c083497...master · syntax

git.iko.soy/syntax

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Data/Syntax.hs+89−12

since splitsnapshots

unifiedsplit

@@ -10,23 +10,28 @@ License : MIT

10Maintainer : Paweł Nowak <pawel834@gmail.com>

11Stability : experimental

13−Abstract syntax descriptions based on semi-isomorphisms.

13+Reversible parsing and pretty-printing.

14-}

15module Data.Syntax (

16 -- * Syntax.

17 Syntax(..),

18+ Isolable(..),

18 -- * Common isomorphisms.

19 -- * Common isomorphisms.

19 packed

20 packed

20 ) where

21 ) where

22−import Prelude hiding (take, takeWhile)

23+import Prelude hiding (take, takeWhile, id, (.))

25+import Control.Category

24−import Control.Category.Reader

26+import Control.Category.Reader

27+import Control.Category.Structures

25−import Control.Lens.Iso

28+import Control.Lens.Iso

26−import Control.Lens.SemiIso

29+import Control.Lens.SemiIso

27−import Control.SIArrow

30+import Control.SIArrow

28−import Data.MonoTraversable

31+import Data.MonoTraversable

29−import Data.Sequences hiding (take, takeWhile)

32+import Data.Sequences hiding (take, takeWhile, replicate)

33+import qualified Data.Vector as V

34+import qualified Data.Vector.Unboxed as VU

31-- | An isomorphism between a sequence and a list of its elements.

36-- | An isomorphism between a sequence and a list of its elements.

32packed :: IsSequence seq => Iso' seq [Element seq]

37packed :: IsSequence seq => Iso' seq [Element seq]

@@ -34,11 +39,11 @@ packed = iso otoList fromList

35-- | An abstract syntax description based on semi-isomorphisms.

40-- | An abstract syntax description based on semi-isomorphisms.

36--

41--

37−-- This class can be implemented by both parsers and printers (and maybe more?).

42+-- This class can be implemented by both parsers and printers.

38−--

43+--

39-- The usual use is to write a polymorphic syntax description and instantiate it

44-- The usual use is to write a polymorphic syntax description and instantiate it

40−-- both as a parser and a printer. An example is available in the 'syntax-example'

45+-- both as a parser and a printer. Examples are available in 'syntax-example' and

41−-- package.

46+-- 'syntax-example-json' packages.

42--

47--

43-- Methods of this class try to mimic "Data.Attoparsec.Text" interface.

48-- Methods of this class try to mimic "Data.Attoparsec.Text" interface.

44class ( SIArrow syn

49class ( SIArrow syn

@@ -94,6 +99,58 @@ class ( SIArrow syn

94 takeTill1 :: (Element (Seq syn) -> Bool) -> syn () (Seq syn)

99 takeTill1 :: (Element (Seq syn) -> Bool) -> syn () (Seq syn)

95 takeTill1 p = takeWhile1 (not . p)

100 takeTill1 p = takeWhile1 (not . p)

101

102+ -- | Constant size vector. The default implementation uses lists, but

103+ -- "syntax-attoparsec" and "syntax-printer" override it with an efficient

104+ -- implementation that works on a vector directly.

105+ --

106+ -- @vecN n e@ describes a size @n@ vector with elements @e@.

107+ --

108+ -- Also see 'Data.Syntax.Combinator.vec'.

109+ vecN :: Int -> syn () a -> syn () (V.Vector a)

110+ vecN n e = packed /$/ sireplicate n e

111+

112+ -- | Constant size vector with index-aware element. The default implementation

113+ -- uses lists, but "syntax-attoparsec" and "syntax-printer" override it with an

114+ -- efficient implementation that works on a vector directly.

115+ --

116+ -- @ivecN n e@ describes a size @n@ vector with elements @e@. Each element

117+ -- gets its index and should output a value and the index unchanged.

118+ --

119+ -- Also see 'Data.Syntax.Combinator.ivec'.

