From 793e306e5fce1519601f7f82dcd0cb9b7a28c13f Mon Sep 17 00:00:00 2001
From: Julien Moutinho <julm+symantic-base@sourcephile.fr>
Date: Sat, 11 Sep 2021 20:45:45 +0200
Subject: [PATCH] iface: add instance `Category Iso`
---
src/Symantic/Lang.hs | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/src/Symantic/Lang.hs b/src/Symantic/Lang.hs
index 1d76d16..47924b3 100644
--- a/src/Symantic/Lang.hs
+++ b/src/Symantic/Lang.hs
@@ -12,6 +12,7 @@ import Data.Kind (Type)
import Data.Maybe (Maybe(..), fromJust)
import Data.Proxy (Proxy(..))
import GHC.Generics (Generic)
+import qualified Control.Category as Cat
import qualified Data.Function as Fun
import qualified Data.Tuple as Tuple
@@ -167,6 +168,9 @@ class IsoFunctor repr where
-- ** Type 'Iso'
data Iso a b = Iso { a2b :: a->b, b2a :: b->a }
+instance Cat.Category Iso where
+ id = Iso Cat.id Cat.id
+ f . g = Iso (a2b f Cat.. a2b g) (b2a g Cat.. b2a f)
-- * Class 'ProductFunctor'
-- | Beware that this is an @infixr@,
--
2.47.2