From 6dee5caf29c2b17f70862f3bc0e6e6415d38ed20 Mon Sep 17 00:00:00 2001
From: Xiretza <xiretza@xiretza.xyz>
Date: Wed, 16 Dec 2020 17:49:01 +0100
Subject: [PATCH] day16/haskell: prettify findSingletonChoice

---
 2020/day16/day16.hs | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/2020/day16/day16.hs b/2020/day16/day16.hs
index 9ecf561..b5ccf44 100644
--- a/2020/day16/day16.hs
+++ b/2020/day16/day16.hs
@@ -66,11 +66,12 @@ resolve = sequence . map fromResolved . iterateUntilNothing resolve' . map (Choi
           fromResolved _ = Nothing
 
 findSingletonChoice :: [Resolve a] -> Maybe (a, [Resolve a])
-findSingletonChoice (c@(Choice s):xs) | S.size s == 1 = let [x] = S.elems s
-                                                        in Just (x, Resolved x:xs)
-                                      | otherwise = (fmap.fmap) (c:) $ findSingletonChoice xs
-findSingletonChoice (x:xs) = (fmap.fmap) (x:) $ findSingletonChoice xs
-findSingletonChoice _ = Nothing
+findSingletonChoice [] = Nothing
+findSingletonChoice (x:xs) =
+    case x of
+      Choice s | S.size s == 1 -> let [r] = S.elems s
+                                  in  Just (r, Resolved r : xs)
+      _ -> fmap (\(r, rest) -> (r, x:rest)) $ findSingletonChoice xs
 
 resolve' :: Ord a => [Resolve a] -> Maybe [Resolve a]
 resolve' xs = do