ) -> ([RExp])
-happyOut12 x = unsafeCoerce# x
-{-# INLINE happyOut12 #-}
-happyInTok :: Token -> (HappyAbsSyn )
-happyInTok x = unsafeCoerce# x
-{-# INLINE happyInTok #-}
-happyOutTok :: (HappyAbsSyn ) -> Token
-happyOutTok x = unsafeCoerce# x
-{-# INLINE happyOutTok #-}
-
-
-happyActOffsets :: HappyAddr
-happyActOffsets = HappyA# "\x00\x00\x11\x00\x00\x00\x23\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1d\x00\x1e\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1a\x00\x11\x00\x00\x00\x00\x00\x0a\x00\x00\x00\x00\x00"#
-
-happyGotoOffsets :: HappyAddr
-happyGotoOffsets = HappyA# "\xfd\xff\x1f\x00\x17\x00\x00\x00\x00\x00\x19\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x19\x00\x00\x00\x03\x00\x19\x00\x00\x00\x00\x00"#
-
-happyDefActions :: HappyAddr
-happyDefActions = HappyA# "\xf1\xff\x00\x00\xf1\xff\x00\x00\xfc\xff\x00\x00\xf5\xff\xf4\xff\xf3\xff\xf6\xff\x00\x00\x00\x00\xf2\xff\xfb\xff\xfa\xff\xf9\xff\x00\x00\xf8\xff\xf0\xff\xf1\xff\x00\x00\xf7\xff"#
-
-happyCheck :: HappyAddr
-happyCheck = HappyA# "\xff\xff\x04\x00\x01\x00\x06\x00\x03\x00\x04\x00\x05\x00\x06\x00\x07\x00\x06\x00\x09\x00\x01\x00\x02\x00\x03\x00\x04\x00\x05\x00\x06\x00\x07\x00\x01\x00\x03\x00\x03\x00\x04\x00\x05\x00\x06\x00\x07\x00\x00\x00\x01\x00\x02\x00\x03\x00\x06\x00\x05\x00\x00\x00\x01\x00\x02\x00\x03\x00\x09\x00\x05\x00\x07\x00\x09\x00\x04\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"#
-
-happyTable :: HappyAddr
-happyTable = HappyA# "\x00\x00\x10\x00\x0c\x00\x11\x00\x0d\x00\x05\x00\x0e\x00\x0f\x00\x10\x00\x14\x00\xff\xff\x0c\x00\x16\x00\x0d\x00\x05\x00\x0e\x00\x0f\x00\x10\x00\x0c\x00\x13\x00\x0d\x00\x05\x00\x0e\x00\x0f\x00\x10\x00\x06\x00\x07\x00\x08\x00\x09\x00\x05\x00\x12\x00\x06\x00\x07\x00\x08\x00\x09\x00\xff\xff\x0a\x00\x10\x00\xff\xff\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"#
-
-happyReduceArr = array (3, 15) [
-	(3 , happyReduce_3),
-	(4 , happyReduce_4),
-	(5 , happyReduce_5),
-	(6 , happyReduce_6),
-	(7 , happyReduce_7),
-	(8 , happyReduce_8),
-	(9 , happyReduce_9),
-	(10 , happyReduce_10),
-	(11 , happyReduce_11),
-	(12 , happyReduce_12),
-	(13 , happyReduce_13),
-	(14 , happyReduce_14),
-	(15 , happyReduce_15)
-	]
-
-happy_n_terms = 10 :: Int
-happy_n_nonterms = 7 :: Int
-
-happyReduce_3 = happySpecReduce_1  0# happyReduction_3
-happyReduction_3 happy_x_1
-	 =  case happyOutTok happy_x_1 of { (PT _ (TI happy_var_1)) -> 
-	happyIn6
-		 ((read happy_var_1) :: Integer
-	)}
-
-happyReduce_4 = happySpecReduce_1  1# happyReduction_4
-happyReduction_4 happy_x_1
