Even wilder performance increases

src/projectEuler/question14.hs

@@ -16,24 +16,24 @@ NOTE: Once the chain starts the terms are allowed to go above one million.
 -}
 module Main where
 
-import           Data.List (genericLength, sortOn)
+import           Data.List (sortOn)
 import           Data.Ord  (Down (Down))
 
 main :: IO ()
 main = print ans
 
-ans :: Integer
+ans :: Int
 ans = fst $ head $ sortOn (Down . snd) $ map collatzChainStartingAt [1..limit]
 
-nextCollatz :: Integer -> Integer
+nextCollatz :: Int -> Int
 nextCollatz n
   | n == 1 = 0
   | even n = n `div` 2
   | odd  n = 3*n + 1
 
-collatzChainStartingAt :: Integer -> (Integer, Integer)
+collatzChainStartingAt :: Int -> (Int, Int)
 collatzChainStartingAt n = (n, s')
-  where s' = genericLength $ takeWhile (/= 0) $ iterate nextCollatz n
+  where s' = length $ takeWhile (/= 0) $ iterate nextCollatz n
 
-limit :: Integer
+limit :: Int
 limit = 1_000_000