From ffaba28677908d722247ddbb481d04d69fc99717 Mon Sep 17 00:00:00 2001
From: Patrick Thomson <patrickt@github.com>
Date: Wed, 27 Mar 2019 09:03:49 -0400
Subject: [PATCH] Fix tests.

---
 src/Data/Flag.hs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/Data/Flag.hs b/src/Data/Flag.hs
index e74a5a00b..785d369cd 100644
--- a/src/Data/Flag.hs
+++ b/src/Data/Flag.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE RankNTypes, KindSignatures #-}
+{-# LANGUAGE DerivingStrategies, GeneralizedNewtypeDeriving, RankNTypes, KindSignatures #-}
 
 -- | -- This technique is due to Oleg Grenrus: <http://oleg.fi/gists/posts/2019-03-21-flag.html>
 -- The implementation is clean-room due to unclear licensing of the original post.
@@ -10,7 +10,7 @@ module Data.Flag
   , choose
   ) where
 
-import Data.Coerce
+import Prologue
 
 -- | To declare a new flag, declare a singly-inhabited type:
 -- @data MyFlag = MyFlag@
@@ -19,6 +19,8 @@ import Data.Coerce
 -- working with multiple flag values in flight, as the 'toBool' deconstructor provides a witness
 -- that you really want the given semantic flag value from the flag datum.
 newtype Flag (t :: *) = Flag Bool
+  deriving stock (Eq, Show)
+  deriving newtype NFData
 
 -- | The constructor for a 'Flag'. You specify @t@ with a visible type application.
 flag :: t -> Bool -> Flag t