-	 =  case happyOutTok happy_x_1 of { (PT _ (TL happy_var_1)) -> 
-	happyIn7
-		 (happy_var_1
-	)}
-
-happyReduce_5 = happySpecReduce_1  2# happyReduction_5
-happyReduction_5 happy_x_1
-	 =  case happyOutTok happy_x_1 of { (PT _ (TD happy_var_1)) -> 
-	happyIn8
-		 ((read happy_var_1) :: Double
-	)}
-
-happyReduce_6 = happySpecReduce_1  3# happyReduction_6
-happyReduction_6 happy_x_1
-	 =  case happyOutTok happy_x_1 of { (PT _ (T_CId happy_var_1)) -> 
-	happyIn9
-		 (CId (happy_var_1)
-	)}
-
-happyReduce_7 = happySpecReduce_1  4# happyReduction_7
-happyReduction_7 happy_x_1
-	 =  case happyOut12 happy_x_1 of { happy_var_1 -> 
-	happyIn10
-		 (Grm (reverse happy_var_1)
-	)}
-
-happyReduce_8 = happyReduce 4# 5# happyReduction_8
-happyReduction_8 (happy_x_4 `HappyStk`
-	happy_x_3 `HappyStk`
-	happy_x_2 `HappyStk`
-	happy_x_1 `HappyStk`
-	happyRest)
-	 = case happyOut9 happy_x_2 of { happy_var_2 -> 
-	case happyOut12 happy_x_3 of { happy_var_3 -> 
-	happyIn11
-		 (App happy_var_2 (reverse happy_var_3)
-	) `HappyStk` happyRest}}
-
-happyReduce_9 = happySpecReduce_1  5# happyReduction_9
-happyReduction_9 happy_x_1
-	 =  case happyOut9 happy_x_1 of { happy_var_1 -> 
-	happyIn11
-		 (AId happy_var_1
-	)}
-
-happyReduce_10 = happySpecReduce_1  5# happyReduction_10
-happyReduction_10 happy_x_1
-	 =  case happyOut6 happy_x_1 of { happy_var_1 -> 
-	happyIn11
-		 (AInt happy_var_1
-	)}
-
-happyReduce_11 = happySpecReduce_1  5# happyReduction_11
-happyReduction_11 happy_x_1
-	 =  case happyOut7 happy_x_1 of { happy_var_1 -> 
-	happyIn11
-		 (AStr happy_var_1
-	)}
-
-happyReduce_12 = happySpecReduce_1  5# happyReduction_12
-happyReduction_12 happy_x_1
-	 =  case happyOut8 happy_x_1 of { happy_var_1 -> 
-	happyIn11
-		 (AFlt happy_var_1
-	)}
-
-happyReduce_13 = happySpecReduce_1  5# happyReduction_13
-happyReduction_13 happy_x_1
-	 =  happyIn11
-		 (AMet
-	)
-
-happyReduce_14 = happySpecReduce_0  6# happyReduction_14
-happyReduction_14  =  happyIn12
-		 ([]
-	)
-
-happyReduce_15 = happySpecReduce_2  6# happyReduction_15
-happyReduction_15 happy_x_2
-	happy_x_1
-	 =  case happyOut12 happy_x_1 of { happy_var_1 -> 
-	case happyOut11 happy_x_2 of { happy_var_2 -> 
-	happyIn12
-		 (flip (:) happy_var_1 happy_var_2
-	)}}
-
-happyNewToken action sts stk [] =
-	happyDoAction 9# notHappyAtAll action sts stk []
-
-happyNewToken action sts stk (tk:tks) =
-	let cont i = happyDoAction i tk action sts stk tks in
-	case tk of {
-	PT _ (TS "(") -> cont 1#;
-	PT _ (TS ")") -> cont 2#;
-	PT _ (TS "?") -> cont 3#;
-	PT _ (TI happy_dollar_dollar) -> cont 4#;
