-- sq x returns the square of x
sq :: Integer -> Integer
sq x = x * x

-- absolute x returns the absolute value of x
absolute :: Integer -> Integer
absolute x | x >= 0 = x
absolute x | x < 0  = -x

-- (alternative solution)
absolute' :: Integer -> Integer
absolute' x | x >= 0 = x
	           | x < 0  = -x

-- power x n returns x to the power n
power :: Integer -> Integer -> Integer
power x 0         = 1
power x n | n > 0 = x * power x (n-1)

-- repli n s returns n copies of s as a string
repli :: Integer -> String -> String
repli 0 s         = ""
repli n s | n > 0 = s ++ repli (n-1) s

-- regions n computes the number of regions formed by n lines
regions :: Integer -> Integer
regions 0         = 1
regions n | n > 0 = regions (n-1) + n

-- group n xs divides xs up into groups of length n
group :: Int -> String -> [String]
group n "" = []
group n s  = [take n s] ++ group n (drop n s)