From e126be20b38b891405e443b9ea16842840ea202b Mon Sep 17 00:00:00 2001
From: Maximilian Algehed <m.algehed@gmail.com>
Date: Thu, 21 Mar 2024 11:51:19 +0100
Subject: [PATCH] Function instances

---
 src/Test/QuickCheck/Arbitrary.hs |  1 -
 src/Test/QuickCheck/Function.hs  | 21 +++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/Test/QuickCheck/Arbitrary.hs b/src/Test/QuickCheck/Arbitrary.hs
index 9f4cee23..2ddfb7f7 100644
--- a/src/Test/QuickCheck/Arbitrary.hs
+++ b/src/Test/QuickCheck/Arbitrary.hs
@@ -1439,7 +1439,6 @@ instance CoArbitrary a => CoArbitrary (NonEmpty a) where
 #endif
 #endif
 
-
 #ifndef NO_FIXED
 instance HasResolution a => CoArbitrary (Fixed a) where
   coarbitrary = coarbitraryReal
diff --git a/src/Test/QuickCheck/Function.hs b/src/Test/QuickCheck/Function.hs
index d8c0d27f..f2ef5f89 100644
--- a/src/Test/QuickCheck/Function.hs
+++ b/src/Test/QuickCheck/Function.hs
@@ -72,6 +72,7 @@ import Data.Char
 import Data.Word
 import Data.List( intersperse )
 import Data.Ratio
+import Data.Ord
 import qualified Data.IntMap as IntMap
 import qualified Data.IntSet as IntSet
 import qualified Data.Map as Map
@@ -101,6 +102,12 @@ import Data.Fixed
 import GHC.Generics hiding (C)
 #endif
 
+#if defined(MIN_VERSION_base)
+#if MIN_VERSION_base(4,9,0)
+import Data.List.NonEmpty (NonEmpty(..))
+#endif
+#endif
+
 --------------------------------------------------------------------------
 -- concrete functions
 
@@ -261,6 +268,13 @@ instance Function a => Function [a] where
     h (Left _)       = []
     h (Right (x,xs)) = x:xs
 
+#if defined(MIN_VERSION_base)
+#if MIN_VERSION_base(4,9,0)
+instance Function a => Function (NonEmpty a) where
+  function = functionMap (\(a :| as) -> (a, as)) (uncurry (:|))
+#endif
+#endif
+
 instance Function a => Function (Maybe a) where
   function = functionMap g h
    where
@@ -423,6 +437,13 @@ instance Function a => Function (Monoid.First a) where
 instance Function a => Function (Monoid.Last a) where
   function = functionMap Monoid.getLast Monoid.Last
 
+#if defined(MIN_VERSION_base)
+#if MIN_VERSION_base(4,6,0)
+instance Function a => Function (Down a) where
+  function = functionMap (\(Down a) -> a) Down
+#endif
+#endif
+
 #if MIN_VERSION_base(4,8,0)
 instance Function (f a) => Function (Monoid.Alt f a) where
   function = functionMap Monoid.getAlt Monoid.Alt