-	PT _ (TL happy_dollar_dollar) -> cont 5#;
-	PT _ (TD happy_dollar_dollar) -> cont 6#;
-	PT _ (T_CId happy_dollar_dollar) -> cont 7#;
-	_ -> cont 8#;
-	_ -> happyError' (tk:tks)
-	}
-
-happyError_ tk tks = happyError' (tk:tks)
-
-happyThen :: () => Err a -> (a -> Err b) -> Err b
-happyThen = (thenM)
-happyReturn :: () => a -> Err a
-happyReturn = (returnM)
-happyThen1 m k tks = (thenM) m (\a -> k a tks)
-happyReturn1 :: () => a -> b -> Err a
-happyReturn1 = \a tks -> (returnM) a
-happyError' :: () => [Token] -> Err a
-happyError' = happyError
-
-pGrammar tks = happySomeParser where
-  happySomeParser = happyThen (happyParse 0# tks) (\x -> happyReturn (happyOut10 x))
 
-pRExp tks = happySomeParser where
-  happySomeParser = happyThen (happyParse 1# tks) (\x -> happyReturn (happyOut11 x))
-
-pListRExp tks = happySomeParser where
-  happySomeParser = happyThen (happyParse 2# tks) (\x -> happyReturn (happyOut12 x))
-
-happySeq = happyDontSeq
+import GF.GFCC.Raw.AbsGFCCRaw
 
+import Control.Monad
+import Data.Char
 
 parseGrammar :: String -> IO Grammar
-parseGrammar f = case pGrammar (myLexer f) of
-  Ok g -> return g
-  Bad s -> error s
-
-returnM :: a -> Err a
-returnM = return
-
-thenM :: Err a -> (a -> Err b) -> Err b
-thenM = (>>=)
-
-happyError :: [Token] -> Err a
-happyError ts =
-  Bad $ "syntax error at " ++ tokenPos ts ++ 
-  case ts of
-    [] -> []
-    [Err _] -> " due to lexer error"
-    _ -> " before " ++ unwords (map prToken (take 4 ts))
-
-myLexer = tokens
-{-# LINE 1 "templates/GenericTemplate.hs" #-}
-{-# LINE 1 "templates/GenericTemplate.hs" #-}
-{-# LINE 1 "<built-in>" #-}
-{-# LINE 1 "<command line>" #-}
-{-# LINE 1 "templates/GenericTemplate.hs" #-}
--- Id: GenericTemplate.hs,v 1.26 2005/01/14 14:47:22 simonmar Exp 
-
-{-# LINE 28 "templates/GenericTemplate.hs" #-}
-
-
-data Happy_IntList = HappyCons Int# Happy_IntList
-
-
-
-
-
-{-# LINE 49 "templates/GenericTemplate.hs" #-}
-
-{-# LINE 59 "templates/GenericTemplate.hs" #-}
-
-{-# LINE 68 "templates/GenericTemplate.hs" #-}
-
-infixr 9 `HappyStk`
-data HappyStk a = HappyStk a (HappyStk a)
-
------------------------------------------------------------------------------
--- starting the parse
-
-happyParse start_state = happyNewToken start_state notHappyAtAll notHappyAtAll
-
------------------------------------------------------------------------------
--- Accepting the parse
-
--- If the current token is 0#, it means we've just accepted a partial
--- parse (a %partial parser).  We must ignore the saved token on the top of
--- the stack in this case.
