Remove redundant contexts from Foldable methods

New `Foldable` methods accidentally had `Foldable` contexts, which led
to type roles being assigned incorrectly and preventing GND from
deriving `Foldable` instances. Removing those fixes #9761.

Moreover, this patch takes advantage of this fix by deriving
`Foldable` (and `Eq`) for `UniqFM`.

Differential Revision: https://phabricator.haskell.org/D425

1 files changed, 3 insertions, 17 deletions

diff --git a/compiler/utils/UniqFM.lhs b/compiler/utils/UniqFM.lhs
index 3ea97e467c..f0f903522b 100644
--- a/compiler/utils/UniqFM.lhs
+++ b/compiler/utils/UniqFM.lhs
@@ -72,7 +72,6 @@ import Outputable
 
 import Compiler.Hoopl   hiding (Unique)
 
-import Data.Function (on)
 import qualified Data.IntMap as M
 import qualified Data.IntSet as S
 import qualified Data.Foldable as Foldable
@@ -212,22 +211,9 @@ instance Monoid (UniqFM a) where
 %************************************************************************
 
 \begin{code}
-newtype UniqFM ele = UFM { unUFM :: M.IntMap ele }
-  deriving (Typeable,Data, Traversable.Traversable, Functor)
-
-instance Eq ele => Eq (UniqFM ele) where
-    (==) = (==) `on` unUFM
-
-{-
-instance Functor UniqFM where
-   fmap f = fmap f . unUFM
-
-instance Traversable.Traversable UniqFM where
-    traverse f = Traversable.traverse f . unUFM
--}
-
-instance Foldable.Foldable UniqFM where
-    foldMap f = Foldable.foldMap f . unUFM
+newtype UniqFM ele = UFM (M.IntMap ele)
+  deriving (Data, Eq, Foldable.Foldable, Functor, Traversable.Traversable,
+            Typeable)
 
 emptyUFM = UFM M.empty
 isNullUFM (UFM m) = M.null m