Make sorting deriving list optional (#316)

* Make sorting deriving list optional

Not everyone wants their typeclasses sorted.

* Remove redundant code

Co-authored-by: Łukasz Gołębiewski <lukasz.golebiewski@gmail.com>

2 files changed, 4 insertions, 1 deletions

diff --git a/lib/Language/Haskell/Stylish/Config.hs b/lib/Language/Haskell/Stylish/Config.hs
index 333736f..68638a6 100644
--- a/lib/Language/Haskell/Stylish/Config.hs
+++ b/lib/Language/Haskell/Stylish/Config.hs
@@ -221,6 +221,7 @@ parseRecords c o = Data.step
         <*> (o A..:? "break_single_constructors" A..!= True)
         <*> (o A..: "via" >>= parseIndent)
         <*> (o A..:? "curried_context" A..!= False)
+        <*> (o A..:? "sort_deriving" A..!= True)
         <*> pure configMaxColumns)
   where
     configMaxColumns =
diff --git a/lib/Language/Haskell/Stylish/Step/Data.hs b/lib/Language/Haskell/Stylish/Step/Data.hs
index bf39c7c..523389b 100644
--- a/lib/Language/Haskell/Stylish/Step/Data.hs
+++ b/lib/Language/Haskell/Stylish/Step/Data.hs
@@ -71,6 +71,8 @@ data Config = Config
       -- ^ Indentation between @via@ clause and start of deriving column start
     , cCurriedContext          :: !Bool
       -- ^ If true, use curried context. E.g: @allValues :: Enum a => Bounded a => Proxy a -> [a]@
+    , cSortDeriving            :: !Bool
+      -- ^ If true, will sort type classes in a @deriving@ list.
     , cMaxColumns              :: !MaxColumns
     } deriving (Show)
 
@@ -266,7 +268,7 @@ putDeriving Config{..} (L pos clause) = do
       = clause
       & deriv_clause_tys
       & unLocated
-      & sortBy compareOutputable
+      & (if cSortDeriving then sortBy compareOutputable else id)
       & fmap hsib_body
 
     headTy =