[Haskell Practice] some common sorting algorithms

sorting.hs

import Data.List

bubbleSort :: (Ord a) => [a] -> [a]
bubbleSort [] = []
bubbleSort (first:[]) = first:[]
bubbleSort (first:remains) =
    if first < smallest
        then first:(bubbleSort bubbledRemains)
        else smallest:(bubbleSort (first:(tail bubbledRemains)))
    where bubbledRemains = bubbleSort remains
          smallest = head bubbledRemains

insertionSort :: (Ord a) => [a] -> [a]
insertionSort [] = []
insertionSort (first:remains) = before ++ [first] ++ after
    where (before, after) = span (< first) $ insertionSort remains

selectionSort :: (Ord a) => [a] -> [a]
selectionSort [] = []
selectionSort list = first:(selectionSort remains)
    where (first, remains) = fetchSmallest list
          fetchSmallest (first:[]) = (first, [])
          fetchSmallest (first:remains) =
            if first < smallest
                then (first, smallest:others)
                else (smallest, first:others)
            where (smallest, others) = fetchSmallest remains

mergeSort :: (Ord a) => [a] -> [a]
mergeSort [] = []
mergeSort (first:[]) = first:[]
mergeSort list = merge (mergeSort front) (mergeSort back)
    where (front, back) = splitAt ((length list) `div` 2) list
          merge list [] = list
          merge [] list = list
          merge list1 list2 =
              if first1 < first2
                  then first1:(merge (tail list1) list2)
                  else first2:(merge list1 (tail list2))
              where first1 = head list1
                    first2 = head list2

quickSort :: (Ord a) => [a] -> [a]
quickSort [] = []
quickSort (first:remains) = (quickSort before) ++ [first] ++ (quickSort after)
    where (before, after) = partition (< first) remains

main = do
    putStr $ show $ bubbleSort [18, 25, 29, -32, 9, 17]
    putStr "\n"
    putStr $ show $ insertionSort [18, 25, 29, -32, 9, 17]
    putStr "\n"
    putStr $ show $ selectionSort [18, 25, 29, -32, 9, 17]
    putStr "\n"
    putStr $ show $ mergeSort [18, 25, 29, -32, 9, 17]
    putStr "\n"
    putStr $ show $ quickSort [18, 25, 29, -32, 9, 17]
    putStr "\n"