Value.Equal: refactor

Author: Anton-Latukha

src/Nix/Value/Equal.hs

@@ -30,18 +30,21 @@ import           Nix.Utils
 import           Nix.Value
 
 checkComparable
-  :: (Framed e m, MonadDataErrorContext t f m)
+  :: ( Framed e m
+     , MonadDataErrorContext t f m
+     )
   => NValue t f m
   -> NValue t f m
   -> m ()
-checkComparable x y = case (x, y) of
-  (NVConstant (NFloat _), NVConstant (NInt _)) -> pure ()
-  (NVConstant (NInt _), NVConstant (NFloat _)) -> pure ()
-  (NVConstant (NInt _), NVConstant (NInt _)) -> pure ()
-  (NVConstant (NFloat _), NVConstant (NFloat _)) -> pure ()
-  (NVStr _, NVStr _) -> pure ()
-  (NVPath _, NVPath _) -> pure ()
-  _ -> throwError $ Comparison x y
+checkComparable x y =
+  case (x, y) of
+    (NVConstant (NFloat _), NVConstant (NInt   _)) -> pure ()
+    (NVConstant (NInt   _), NVConstant (NFloat _)) -> pure ()
+    (NVConstant (NInt   _), NVConstant (NInt   _)) -> pure ()
+    (NVConstant (NFloat _), NVConstant (NFloat _)) -> pure ()
+    (NVStr       _        , NVStr       _        ) -> pure ()
+    (NVPath      _        , NVPath      _        ) -> pure ()
+    _                                              -> throwError $ Comparison x y
 
 -- | Checks whether two containers are equal, using the given item equality
 --   predicate. If there are any item slots that don't match between the two
@@ -52,16 +55,22 @@ alignEqM
   -> f a
   -> f b
   -> m Bool
-alignEqM eq fa fb = fmap (either (const False) (const True)) $ runExceptT $
-  do
-    pairs <-
-      traverse
-        (\case
-          These a b -> pure (a, b)
-          _         -> throwE ()
-        )
-        (Data.Align.align fa fb)
-    traverse_ (\ (a, b) -> guard =<< lift (eq a b)) pairs
+alignEqM eq fa fb =
+  fmap
+    (either
+      (const False)
+      (const True)
+    )
+    $ runExceptT $
+      do
+        pairs <-
+          traverse
+            (\case
+              These a b -> pure (a, b)
+              _         -> throwE ()
+            )
+            (Data.Align.align fa fb)
+        traverse_ (\ (a, b) -> guard =<< lift (eq a b)) pairs
 
 alignEq :: (Align f, Traversable f) => (a -> b -> Bool) -> f a -> f b -> Bool
 alignEq eq fa fb = runIdentity $ alignEqM (\x y -> Identity (eq x y)) fa fb
@@ -114,13 +123,13 @@ valueFEqM
 valueFEqM attrsEq eq =
   curry $
     \case
-      (NVConstantF (NFloat x), NVConstantF (NInt   y)) -> pure $ x == fromInteger y
+      (NVConstantF (NFloat x), NVConstantF (NInt   y)) -> pure $             x == fromInteger y
       (NVConstantF (NInt   x), NVConstantF (NFloat y)) -> pure $ fromInteger x == y
-      (NVConstantF lc        , NVConstantF rc        ) -> pure $ lc == rc
-      (NVStrF      ls        , NVStrF      rs        ) -> pure $ (\i -> i ls == i rs) stringIgnoreContext
-      (NVListF     ls        , NVListF     rs        ) -> alignEqM eq ls rs
-      (NVSetF      lm _      , NVSetF      rm _      ) -> attrsEq lm rm
-      (NVPathF     lp        , NVPathF     rp        ) -> pure $ lp == rp
+      (NVConstantF lc        , NVConstantF rc        ) -> pure $            lc == rc
+      (NVStrF      ls        , NVStrF      rs        ) -> pure $  (\ i -> i ls == i rs) stringIgnoreContext
+      (NVListF     ls        , NVListF     rs        ) ->          alignEqM eq ls rs
+      (NVSetF      lm _      , NVSetF      rm _      ) ->          attrsEq lm rm
+      (NVPathF     lp        , NVPathF     rp        ) ->             pure $ lp == rp
       _                                                -> pure False
 
 valueFEq
@@ -179,9 +188,13 @@ valueEqM
   -> m Bool
 valueEqM (  Pure x) (  Pure y) = thunkEqM x y
 valueEqM (  Pure x) y@(Free _) = thunkEqM x =<< thunk (pure y)
-valueEqM x@(Free _) (  Pure y) = thunkEqM ?? y =<< thunk (pure x)
+valueEqM x@(Free _) (  Pure y) = (`thunkEqM` y) =<< thunk (pure x)
 valueEqM (Free (NValue (extract -> x))) (Free (NValue (extract -> y))) =
-  valueFEqM (compareAttrSetsM f valueEqM) valueEqM x y
+  valueFEqM
+    (compareAttrSetsM f valueEqM)
+    valueEqM
+    x
+    y
  where
   f =
     free