Add various instances for NullOrUndefined (#52)

* Derive more instances for `NullOrUndefined` et. al

* Wrap `show` output in parenthesis

* Remove Data.Function import

Author: felixSchl

src/Data/Foreign/Null.purs

@@ -3,6 +3,7 @@ module Data.Foreign.Null where
 import Prelude
 
 import Data.Maybe (Maybe(..))
+import Data.Newtype (class Newtype, unwrap)
 import Data.Foreign (F, Foreign, isNull)
 
 -- | A `newtype` wrapper whose `IsForeign` instance correctly handles
@@ -12,6 +13,13 @@ import Data.Foreign (F, Foreign, isNull)
 -- | but not `undefined`.
 newtype Null a = Null (Maybe a)
 
+derive instance newtypeNull :: Newtype (Null a) _
+derive instance eqNull :: (Eq a) => Eq (Null a)
+derive instance ordNull :: (Ord a) => Ord (Null a)
+
+instance showNull :: (Show a) => Show (Null a) where
+  show x = "(Null " <> show (unwrap x) <> ")"
+
 -- | Unwrap a `Null` value
 unNull :: forall a. Null a -> Maybe a
 unNull (Null m) = m

src/Data/Foreign/NullOrUndefined.purs

@@ -2,6 +2,7 @@ module Data.Foreign.NullOrUndefined where
 
 import Prelude
 
+import Data.Newtype (class Newtype, unwrap)
 import Data.Maybe (Maybe(..))
 import Data.Foreign (F, Foreign, isUndefined, isNull)
 
@@ -12,6 +13,13 @@ import Data.Foreign (F, Foreign, isUndefined, isNull)
 -- | or `undefined`.
 newtype NullOrUndefined a = NullOrUndefined (Maybe a)
 
+derive instance newtypeNullOrUndefined :: Newtype (NullOrUndefined a) _
+derive instance eqNullOrUndefined :: (Eq a) => Eq (NullOrUndefined a)
+derive instance ordNullOrUndefined :: (Ord a) => Ord (NullOrUndefined a)
+
+instance showNullOrUndefined :: (Show a) => Show (NullOrUndefined a) where
+  show x = "(NullOrUndefined " <> show (unwrap x) <> ")"
+
 -- | Unwrap a `NullOrUndefined` value
 unNullOrUndefined :: forall a. NullOrUndefined a -> Maybe a
 unNullOrUndefined (NullOrUndefined m) = m

src/Data/Foreign/Undefined.purs

@@ -3,6 +3,7 @@ module Data.Foreign.Undefined where
 import Prelude
 
 import Data.Maybe (Maybe(..))
+import Data.Newtype (class Newtype, unwrap)
 import Data.Foreign (F, Foreign, isUndefined)
 
 -- | A `newtype` wrapper whose `IsForeign` instance correctly handles
@@ -12,6 +13,13 @@ import Data.Foreign (F, Foreign, isUndefined)
 -- | but not `null`.
 newtype Undefined a = Undefined (Maybe a)
 
+derive instance newtypeUndefined :: Newtype (Undefined a) _
+derive instance eqUndefined :: (Eq a) => Eq (Undefined a)
+derive instance ordUndefined :: (Ord a) => Ord (Undefined a)
+
+instance showUndefined :: (Show a) => Show (Undefined a) where
+  show x = "(Undefined " <> show (unwrap x) <> ")"
+
 -- | Unwrap an `Undefined` value
 unUndefined :: forall a. Undefined a -> Maybe a
 unUndefined (Undefined m) = m