120+ ivecN :: Int -> syn Int (Int, a) -> syn () (V.Vector a)

121+ ivecN n e = (packed /$/)

122+ $ sisequence

123+ $ map (\(i, e') -> constant i ^>> e'

124+ >>> first (sipure (constant i))

125+ >># unit . swapped)

126+ $ zip [0 .. n-1] (replicate n e)

127+

128+ -- | Constant size unboxed vector. The default implementation uses lists, but

129+ -- "syntax-attoparsec" and "syntax-printer" override it with an efficient

130+ -- implementation that works on a vector directly.

131+ --

132+ -- @vecN n e@ describes a size @n@ vector with elements @e@.

133+ --

134+ -- Also see 'Data.Syntax.Combinator.vec'.

135+ uvecN :: VU.Unbox a => Int -> syn () a -> syn () (VU.Vector a)

136+ uvecN n e = packed /$/ sireplicate n e

137+

138+ -- | Constant size unboxed vector with index-aware element. The default implementation

139+ -- uses lists, but "syntax-attoparsec" and "syntax-printer" override it with an

140+ -- efficient implementation that works on a vector directly.

141+ --

142+ -- @ivecN n e@ describes a size @n@ vector with elements @e@. Each element

143+ -- gets its index and should output a value and the index unchanged.

144+ --

145+ -- Also see 'Data.Syntax.Combinator.ivec'.

146+ uivecN :: VU.Unbox a => Int -> syn Int (Int, a) -> syn () (VU.Vector a)

147+ uivecN n e = (packed /$/)

148+ $ sisequence

149+ $ map (\(i, e') -> constant i ^>> e'

150+ >>> first (sipure (constant i))

151+ >># unit . swapped)

152+ $ zip [0 .. n-1] (replicate n e)

153+

97 {-# MINIMAL anyChar #-}

154 {-# MINIMAL anyChar #-}

155

99instance Syntax syn => Syntax (ReaderCT env syn) where

156instance Syntax syn => Syntax (ReaderCT env syn) where

@@ -109,3 +166,23 @@ instance Syntax syn => Syntax (ReaderCT env syn) where

109 takeWhile1 = clift . takeWhile1

166 takeWhile1 = clift . takeWhile1

110 takeTill = clift . takeTill

167 takeTill = clift . takeTill

111 takeTill1 = clift . takeTill1

168 takeTill1 = clift . takeTill1

169+ vecN n e = ReaderCT $ vecN n . runReaderCT e

170+ ivecN n e = ReaderCT $ ivecN n . runReaderCT e

171+ uvecN n e = ReaderCT $ uvecN n . runReaderCT e

172+ uivecN n e = ReaderCT $ uivecN n . runReaderCT e

173+

174+-- | Execute a computation in an isolated context.

175+--

176+-- The motivating example: you want to write a function

177+--

178+-- > serializeList :: Syntax syn => syn () a -> syn () [a]

179+--

180+-- Notice that we cannot just use simany, because the first @syn () a@

181+-- could eat the entire sequence (even though we printed more than 1 value!), so

182+-- we have to insert some kind of separators between the element. But how can we

183+-- be sure that @syn () a@ will not eat our separators? We can't! Thats why we

184+-- have to do the parsing in two stages: first extract the sequence between separators,

185+-- then run the @syn () a@ on this sequence.

186+class Syntax syn => Isolable syn where

187+ -- | Turns a computation into one executed in an isolated context.

188+ isolate :: syn () b -> syn (Seq syn) b

Data/Syntax/Char.hs+1

@@ -26,6 +26,7 @@ module Data.Syntax.Char (

26 ) where

28import Control.Category.Reader

29+import Control.Category.Structures

29import Control.Lens.SemiIso

30import Control.Lens.SemiIso

30import Control.SIArrow

31import Control.SIArrow

31import Data.Bits

32import Data.Bits

Data/Syntax/Combinator.hs+149−11

@@ -1,3 +1,6 @@

1+{-# LANGUAGE RankNTypes #-}

2+{-# LANGUAGE ScopedTypeVariables #-}

3+{-# LANGUAGE FlexibleContexts #-}

1{- |

4{- |

2Module : Data.Syntax.Combinator

5Module : Data.Syntax.Combinator

3Description : Combinators that work with any sequence type.