-happyAccept 0# tk st sts (_ `HappyStk` ans `HappyStk` _) =
-	happyReturn1 ans
-happyAccept j tk st sts (HappyStk ans _) = 
-	(happyTcHack j (happyTcHack st)) (happyReturn1 ans)
-
------------------------------------------------------------------------------
--- Arrays only: do the next action
-
-
-
-happyDoAction i tk st
-	= {- nothing -}
-
-
-	  case action of
-		0#		  -> {- nothing -}
-				     happyFail i tk st
-		-1# 	  -> {- nothing -}
-				     happyAccept i tk st
-		n | (n <# (0# :: Int#)) -> {- nothing -}
-
-				     (happyReduceArr ! rule) i tk st
-				     where rule = (I# ((negateInt# ((n +# (1# :: Int#))))))
-		n		  -> {- nothing -}
-
-
-				     happyShift new_state i tk st
-				     where new_state = (n -# (1# :: Int#))
-   where off    = indexShortOffAddr happyActOffsets st
-	 off_i  = (off +# i)
-	 check  = if (off_i >=# (0# :: Int#))
-			then (indexShortOffAddr happyCheck off_i ==#  i)
-			else False
- 	 action | check     = indexShortOffAddr happyTable off_i
-		| otherwise = indexShortOffAddr happyDefActions st
-
-{-# LINE 127 "templates/GenericTemplate.hs" #-}
-
-
-indexShortOffAddr (HappyA# arr) off =
-#if __GLASGOW_HASKELL__ > 500
-	narrow16Int# i
-#elif __GLASGOW_HASKELL__ == 500
-	intToInt16# i
-#else
-	(i `iShiftL#` 16#) `iShiftRA#` 16#
-#endif
-  where
-#if __GLASGOW_HASKELL__ >= 503
-	i = word2Int# ((high `uncheckedShiftL#` 8#) `or#` low)
-#else
-	i = word2Int# ((high `shiftL#` 8#) `or#` low)
-#endif
-	high = int2Word# (ord# (indexCharOffAddr# arr (off' +# 1#)))
-	low  = int2Word# (ord# (indexCharOffAddr# arr off'))
-	off' = off *# 2#
-
-
-
-
-
-data HappyAddr = HappyA# Addr#
-
-
-
-
------------------------------------------------------------------------------
--- HappyState data type (not arrays)
-
-{-# LINE 170 "templates/GenericTemplate.hs" #-}
-
------------------------------------------------------------------------------
--- Shifting a token
-
-happyShift new_state 0# tk st sts stk@(x `HappyStk` _) =
-     let i = (case unsafeCoerce# x of { (I# (i)) -> i }) in
---     trace "shifting the error token" $
-     happyDoAction i tk new_state (HappyCons (st) (sts)) (stk)
-
-happyShift new_state i tk st sts stk =
-     happyNewToken new_state (HappyCons (st) (sts)) ((happyInTok (tk))`HappyStk`stk)
-
--- happyReduce is specialised for the common cases.
-
-happySpecReduce_0 i fn 0# tk st sts stk
-     = happyFail 0# tk st sts stk
-happySpecReduce_0 nt fn j tk st@((action)) sts stk
-     = happyGoto nt j tk st (HappyCons (st) (sts)) (fn `HappyStk` stk)
-
-happySpecReduce_1 i fn 0# tk st sts stk
-     = happyFail 0# tk st sts stk
-happySpecReduce_1 nt fn j tk _ sts@((HappyCons (st@(action)) (_))) (v1`HappyStk`stk')
-     = let r = fn v1 in
-       happySeq r (happyGoto nt j tk st sts (r `HappyStk` stk'))
-
-happySpecReduce_2 i fn 0# tk st sts stk
-     = happyFail 0# tk st sts stk
-happySpecReduce_2 nt fn j tk _ (HappyCons (_) (sts@((HappyCons (st@(action)) (_))))) (v1`HappyStk`v2`HappyStk`stk')
-     = let r = fn v1 v2 in
-       happySeq r (happyGoto nt j tk st sts (r `HappyStk` stk'))
-
-happySpecReduce_3 i fn 0# tk st sts stk
-     = happyFail 0# tk st sts stk
-happySpecReduce_3 nt fn j tk _ (HappyCons (_) ((HappyCons (_) (sts@((HappyCons (st@(action)) (_))))))) (v1`HappyStk`v2`HappyStk`v3`HappyStk`stk')
-     = let r = fn v1 v2 v3 in
-       happySeq r (happyGoto nt j tk st sts (r `HappyStk` stk'))
-
-happyReduce k i fn 0# tk st sts stk
-     = happyFail 0# tk st sts stk
-happyReduce k nt fn j tk st sts stk
-     = case happyDrop (k -# (1# :: Int#)) sts of
-	 sts1@((HappyCons (st1@(action)) (_))) ->
-        	let r = fn stk in  -- it doesn't hurt to always seq here...
