Can add new language pragmas if necessary

4 files changed, 32 insertions, 7 deletions

diff --git a/.stylish-haskell.yaml b/.stylish-haskell.yaml
index 8316895..66683ac 100644
--- a/.stylish-haskell.yaml
+++ b/.stylish-haskell.yaml
@@ -1,3 +1,5 @@
+unicode_syntax: {}
+
 # Import cleanup
 imports:
     # Align import names and import lists
diff --git a/src/StylishHaskell/Config.hs b/src/StylishHaskell/Config.hs
index 2d9617f..c4eefa7 100644
--- a/src/StylishHaskell/Config.hs
+++ b/src/StylishHaskell/Config.hs
@@ -27,6 +27,7 @@ import qualified StylishHaskell.Stylish.Imports
 import qualified StylishHaskell.Stylish.LanguagePragmas
 import qualified StylishHaskell.Stylish.Tabs
 import qualified StylishHaskell.Stylish.TrailingWhitespace
+import qualified StylishHaskell.Stylish.UnicodeSyntax
 
 
 --------------------------------------------------------------------------------
@@ -100,6 +101,7 @@ parseConfig (A.Object o) = Config . catMaybes <$> sequence
     , optional o "languages_pragmas"   parseLanguagePragmas
     , optional o "tabs"                parseTabs
     , optional o "trailing_whitespace" parseTrailingWhitespace
+    , optional o "unicode_syntax"      parseUnicodeSyntax
     ]
 parseConfig _            = mzero
 
@@ -125,3 +127,8 @@ parseTabs o = StylishHaskell.Stylish.Tabs.stylish
 parseTrailingWhitespace :: A.Object -> A.Parser Stylish
 parseTrailingWhitespace _ =
     return StylishHaskell.Stylish.TrailingWhitespace.stylish
+
+
+--------------------------------------------------------------------------------
+parseUnicodeSyntax :: A.Object -> A.Parser Stylish
+parseUnicodeSyntax _ = return StylishHaskell.Stylish.UnicodeSyntax.stylish
diff --git a/src/StylishHaskell/Stylish/LanguagePragmas.hs b/src/StylishHaskell/Stylish/LanguagePragmas.hs
index c819050..f4da813 100644
--- a/src/StylishHaskell/Stylish/LanguagePragmas.hs
+++ b/src/StylishHaskell/Stylish/LanguagePragmas.hs
@@ -1,6 +1,9 @@
 --------------------------------------------------------------------------------
 module StylishHaskell.Stylish.LanguagePragmas
     ( stylish
+
+      -- * Utilities
+    , addLanguagePragma
     ) where
 
 
@@ -51,3 +54,15 @@ stylish ls (module', _)
     uniques  = nub $ sort $ concatMap snd pragmas'
     loc      = firstLocation pragmas'
     changes  = insert loc (prettyPragmas uniques) : deletes
+
+
+--------------------------------------------------------------------------------
+-- | Add a LANGUAGE pragma to a module if it is not present already.
+addLanguagePragma :: String -> H.Module H.SrcSpanInfo -> [Change String]
+addLanguagePragma pragma modu
+    | pragma `elem` present = []
+    | otherwise             = [insert line ["{-# LANGUAGE " ++ pragma ++ "#-}"]]
+  where
+    pragmas' = pragmas (fmap linesFromSrcSpan modu)
+    present  = concatMap snd pragmas'
+    line     = if null pragmas' then 1 else firstLocation pragmas'
diff --git a/src/StylishHaskell/Stylish/UnicodeSyntax.hs b/src/StylishHaskell/Stylish/UnicodeSyntax.hs
index 308c15b..7ed96e3 100644
--- a/src/StylishHaskell/Stylish/UnicodeSyntax.hs
+++ b/src/StylishHaskell/Stylish/UnicodeSyntax.hs
@@ -1,22 +1,23 @@
 --------------------------------------------------------------------------------
-{-# LANGUAGE UnicodeSyntax #-}
+{-# LANGUAGE ViewPatterns #-}
 module StylishHaskell.Stylish.UnicodeSyntax
     ( stylish
     ) where
 
 
 --------------------------------------------------------------------------------
-import           Data.List                       (isPrefixOf, sort)
-import           Data.Map                        (Map)
-import qualified Data.Map                        as M
-import           Data.Maybe                      (maybeToList)
-import qualified Language.Haskell.Exts.Annotated as H
+import           Data.List                              (isPrefixOf, sort)
+import           Data.Map                               (Map)
+import qualified Data.Map                               as M
+import           Data.Maybe                             (maybeToList)
+import qualified Language.Haskell.Exts.Annotated        as H
 
 
 --------------------------------------------------------------------------------
 import           StylishHaskell.Block
 import           StylishHaskell.Editor
 import           StylishHaskell.Stylish
+import           StylishHaskell.Stylish.LanguagePragmas (addLanguagePragma)
 import           StylishHaskell.Util
 
 
@@ -121,7 +122,7 @@ between (startRow, startCol) (endRow, endCol) needle =
 stylish :: Stylish
 stylish ls (module', _) = applyChanges changes ls
   where
-    changes = replaceAll perLine ls
+    changes = addLanguagePragma "UnicodeSyntax" module' ++ replaceAll perLine ls
     perLine = sort $ groupPerLine $
         typeSigs module' ls ++
         contexts module' ls ++