5ca9205 · ormolu · git.iko.soy

git.iko.soy/ormolu

Take non-commutative nature of language pragmas into account

The order in which language pragmas are put in the input sometimes matters. This is because some language extensions can enable other extensions, yet the extensions coming later in the list have the ability to change it. So here we classify all extensions by assigning one of the four groups to them. Then we only sort inside of the groups.

commit5ca92059fb59e891ac36b3abf735d242b28f50dc authormrkkrp <mark.karpov@tweag.io> dateThu 28 Nov 2019, 16:30 (7 years ago) parent6e07126

5 files changed+73−4

compare with master

unifiedsplit

CHANGELOG.md+3 data/examples/declaration/class/type-operators3-out.hs+1−1 data/examples/other/pragma-sorting-out.hs+12 data/examples/other/pragma-sorting.hs+10 src/Ormolu/Printer/Meat/Pragma.hs+47−3

CHANGELOG.md+3

@@ -38,6 +38,9 @@

3838* Implemented correct handling of stack headers. [Issue

3939 393](https://github.com/tweag/ormolu/issues/393).

4040

41+* Sorting language pragmas cannot not change meaning of the input program

42+ anymore. [Issue 404](https://github.com/tweag/ormolu/issues/404).

43+

4144## Ormolu 0.0.1.0

4245

4346* Initial release.

data/examples/declaration/class/type-operators3-out.hs+1−1

@@ -1,7 +1,7 @@

1−{-# LANGUAGE NoStarIsType #-}

21{-# LANGUAGE PolyKinds #-}

32{-# LANGUAGE TypeFamilies #-}

43{-# LANGUAGE TypeOperators #-}

4+{-# LANGUAGE NoStarIsType #-}

66class PNum x where

77 type (a :: x) * (b :: x)

data/examples/other/pragma-sorting-out.hsnew file+12

@@ -0,0 +1,12 @@

1+{-# LANGUAGE NondecreasingIndentation #-}

2+{-# LANGUAGE ScopedTypeVariables #-}

3+{-# LANGUAGE TypeFamilies #-}

4+{-# LANGUAGE NoMonoLocalBinds #-}

6+-- This gap is necessary for stylish Haskell not to re-arrange

7+-- NoMonoLocalBinds before TypeFamilies

9+module Foo

10+ ( bar,

11+ )

12+where

data/examples/other/pragma-sorting.hsnew file+10

@@ -0,0 +1,10 @@

1+{-# LANGUAGE ScopedTypeVariables #-}

2+{-# LANGUAGE TypeFamilies #-}

3+{-# LANGUAGE NondecreasingIndentation #-}

4+-- This gap is necessary for stylish Haskell not to re-arrange

5+-- NoMonoLocalBinds before TypeFamilies

6+{-# LANGUAGE NoMonoLocalBinds #-}

8+module Foo (

9+ bar

10+ ) where

src/Ormolu/Printer/Meat/Pragma.hs+47−3

@@ -8,18 +8,46 @@ module Ormolu.Printer.Meat.Pragma

88 )

99where

1010

11+import Data.Char (isUpper)

12+import Data.Maybe (listToMaybe)

1113import qualified Data.Set as S

1214import qualified Data.Text as T

1315import Ormolu.Parser.Pragma (Pragma (..))

1416import Ormolu.Printer.Combinators

1517

16−data PragmaTy = Language | OptionsGHC | OptionsHaddock

18+-- | Pragma classification.

19+data PragmaTy

20+ = Language LanguagePragmaClass

21+ | OptionsGHC

22+ | OptionsHaddock

23+ deriving (Eq, Ord)

24+

25+-- | Language pragma classification.

26+--

27+-- The order in which language pragmas are put in the input sometimes

28+-- matters. This is because some language extensions can enable other

29+-- extensions, yet the extensions coming later in the list have the ability

30+-- to change it. So here we classify all extensions by assigning one of the

31+-- four groups to them. Then we only sort inside of the groups.

32+--

33+-- 'Ord' instance of this data type is what affects the sorting.

34+--

35+-- See also: <https://github.com/tweag/ormolu/issues/404>

36+data LanguagePragmaClass

37+ = -- | All other extensions

38+ Normal

39+ | -- | Extensions starting with "No"

40+ Disabling

41+ | -- | Extensions that should go after everything else

42+ Final

1743 deriving (Eq, Ord)

1844

1945p_pragmas :: [Pragma] -> R ()

2046p_pragmas ps =

2147 let prepare = concatMap $ \case

22− PragmaLanguage xs -> (Language,) <$> xs

48+ PragmaLanguage xs ->

49+ let f x = (Language (classifyLanguagePragma x), x)

50+ in f <$> xs

2351 PragmaOptionsGHC x -> [(OptionsGHC, x)]

2452 PragmaOptionsHaddock x -> [(OptionsHaddock, x)]

2553 in mapM_ (uncurry p_pragma) (S.toAscList . S.fromList . prepare $ ps)

@@ -28,10 +56,26 @@ p_pragma :: PragmaTy -> String -> R ()

2856p_pragma ty c = do

2957 txt "{-# "

3058 txt $ case ty of

31− Language -> "LANGUAGE"

59+ Language _ -> "LANGUAGE"

3260 OptionsGHC -> "OPTIONS_GHC"

3361 OptionsHaddock -> "OPTIONS_HADDOCK"

3462 space

3563 txt (T.pack c)

3664 txt " #-}"

3765 newline

66+

67+-- | Classify a 'LanguagePragma'.

68+classifyLanguagePragma :: String -> LanguagePragmaClass

69+classifyLanguagePragma = \case

70+ "ImplicitPrelude" -> Final

71+ "CUSKs" -> Final

72+ str ->

73+ case splitAt 2 str of

74+ ("No", rest) ->

75+ case listToMaybe rest of

76+ Nothing -> Normal

77+ Just x ->

78+ if isUpper x

79+ then Disabling

80+ else Normal

81+ _ -> Normal