-       		happyDoSeq r (happyGoto nt j tk st1 sts1 r)
-
-happyMonadReduce k nt fn 0# tk st sts stk
-     = happyFail 0# tk st sts stk
-happyMonadReduce k nt fn j tk st sts stk =
-        happyThen1 (fn stk tk) (\r -> happyGoto nt j tk st1 sts1 (r `HappyStk` drop_stk))
-       where sts1@((HappyCons (st1@(action)) (_))) = happyDrop k (HappyCons (st) (sts))
-             drop_stk = happyDropStk k stk
-
-happyMonad2Reduce k nt fn 0# tk st sts stk
-     = happyFail 0# tk st sts stk
-happyMonad2Reduce k nt fn j tk st sts stk =
-       happyThen1 (fn stk tk) (\r -> happyNewToken new_state sts1 (r `HappyStk` drop_stk))
-       where sts1@((HappyCons (st1@(action)) (_))) = happyDrop k (HappyCons (st) (sts))
-             drop_stk = happyDropStk k stk
-
-             off    = indexShortOffAddr happyGotoOffsets st1
-             off_i  = (off +# nt)
-             new_state = indexShortOffAddr happyTable off_i
-
-
-
-
-happyDrop 0# l = l
-happyDrop n (HappyCons (_) (t)) = happyDrop (n -# (1# :: Int#)) t
-
-happyDropStk 0# l = l
-happyDropStk n (x `HappyStk` xs) = happyDropStk (n -# (1#::Int#)) xs
-
------------------------------------------------------------------------------
--- Moving to a new state after a reduction
-
-
-happyGoto nt j tk st = 
-   {- nothing -}
-   happyDoAction j tk new_state
-   where off    = indexShortOffAddr happyGotoOffsets st
-	 off_i  = (off +# nt)
- 	 new_state = indexShortOffAddr happyTable off_i
-
-
-
-
------------------------------------------------------------------------------
--- Error recovery (0# is the error token)
-
--- parse error if we are in recovery and we fail again
-happyFail  0# tk old_st _ stk =
---	trace "failing" $ 
-    	happyError_ tk
-
-{-  We don't need state discarding for our restricted implementation of
-    "error".  In fact, it can cause some bogus parses, so I've disabled it
-    for now --SDM
-
--- discard a state
-happyFail  0# tk old_st (HappyCons ((action)) (sts)) 
-						(saved_tok `HappyStk` _ `HappyStk` stk) =
---	trace ("discarding state, depth " ++ show (length stk))  $
-	happyDoAction 0# tk action sts ((saved_tok`HappyStk`stk))
--}
-
--- Enter error recovery: generate an error token,
---                       save the old token and carry on.
-happyFail  i tk (action) sts stk =
---      trace "entering error recovery" $
-	happyDoAction 0# tk action sts ( (unsafeCoerce# (I# (i))) `HappyStk` stk)
-
--- Internal happy errors:
-
-notHappyAtAll = error "Internal Happy error\n"
-
------------------------------------------------------------------------------
--- Hack to get the typechecker to accept our action functions
-
-
-happyTcHack :: Int# -> a -> a
-happyTcHack x y = y
-{-# INLINE happyTcHack #-}
-
-
------------------------------------------------------------------------------
--- Seq-ing.  If the --strict flag is given, then Happy emits 
---	happySeq = happyDoSeq
--- otherwise it emits
--- 	happySeq = happyDontSeq
-
-happyDoSeq, happyDontSeq :: a -> b -> b
-happyDoSeq   a b = a `seq` b
-happyDontSeq a b = b
-
------------------------------------------------------------------------------
--- Don't inline any functions from the template.  GHC has a nasty habit
--- of deciding to inline happyGoto everywhere, which increases the size of
--- the generated parser quite a bit.