6Description : Combinators that work with any sequence type.

@@ -9,11 +12,50 @@ Stability : experimental

10Combinators that work with any sequence type.

13Combinators that work with any sequence type.

11-}

14-}

12−module Data.Syntax.Combinator where

15+module Data.Syntax.Combinator

16+ (

17+ -- * Combinators.

18+ optional,

19+ opt,

20+ opt_,

21+ choice,

22+ eitherOf,

14−import Control.Lens

24+ -- * Lists.

25+ manyTill,

26+ sepBy,

27+ sepBy1,

28+

29+ -- * Arrowized combinators.

30+ takeArr,

31+

32+ -- * Vectors.

33+ vecNSepBy,

34+ ivecNSepBy,

35+ vec,

36+ vecSepBy,

37+ ivec,

38+ ivecSepBy,

39+

40+ -- * Unboxed vectors.

41+ uvecNSepBy,

42+ uivecNSepBy,

43+ uvec,

44+ uvecSepBy,

45+ uivec,

46+ uivecSepBy

47+ ) where

48+

49+import Control.Category

50+import Control.Category.Structures

51+import Control.Lens

15−import Control.Lens.SemiIso

52+import Control.Lens.SemiIso

16−import Control.SIArrow

53+import Control.SIArrow

54+import qualified Data.MonoTraversable as Seq

55+import Data.Syntax

56+import qualified Data.Vector as V

57+import qualified Data.Vector.Unboxed as VU

58+import Prelude hiding (id, (.), take)

18-- | One or zero occurences of @f@.

60-- | One or zero occurences of @f@.

19optional :: SIArrow cat => cat () a -> cat () (Maybe a)

61optional :: SIArrow cat => cat () a -> cat () (Maybe a)

@@ -28,6 +70,15 @@ opt_ :: SIArrow cat => cat () () -> cat () ()

28opt_ f = semiIso (const (Left "opt_")) Right /$/ f

70opt_ f = semiIso (const (Left "opt_")) Right /$/ f

29 /+/ sipure id

71 /+/ sipure id

73+-- | Tries to apply the actions in the list in order, until one of

74+-- them succeeds. Returns the value of the succeeding action.

75+choice :: SIArrow cat => [cat () a] -> cat () a

76+choice = foldr (/+/) (sifail "choice: all alternatives failed")

77+

78+-- | Combine two alternatives.

79+eitherOf :: SIArrow cat => cat () a -> cat () b -> cat () (Either a b)

80+eitherOf a b = _Left /$/ a /+/ _Right /$/ b

81+

31-- | @manyTill p end@ applies action p zero or more times until action

82-- | @manyTill p end@ applies action p zero or more times until action

32-- end succeeds, and returns the list of values returned by p.

83-- end succeeds, and returns the list of values returned by p.

33manyTill :: SIArrow cat => cat () a -> cat () () -> cat () [a]

84manyTill :: SIArrow cat => cat () a -> cat () () -> cat () [a]

@@ -42,11 +93,98 @@ sepBy v s = sepBy1 v s /+/ sipure _Empty

42sepBy1 :: SIArrow cat => cat () a -> cat () () -> cat () [a]

93sepBy1 :: SIArrow cat => cat () a -> cat () () -> cat () [a]

43sepBy1 v s = _Cons /$/ v /*/ (s */ sepBy1 v s /+/ sipure _Empty)

94sepBy1 v s = _Cons /$/ v /*/ (s */ sepBy1 v s /+/ sipure _Empty)

45−-- | Tries to apply the actions in the list in order, until one of

96+-- | A string of given length.

46−-- them succeeds. Returns the value of the succeeding action.

