From 604206776fa469a3ccc55311126ca8864380c2fe Mon Sep 17 00:00:00 2001
From: pingu <nor@acorneroftheweb.com>
Date: Thu, 29 Feb 2024 19:02:20 +0100
Subject: [PATCH] Monad, probs

---
 src/GoodList.hs | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/GoodList.hs b/src/GoodList.hs
index c24ac19..47f66c6 100644
--- a/src/GoodList.hs
+++ b/src/GoodList.hs
@@ -22,9 +22,7 @@ instance Applicative GoodList where
 -- Needs to be proven
 instance Monad GoodList where
   return = pure
-  Empty          >>= _ = Empty
-  Singleton x    >>= f = f x
-  Multiple a b c >>= f = append (append (f a) (b >>= f)) (f c)
+  x >>= f = join $ fmap f x
 
 instance Semigroup (GoodList a) where
   (<>) = append
@@ -60,3 +58,8 @@ append (Singleton x)     ys              = cons x ys
 append  xs               Empty           = xs
 append (Multiple a b c) (Singleton y)    = Multiple a (snoc b c) y
 append (Multiple a b c) (Multiple d e f) = Multiple a (snoc b c `append` cons d e) f
+
+join :: GoodList (GoodList a) -> GoodList a
+join Empty = Empty
+join (Singleton x) = x
+join (Multiple a b c) = append (a `append` join b) c