Project Euler, Problem #6, Haskell

-- Find the difference between the sum of the squares of the first one
-- hundred natural numbers and the square of the sum.

-- Solution #1

main :: IO ()
main = print $ sum [1 .. 100] ^ 2 - sum [x ^ 2 | x <- [1 .. 100]]

-- 25164150

-- real 0m0,003s
-- user 0m0,000s
-- sys  0m0,003s

-- Solution #2

main :: IO ()
main = print $ foldl (+) 0 [1 .. 100] ^ 2 - foldl (+) 0 (map (^ 2) [1 .. 100])

-- 25164150

-- real 0m0,007s
-- user 0m0,003s
-- sys  0m0,001s

-- Solution #3

check :: (Num a, Ord a) => a -> a -> a -> a
check d s t =
  if d > 0
    then pow (d - 1) d t
    else t

pow :: (Num a, Ord a) => a -> a -> a -> a
pow d s = accum d (s ^ 2)

accum :: (Num a, Ord a) => a -> a -> a -> a
accum d s t = check d s (t + s)

sumRange :: (Ord t, Num t) => t -> t -> t
sumRange d t =
  if d > 0
    then sumRange (d - 1) (t + d)
    else t

main :: IO ()
main = print $ sumRange 100 0 ^ 2 - check 100 0 0

-- 25164150

-- real 0m0,007s
-- user 0m0,003s
-- sys  0m0,001s