97+takeArr :: Syntax syn => syn Int (Seq syn)

47−choice :: SIArrow cat => [cat () a] -> cat () a

98+takeArr = sibind $ iso (\n -> constant n #>> take n)

48−choice = foldr (/+/) (sifail "choice: all alternatives failed")

99+ (\s -> constant (Seq.olength s) #>> take (Seq.olength s))

100

50−-- | Combine two alternatives.

101+-- | Constant size vector with separators.

51−eitherOf :: SIArrow cat => cat () a -> cat () b -> cat () (Either a b)

102+--

52−eitherOf a b = _Left /$/ a /+/ _Right /$/ b

103+-- @vecNSepBy n e sep@ describes a size @n@ vector with elements @e@ separated by @sep@.

104+vecNSepBy :: Syntax syn => Int -> syn () a -> syn () () -> syn () (V.Vector a)

105+vecNSepBy n e sep = ivecNSepBy n (unit ^>> second e) sep

106+

107+-- | Constant size vector with separators and index-aware elements.

108+--

109+-- @ivecNSepBy n e sep@ describes a size @n@ vector with elements @e@ separated by @sep@.

110+-- Each element gets its index and should output a value and the index unchanged.

111+ivecNSepBy :: Syntax syn => Int -> syn Int (Int, a) -> syn () () -> syn () (V.Vector a)

112+ivecNSepBy n e sep = ivecN n $ sibind $ iso el (el . fst)

113+ where

114+ el k | k < n - 1 = unit ^>> e *** sep >># unit

115+ | otherwise = e

116+

117+-- | Runtime sized vector. The size can depend on the result of some computation.

118+--

119+-- @vec e@ describes a vector with elements @e@.

120+vec :: Syntax syn => syn () a -> syn Int (V.Vector a)

121+vec e = vecSepBy e (siarr id)

122+

123+-- | Runtime sized vector with separators. The size can depend on the result of some

124+-- computation.

125+--

126+-- @vecSepBy e sep@ describes a vector with elements @e@ separated by @sep@.

127+vecSepBy :: Syntax syn => syn () a -> syn () () -> syn Int (V.Vector a)

128+vecSepBy e sep = ivecSepBy (unit ^>> second e) sep

129+

130+-- | Runtime sized vector with index-aware elements. The size can depend on the result

131+-- of some computation.

132+--

133+-- @ivec e@ describes a vector with elements @e@.

134+ivec :: Syntax syn => syn Int (Int, a) -> syn Int (V.Vector a)

135+ivec e = ivecSepBy e (siarr id)

136+

137+-- | Runtime sized vector with index-aware elements and separators. The size can depend

138+-- on the result of some computation.

139+--

140+-- @ivecSepBy e sep@ describes a vector with elements @e@ separated by @sep@.

141+ivecSepBy :: Syntax syn => syn Int (Int, a) -> syn () () -> syn Int (V.Vector a)

142+ivecSepBy e sep = sibind $ iso (\n -> constant n #>> ivecNSepBy n e sep)

143+ (\v -> constant (V.length v) #>> ivecNSepBy (V.length v) e sep)

144+

145+-- | Constant size unboxed vector with separators.

146+--

147+-- @uvecNSepBy n e sep@ describes a size @n@ vector with elements @e@ separated by @sep@.

148+uvecNSepBy :: (Syntax syn, VU.Unbox a) => Int -> syn () a -> syn () () -> syn () (VU.Vector a)

149+uvecNSepBy n e sep = uivecNSepBy n (unit ^>> second e) sep

150+

151+-- | Constant size unboxed vector with separators and index-aware elements.

152+--

153+-- @uivecNSepBy n e sep@ describes a size @n@ vector with elements @e@ separated by @sep@.

154+-- Each element gets its index and should output a value and the index unchanged.

