classify operator symbols like haskell-src-exts does

Author: phischu

src/Language/Haskell/Names/SyntaxUtils.hs

@@ -21,12 +21,13 @@ module Language.Haskell.Names.SyntaxUtils
     -- export ExtensionSet here for the outside users
   , ExtensionSet
   , moduleExtensions
+  , getModuleExtensions
   ) where
 import Prelude hiding (concatMap)
 import Data.Char
 import Data.Maybe
 import Data.Either
-import Data.Foldable
+import Data.Foldable hiding (elem)
 import qualified Data.Set as Set
 import qualified Language.Haskell.Exts as UnAnn
 import Language.Haskell.Exts.Annotated
@@ -123,9 +124,14 @@ nameToString (Ident _ s) = s
 nameToString (Symbol _ s) = s
 
 stringToName :: String -> Name ()
-stringToName s@(c:_) | isSymbol c = Symbol () s
+stringToName s@(c:_) | isHSymbol c = Symbol () s
 stringToName s = Ident () s
 
+isHSymbol :: Char -> Bool
+isHSymbol c =
+  c `elem` ":!#%&*./?@\\-" ||
+  ((isSymbol c || isPunctuation c) && not (c `elem` "(),;[]`{}_\"'"))
+
 specialConToString :: SpecialCon l -> String
 specialConToString (UnitCon _)            = "()"
 specialConToString (ListCon _)            = "[]"