2021

1 files changed, 14 insertions, 0 deletions

diff --git a/2021/Util.hs b/2021/Util.hs
new file mode 100644
index 0000000..7cd674d
--- /dev/null
+++ b/2021/Util.hs
@@ -0,0 +1,14 @@
+module Util where
+
+import Data.List
+import Data.List.NonEmpty (NonEmpty(..), (<|))
+
+
+splitOn :: (a -> Bool) -> [a] -> NonEmpty [a]
+splitOn _ [] = [] :| []
+splitOn f (x:xs) | f x = [] <| splitOn f xs
+                 | otherwise = let l :| ls = splitOn f xs
+                               in (x : l) :| ls
+
+splits' :: [a] -> [(a, [a])]
+splits' l = zip l (zipWith (++) (inits l) (tail (tails l)))