Clean up as patterns in code

This ensures that yet-to-be-released GHC 9.0 and 9.2 can build Alex.

Author: Ericson2314

src/AbsSyn.hs

@@ -324,9 +324,9 @@ extractActions scheme scanner = (scanner{scannerTokens = new_tokens}, decl_str)
  where
   (new_tokens, decls) = unzip (zipWith f (scannerTokens scanner) act_names)
 
-  f r@RECtx{ reCtxCode = Just code } name
+  f r@(RECtx{ reCtxCode = Just code }) name
         = (r{reCtxCode = Just name}, Just (mkDecl name code))
-  f r@RECtx{ reCtxCode = Nothing } _
+  f r@(RECtx{ reCtxCode = Nothing }) _
         = (r{reCtxCode = Nothing}, Nothing)
 
   gscanActionType res =

src/DFAMin.hs

@@ -32,9 +32,9 @@ import Data.List as List
 -- end;
 
 minimizeDFA :: Ord a => DFA Int a -> DFA Int a
-minimizeDFA  dfa@ DFA { dfa_start_states = starts,
-                        dfa_states       = statemap
-                      }
+minimizeDFA dfa@(DFA { dfa_start_states = starts,
+                       dfa_states       = statemap
+                     })
   = DFA { dfa_start_states = starts,
           dfa_states       = Map.fromList states }
   where