data Bool = False | True
data Shape = Circle Float Float Float | Rectangle Float Float Float Float

import Data.List
numUniques :: (Eq a) => [a] -> Int
numUniques = length . nub

compareWithHundred :: (Num a, Ord a) => a -> Ordering
compareWithHundred = compare 100
divideByTen :: (Floating a) => a -> a
divideByTen = (/10)

lucky :: (Integral a) => a -> String
lucky 7 = "LUCKY NUMBER SEVEN!"
lucky x = "Sorry, you're out of luck!"
factorial :: (Integral a) => a -> a
factorial 0 = 1
factorial n = n * factorial (n - 1)
addVectors :: (Num a) => (a, a) -> (b, b) -> (a, a)
addVectors (x1, y1) (x2, y2) = (x1 + x2, y1 + y2)

doubleMe x = x + x
doubleUs x y = doubleMe x + doubleMe y