-
-
-{-# NOINLINE happyDoAction #-}
-{-# NOINLINE happyTable #-}
-{-# NOINLINE happyCheck #-}
-{-# NOINLINE happyActOffsets #-}
-{-# NOINLINE happyGotoOffsets #-}
-{-# NOINLINE happyDefActions #-}
-
-{-# NOINLINE happyShift #-}
-{-# NOINLINE happySpecReduce_0 #-}
-{-# NOINLINE happySpecReduce_1 #-}
-{-# NOINLINE happySpecReduce_2 #-}
-{-# NOINLINE happySpecReduce_3 #-}
-{-# NOINLINE happyReduce #-}
-{-# NOINLINE happyMonadReduce #-}
-{-# NOINLINE happyGoto #-}
-{-# NOINLINE happyFail #-}
-
--- end of Happy Template.
+parseGrammar s = case runP pGrammar s of
+                   Just (x,"") -> return x
+                   _           -> fail "Parse error"
+
+pGrammar :: P Grammar
+pGrammar = liftM Grm pTerms
+
+pTerms :: P [RExp]
+pTerms = liftM2 (:) pTerm pTerms <++ (skipSpaces >> return [])
+
+pTerm :: P RExp
+pTerm = skipSpaces >> (pApp <++ pId <++ pNum <++ pStr <++ pMeta)
+  where pApp = between (char '(') (char ')') 
+               (liftM2 App pIdent pTerms)
+        pId = liftM AId pIdent
+        pStr = char '"' >> liftM AStr (manyTill (pEsc <++ get) (char '"'))
+        -- FIXME: what escapes are used?
+        pEsc = char '\\' >> get
+        -- FIXME: what formats?
+        pNum = do x <- munch1 isDigit
+                  ((char '.' >> munch1 isDigit >>= \y -> return (AFlt (read (x++"."++y))))
+                   <++
+                   return (AInt (read x)))
+        pMeta = char '?' >> return AMet
+        pIdent = liftM CId $ liftM2 (:) (satisfy isIdentFirst) (munch isIdentRest)
+        isIdentFirst c = c == '_' || isLetter c
+        isIdentRest c = c == '_' || c == '\'' || isAlphaNum c
+
+-- Parser combinators with only left-biased choice
+
+newtype P a = P { runP :: String -> Maybe (a,String) }
+
+instance Monad P where
+    return x = P (\ts -> Just (x,ts))
+    P p >>= f = P (\ts -> p ts >>= \ (x,ts') -> runP (f x) ts')
+    fail _ = pfail
+
+instance MonadPlus P where
+    mzero = pfail
+    mplus = (<++)
+
+
+get :: P Char
+get = P (\ts -> case ts of
+                  [] -> Nothing
+                  c:cs -> Just (c,cs))
+
+look :: P String
+look = P (\ts -> Just (ts,ts))
+
+(<++) :: P a -> P a -> P a
+P p <++ P q = P (\ts -> p ts `mplus` q ts)
+
+pfail :: P a
+pfail = P (\ts -> Nothing)
+
+satisfy :: (Char -> Bool) -> P Char
+satisfy p = do c <- get
+               if p c then return c else pfail
+
+char :: Char -> P Char
+char c = satisfy (c==)
+
+string :: String -> P String
+string this = look >>= scan this
+    where
+      scan []     _               = return this
+      scan (x:xs) (y:ys) | x == y = get >> scan xs ys
+      scan _      _               = pfail
+
+skipSpaces :: P ()
+skipSpaces = look >>= skip
+    where
+      skip (c:s) | isSpace c = get >> skip s
+      skip _                 = return ()
+
+manyTill :: P a -> P end -> P [a]
+manyTill p end = scan
+  where scan = (end >> return []) <++ liftM2 (:) p scan
+
+munch :: (Char -> Bool) -> P String
+munch p = munch1 p <++ return []
+
+munch1 :: (Char -> Bool) -> P String
+munch1 p = liftM2 (:) (satisfy p) (munch p)
+
+choice :: [P a] -> P a
+choice = msum
+
+between :: P open -> P close -> P a -> P a
+between open close p = do open
+                          x <- p
+                          close
+                          return x