155+uivecNSepBy :: (Syntax syn, VU.Unbox a) => Int -> syn Int (Int, a)

156+ -> syn () () -> syn () (VU.Vector a)

157+uivecNSepBy n e sep = uivecN n $ sibind $ iso el (el . fst)

158+ where

159+ el k | k < n - 1 = unit ^>> e *** sep >># unit

160+ | otherwise = e

161+

162+-- | Runtime sized unboxed vector. The size can depend on the result of some computation.

163+--

164+-- @uvec e@ describes a vector with elements @e@.

165+uvec :: (Syntax syn, VU.Unbox a) => syn () a -> syn Int (VU.Vector a)

166+uvec e = uvecSepBy e (siarr id)

167+

168+-- | Runtime sized unboxed vector with separators. The size can depend on the result of some

169+-- computation.

170+--

171+-- @uvecSepBy e sep@ describes a vector with elements @e@ separated by @sep@.

172+uvecSepBy :: (Syntax syn, VU.Unbox a) => syn () a -> syn () () -> syn Int (VU.Vector a)

173+uvecSepBy e sep = uivecSepBy (unit ^>> second e) sep

174+

175+-- | Runtime sized unboxed vector with index-aware elements. The size can depend on the result

176+-- of some computation.

177+--

178+-- @uivec e@ describes a vector with elements @e@.

179+uivec :: (Syntax syn, VU.Unbox a) => syn Int (Int, a) -> syn Int (VU.Vector a)

180+uivec e = uivecSepBy e (siarr id)

181+

182+-- | Runtime sized unboxed vector with index-aware elements and separators. The size can depend

183+-- on the result of some computation.

184+--

185+-- @uivecSepBy e sep@ describes a vector with elements @e@ separated by @sep@.

186+uivecSepBy :: (Syntax syn, VU.Unbox a) => syn Int (Int, a)

187+ -> syn () () -> syn Int (VU.Vector a)

188+uivecSepBy e sep = sibind $ iso (\n -> constant n #>> uivecNSepBy n e sep)

189+ (\v -> constant (VU.length v)

190+ #>> uivecNSepBy (VU.length v) e sep)

Data/Syntax/Indent.hs+5−4

@@ -10,7 +10,7 @@ License : MIT

10Maintainer : Paweł Nowak <pawel834@gmail.com>

11Stability : experimental

13−Provides a very simple indentation as a category transformer (a functor from Cat to Cat).

13+Provides a very simple indentation as a category transformer.

14-}

15module Data.Syntax.Indent (

16 Indent,

@@ -21,6 +21,7 @@ module Data.Syntax.Indent (

22import Control.Category

23import Control.Category.Reader

24+import Control.Category.Structures

24import Control.SIArrow

25import Control.SIArrow

25import Data.Syntax

26import Data.Syntax

26import Data.Syntax.Char

27import Data.Syntax.Char

@@ -28,10 +29,10 @@ import Data.Syntax.Combinator

28import Prelude hiding (takeWhile, take, id, (.))

29import Prelude hiding (takeWhile, take, id, (.))

30-- | Adds indentation to a syntax description.

31-- | Adds indentation to a syntax description.

31−newtype Indent cat a b = Indent { unIndent :: ReaderCT (Int, cat () ()) cat a b }

32+newtype Indent cat a b = Indent { getIndent :: ReaderCT (Int, cat () ()) cat a b }

32− deriving (Category, Products, Coproducts, CategoryPlus, SIArrow)

33+ deriving (Category, Products, Coproducts, CatPlus, SIArrow)

34−instance CategoryTrans Indent where

35+instance CatTrans Indent where

35 clift = Indent . clift

36 clift = Indent . clift

37-- Generalized newtype deriving cannot derive this :(

38-- Generalized newtype deriving cannot derive this :(

syntax.cabal+22−20

@@ -1,33 +1,35 @@

1name: syntax

2version: 1.0.0.0

3−synopsis: Syntax descriptions for unified parsing and pretty-printing.

3+synopsis: Reversible parsing and pretty-printing.

4description:

5− 'syntax' allows you to write a single syntax description and instantiate is both as a parser and a pretty printer.

