From 9401a752312a0947dcc56184fadb23d7545329c1 Mon Sep 17 00:00:00 2001
From: Mike Solomon <mike@meeshkan.com>
Date: Sat, 11 Sep 2021 21:20:57 +0300
Subject: [PATCH 1/2] Adds recastCofree

---
 src/Control/Comonad/Cofree.purs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/Control/Comonad/Cofree.purs b/src/Control/Comonad/Cofree.purs
index 91bb6e8..046f1b7 100644
--- a/src/Control/Comonad/Cofree.purs
+++ b/src/Control/Comonad/Cofree.purs
@@ -60,6 +60,16 @@ tail (Cofree c) = snd (force c)
 hoistCofree :: forall f g. Functor f => (f ~> g) -> Cofree f ~> Cofree g
 hoistCofree nat (Cofree c) = Cofree (map (nat <<< map (hoistCofree nat)) <$> c)
 
+-- | Recasts a cofree comonad's functor from `f` to `g` by
+-- | passing a function in which `g` can annihilate `f`.
+recastCofree
+  :: forall f g a
+   . Functor f
+  => (forall z. (Cofree f a -> z) -> f (Cofree f a) -> g z)
+  -> Cofree f a
+  -> Cofree g a
+recastCofree w (Cofree c) = Cofree ((map <<< map) (w (recastCofree w)) c)
+
 -- | This signature is deprecated and will be replaced by `buildCofree` in a
 -- | future release.
 unfoldCofree

From 178b16dcea6b1e6ff607caa6eb5d6171ffd4c507 Mon Sep 17 00:00:00 2001
From: Mike Solomon <mike@meeshkan.com>
Date: Sun, 12 Sep 2021 07:05:36 +0300
Subject: [PATCH 2/2] Rewrites hoistCofree using recastCofree

---
 src/Control/Comonad/Cofree.purs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Control/Comonad/Cofree.purs b/src/Control/Comonad/Cofree.purs
index 046f1b7..209c9a0 100644
--- a/src/Control/Comonad/Cofree.purs
+++ b/src/Control/Comonad/Cofree.purs
@@ -58,7 +58,7 @@ tail :: forall f a. Cofree f a -> f (Cofree f a)
 tail (Cofree c) = snd (force c)
 
 hoistCofree :: forall f g. Functor f => (f ~> g) -> Cofree f ~> Cofree g
-hoistCofree nat (Cofree c) = Cofree (map (nat <<< map (hoistCofree nat)) <$> c)
+hoistCofree nat = recastCofree (compose nat <<< map)
 
 -- | Recasts a cofree comonad's functor from `f` to `g` by
 -- | passing a function in which `g` can annihilate `f`.