From dfb16bf1dccc1afc8c503bf1d9d80d7df5ef6c87 Mon Sep 17 00:00:00 2001
From: Andrew Martin <andrew.thaddeus@gmail.com>
Date: Sat, 2 Nov 2024 13:43:17 -0400
Subject: [PATCH] Add equals# for Fin#

---
 src/Arithmetic/Fin.hs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/Arithmetic/Fin.hs b/src/Arithmetic/Fin.hs
index 447daeb..84e68dc 100644
--- a/src/Arithmetic/Fin.hs
+++ b/src/Arithmetic/Fin.hs
@@ -65,6 +65,9 @@ module Arithmetic.Fin
   , fromInt#
   , constant#
 
+    -- * Compare
+  , equals#
+
     -- * Lift and Unlift
   , lift
   , unlift
@@ -75,7 +78,7 @@ import Prelude hiding (last, succ)
 import Arithmetic.Nat ((<?))
 import Arithmetic.Types (Difference (..), Fin (..), Nat, Nat#, pattern MaybeFinJust#, pattern MaybeFinNothing#, type (:=:), type (<), type (<#), type (<=))
 import Arithmetic.Unsafe (Fin# (Fin#), MaybeFin#, Nat# (Nat#))
-import GHC.Exts (Int (I#), Int#, Word#, (+#))
+import GHC.Exts (Int (I#), Int#, Word#, (+#), (==#))
 import GHC.TypeNats (CmpNat, type (+))
 
 import qualified Arithmetic.Equal as Eq
@@ -610,3 +613,6 @@ type applications to clarify when it is helpful. For example:
 -}
 constant# :: forall (b :: GHC.Nat) (a :: GHC.Nat). (CmpNat a b ~ 'LT) => Nat# a -> Fin# b
 constant# (Nat# i) = Fin# i
+
+equals# :: Fin# n -> Fin# n -> Bool
+equals# (Fin# a) (Fin# b) = Exts.isTrue# (a ==# b)