5+ "syntax" allows you to write a single syntax description and instantiate is both as a parser and a pretty printer.

6 .

7− The interface is based on a custom Functor\/Applicative\/Monad hierarchy, provided by the 'semi-iso' package. You fmap using

7+ Syntax descriptions are written in applicative or arrow style. The library uses a custom typeclass hierarchy, provided

8− a semi-isomorphism instead of function. A semi-isomorphism is a isomorphism that can fail in both directions, with slightly

8+ by the "semi-iso" package. Most of the time you will be using operators like '/$/', '/*/' and '/+/' (= '<|>'), just

9− weakened laws. It is worth to note that @Iso@s and @Prism@s from 'lens' are valid semi-isomorphisms :)

9+ like parser combinators. When more power is needed - e.g. when the syntax depends on the parsed or printed value -

10+ you turn to arrows.

10 .

11 .

11− Once you write a description you can, for example turn it into an Attoparsec parser, or into a 'Data.Syntax.Printer.Text.Printer'.

12+ Semi-isomorphisms from "semi-iso" are the basic building block of syntax descriptions. I recommend reading

13+ the hackage page of "semi-iso" first, as it contains much more information.

12 .

14 .

13− See @syntax-example@ and @syntax-example-json@ for examples, @syntax-attoparsec@ and @syntax-printer@ for a parser/printer implementation.

15+ Once you write a syntax description (polymorphic in the syntax category) you can instantiate it both as a parser or as

16+ a pretty-printer. The library "syntax-attoparsec" gives you the ability to extract an Attoparsec parser. Pretty-printing

17+ is implemented by the "syntax-printer" library, which uses Text and ByteString builders. (Note that formatting is handled

18+ by "syntax" itself, not by the printer library)

14 .

19 .

15− The library was inspired by:

20+ Advanced formatting and parsing (for example indentation, haskell layout rule) is implemented as category transformers

21+ (similar to monad transformers). Currently only simple indentation is implemented (in "Data.Syntax.Indent") - basically

22+ a reader category transformer that tracks current indentation level. I plan on implementing Haskell layout rule in the

23+ future.

16 .

24 .

17− * Rendel, Tillmann, and Klaus Ostermann. "Invertible syntax descriptions: unifying parsing and pretty printing." ACM Sigplan Notices. Vol. 45. No. 11. ACM, 2010.

25+ The library can work with both text and binary data. Alas, there are no binary combinators implemented yet.

26+ I will implement them when i have the time (but these category transformers look so much more interesting for now ;).

18 .

27 .

19− TODO:

28+ EXAMPLES! See @syntax-example@ and @syntax-example-json@ for examples.

20 .

29 .

21− * Research relative monads and relative monad transformers. Indent is basically a Reader monad over a syntax. How would a State monad look?

30+ * "syntax-example" implements a simple lambda calculus.

22 .

31 .

23− * Try to implement Haskell layout rule.

32+ * "syntax-example-json" implements a json parser and pretty printer.

24− .

25− * Combinators for binary data formats, vectors.

26− .

27− * Better error messages.

28− .

29− * Maybe an implementation of do notation for SemiIsoMonad with QuasiQuoters, like the codo notation for comonads.

30−

31license: MIT

33license: MIT

32license-file: LICENSE

34license-file: LICENSE

33author: Paweł Nowak

35author: Paweł Nowak

@@ -46,5 +48,5 @@ library

46 Data.Syntax.Char

48 Data.Syntax.Char

47 Data.Syntax.Combinator

49 Data.Syntax.Combinator

48 Data.Syntax.Indent

50 Data.Syntax.Indent

49− build-depends: base >= 4 && < 5, mono-traversable, lens >= 4, semi-iso >= 1.0.0.0, scientific >= 0.3, text

51+ build-depends: base >= 4 && < 5, mono-traversable, lens >= 4, semi-iso >= 1, scientific >= 0.3, text, vector

50 default-language: Haskell2010

52 default-language: Haskell2010