Require Ord instead of Eq

Not used yet, but will be soon

src/Stan/Hie.hs

@@ -84,7 +84,7 @@ This function needs to take the original 'HieFile' because constants
 are not stored in 'HieAST' and to compare constants we need to compare
 parts of source code.
 -}
-eqAst :: forall a . Eq a => HieFile -> HieAST a -> HieAST a -> Bool
+eqAst :: forall a . Ord a => HieFile -> HieAST a -> HieAST a -> Bool
 eqAst HieFile{..} = eqNodes
   where
     eqNodes :: HieAST a -> HieAST a -> Bool

src/Stan/Hie/Compat900.hs

@@ -52,7 +52,7 @@ import Text.Show (show)
 -- 2. return a NodeInfo with empty fields when the SourceInfo is empty
 --
 -- It works though.
-nodeInfo :: HieAST a -> NodeInfo a
+nodeInfo :: Ord a => HieAST a -> NodeInfo a
 nodeInfo h = case (lookup' SourceInfo, lookup' GeneratedInfo) of
   (Nothing, Nothing) -> error "nodeInfo"
   (Just n1, Nothing) -> n1

src/Stan/Hie/Compat902.hs

@@ -51,7 +51,7 @@ import Text.Show (show)
 -- 2. return a NodeInfo with empty fields when the SourceInfo is empty
 --
 -- It works though.
-nodeInfo :: HieAST a -> NodeInfo a
+nodeInfo :: Ord a => HieAST a -> NodeInfo a
 nodeInfo h = case (lookup' SourceInfo, lookup' GeneratedInfo) of
   (Nothing, Nothing) -> error "nodeInfo"
   (Just n1, Nothing) -> n1

src/Stan/Hie/Compat904.hs

@@ -49,7 +49,7 @@ import Text.Show (show)
 -- 2. return a NodeInfo with empty fields when the SourceInfo is empty
 --
 -- It works though.
-nodeInfo :: HieAST a -> NodeInfo a
+nodeInfo :: Ord a => HieAST a -> NodeInfo a
 nodeInfo h = case (lookup' SourceInfo, lookup' GeneratedInfo) of
   (Nothing, Nothing) -> error "nodeInfo"
   (Just n1, Nothing) -> n1