Raising a number to the power of another number. exponent. in haskell

power :: Float -> Float -> Float

power m n

| n == 0        = 1

| n > 0         = m* power m (n-1)

| otherwise     = (1 / m)* power m (n+1)

finding the highest common factor/divisor for two integers in haskell

hcf :: Int -> Int -> Int

--handles all cases of zero

hcf 0 0 = undefined 

hcf m 0 = abs m

hcf 0 n = abs n

hcf m n 

    | m == n       = m 

    | m > n        = hcf n (rem m n) 

    | otherwise    = hcf n m

Integer square root of a positive integer in haskell

squareRoot :: Int -> Int

squareRoot n 

| n ==  1              = 1 

| otherwise            = div (k + ( div n k)) 2

where k = squareRoot(n-1) 

Using recursive addition to multiply in haskell

multiply :: Int -> Int -> Int

multiply m n

| n >= 1        = m + multiply (n-1) m

| otherwise     = 0

Finding the average of three numbers in haskell

averageThree :: Float -> Float -> Float -> Float

averageThree  a b c = (a + (b + c))/3.0

isAbove :: Float -> Float -> Int

isAbove a avg

 | a > avg = 1

 | otherwise = 0

numAbove :: Float -> Float -> Float -> Int

numAbove a b c = (isAbove a avg) + (isAbove b avg) + (isAbove c avg)

  where

   avg = averageThree a b c