Basic Haskell Math and Utility Functions

module Gyak04 where

    import Data.Char(toLower, toUpper, isLower, isUpper)

    circleArea :: Double -> Double
    circleArea r = (r^2)*pi

    sphereVolume :: Double -> Double
    sphereVolume r = 4*(r^3)*pi/3

    cToF :: Double -> Double
    cToF c = c*(9/5)+32

    raiseSalary :: Double -> Double -> Double
    raiseSalary x y = ((x/y)-1)*100

    min1 :: Int -> Int -> Int
    min1 x y   
        | x <= y = x
        | y < x = y

    min2 :: Int -> Int -> Int
    min2 x y   
        |x <= y = x
        |otherwise = y

    min3 :: Int -> Int -> Int
    min3 x y | x <= y = x
    min3 x y = y

    myAbs :: Integer -> Integer
    myAbs x
        | x >= 0 = x
        | x < 0 = -x

    sign :: Integer -> Integer
    sign x 
        | x < 0 = -1
        | x == 0 = 0
        | x > 0 = 1

    swapUpperLower :: Char -> Char
    swapUpperLower x
        |isUpper(x) == True = toLower(x)
        |isUpper(x) == False = toUpper(x)

    fact :: Integer -> Integer
    fact x 
        | x == 0 = 1
        | x > 0 = x * fact(x-1)
        | otherwise = error "fact: negative number"

    sumTo :: Integer -> Integer
    sumTo 0 = 0
    sumTo n = n + sumTo (n-1)

    sumBetween :: Integer -> Integer -> Integer
    sumBetween n m 
        | n > m = sumTo(n) - sumTo(m-1)
        | m > n = sumTo(m) - sumTo(n-1)
        | m == n = m