Naive mergesort implementation in Haskell

mergesort.hs

import Data.List.Utils (merge)
import Data.List.Split (chunksOf)
import Control.Monad (join)
import Control.Arrow -- (***)
import Data.List (sort)


dat = [4,3,2,4,5,6,3,22,4,6,2,1,10,1234,12351,2134,51] :: [Int]

makePair :: [[t]] -> ([t], [t])
makePair (x:y:[]) = (x, y)

msort :: Ord t => [t] -> [t]
msort [single] = [single]
msort multiple = uncurry merge $ join (***) msort $ makePair $ chunksOf (ceiling $ fromIntegral (length multiple) / 2) multiple

main = do
    print $ msort dat
    print $ sort dat