Add a add_language_pragma option to UnicodeSyntax

5 files changed, 26 insertions, 15 deletions

diff --git a/.stylish-haskell.yaml b/.stylish-haskell.yaml
index 288d307..bfa8595 100644
--- a/.stylish-haskell.yaml
+++ b/.stylish-haskell.yaml
@@ -1,7 +1,19 @@
+# stylish-haskell configuration file
+# ==================================
+#
+# The stylish-haskell tool is mainly configured by specifying steps. These steps
+# are a list, so they have an order, and one specific step may appear more than
+# once (if needed). Each file is processed by these steps in the given order.
 steps:
   # Convert some ASCII sequences to their Unicode equivalents. This is disabled
   # by default.
-  # - unicode_syntax: {}
+  # - unicode_syntax:
+  #     # In order to make this work, we also need to insert the UnicodeSyntax
+  #     # language pragma. If this flag is set to true, we insert it when it's
+  #     # not already present. You may want to disable it if you configure
+  #     # language extensions using some other method than pragmas. Default:
+  #     # true.
+  #     add_language_pragma: true
 
   # Import cleanup
   - imports:
diff --git a/src/StylishHaskell/Config.hs b/src/StylishHaskell/Config.hs
index a2daaab..f305cc3 100644
--- a/src/StylishHaskell/Config.hs
+++ b/src/StylishHaskell/Config.hs
@@ -171,4 +171,5 @@ parseTrailingWhitespace _ = return TrailingWhitespace.step
 
 --------------------------------------------------------------------------------
 parseUnicodeSyntax :: A.Object -> A.Parser Step
-parseUnicodeSyntax _ = return UnicodeSyntax.step
+parseUnicodeSyntax o = UnicodeSyntax.step
+    <$> o A..:? "add_language_pragma" A..!= True
diff --git a/src/StylishHaskell/Step/LanguagePragmas.hs b/src/StylishHaskell/Step/LanguagePragmas.hs
index ed6d3b5..1f3ccb2 100644
--- a/src/StylishHaskell/Step/LanguagePragmas.hs
+++ b/src/StylishHaskell/Step/LanguagePragmas.hs
@@ -88,9 +88,9 @@ step' style removeRedundant ls (module', _)
 --------------------------------------------------------------------------------
 -- | 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 ++ "#-}"]]
+addLanguagePragma prag modu
+    | prag `elem` present = []
+    | otherwise           = [insert line ["{-# LANGUAGE " ++ prag ++ " #-}"]]
   where
     pragmas' = pragmas (fmap linesFromSrcSpan modu)
     present  = concatMap snd pragmas'
diff --git a/src/StylishHaskell/Step/UnicodeSyntax.hs b/src/StylishHaskell/Step/UnicodeSyntax.hs
index a43e4f5..c3290c7 100644
--- a/src/StylishHaskell/Step/UnicodeSyntax.hs
+++ b/src/StylishHaskell/Step/UnicodeSyntax.hs
@@ -119,15 +119,16 @@ between (startRow, startCol) (endRow, endCol) needle =
 
 
 --------------------------------------------------------------------------------
-step :: Step
-step = makeStep "UnicodeSyntax" step'
+step :: Bool -> Step
+step = makeStep "UnicodeSyntax" . step'
 
 
 --------------------------------------------------------------------------------
-step' :: Lines -> Module -> Lines
-step' ls (module', _) = applyChanges changes ls
+step' :: Bool -> Lines -> Module -> Lines
+step' alp ls (module', _) = applyChanges changes ls
   where
-    changes = addLanguagePragma "UnicodeSyntax" module' ++ replaceAll perLine ls
+    changes = (if alp then addLanguagePragma "UnicodeSyntax" module' else []) ++
+        replaceAll perLine ls
     perLine = sort $ groupPerLine $
         typeSigs module' ls ++
         contexts module' ls ++
diff --git a/tests/StylishHaskell/Step/UnicodeSyntax/Tests.hs b/tests/StylishHaskell/Step/UnicodeSyntax/Tests.hs
index 9f53b58..f7bd80a 100644
--- a/tests/StylishHaskell/Step/UnicodeSyntax/Tests.hs
+++ b/tests/StylishHaskell/Step/UnicodeSyntax/Tests.hs
@@ -24,18 +24,15 @@ tests = testGroup "StylishHaskell.Step.UnicodeSyntax.Tests"
 
 --------------------------------------------------------------------------------
 case01 :: Test
-case01 = testCase "case 01" $ expected @=? testStep step input
+case01 = testCase "case 01" $ expected @=? testStep (step True) input
   where
     input = unlines
-        [ "{-# LANGUAGE UnicodeSyntax #-}"  -- TODO: remove
-        , ""
-        , "sort :: Ord a => [a] -> [a]"
+        [ "sort :: Ord a => [a] -> [a]"
         , "sort _ = []"
         ]
 
     expected = unlines
         [ "{-# LANGUAGE UnicodeSyntax #-}"
-        , ""
         , "sort ∷ Ord a ⇒ [a] → [a]"
         , "sort _ = []"
         ]