Derive various instances for NullOrUndefined

Author: felixSchl

src/Data/Foreign/NullOrUndefined.purs

@@ -2,6 +2,8 @@ module Data.Foreign.NullOrUndefined where
 
 import Prelude
 
+import Data.Function (on)
+import Data.Newtype (class Newtype, unwrap)
 import Data.Maybe (Maybe(..))
 import Data.Foreign (F, Foreign, isUndefined, isNull)
 
@@ -12,6 +14,17 @@ import Data.Foreign (F, Foreign, isUndefined, isNull)
 -- | or `undefined`.
 newtype NullOrUndefined a = NullOrUndefined (Maybe a)
 
+derive instance newtypeNullOrUndefined :: Newtype (NullOrUndefined a) _
+
+instance showNullOrUndefined :: (Show a) => Show (NullOrUndefined a) where
+  show x = "NullOrUndefined " <> show (unwrap x)
+
+instance eqNullOrUndefined :: (Eq a) => Eq (NullOrUndefined a) where
+  eq = eq `on` unwrap
+
+instance ordNullOrUndefined :: (Ord a) => Ord (NullOrUndefined a) where
+  compare = compare `on` unwrap
+
 -- | Unwrap a `NullOrUndefined` value
 unNullOrUndefined :: forall a. NullOrUndefined a -> Maybe a
 unNullOrUndefined (NullOrUndefined m) = m