Haskell: Calculates number of cans in a pyramid or sum of all cans in pyramids

cans.hs

-- cans.hs

-- Calculate number of cans in one pyramid
cansInPyramid :: Int -> Int
cansInPyramid 1 = 1
cansInPyramid n = n + cansInPyramid (n - 1)

-- Smaller solution
cansInPyramid' n = sum [1..n]

-- Calculates number of cans in all pyramids
sumOfPyramids :: Int -> Int
sumOfPyramids 1 = 1
sumOfPyramids n = cansInPyramid n + sumOfPyramids (n - 1)

-- Smaller solution
sumOfPyramids' n = sum $ map cansInPyramid' [1..n]

main = do
        print $ cansInPyramid 8 -- 36
        print $ sumOfPyramids 8 -- 120
        print $ cansInPyramid' 8 -- 36
        print $ sumOfPyramids' 8 -- 120