sumer :: Integer -> Integer

sumer 0 = 0

sumer n = n + sumer (n-1)

collatz :: Integer -> [Integer]

collatz n

| n==1 = [1]

| mod n 2 ==0 = n : collatz (div n 2)

| otherwise = n : collatz (3*n+1)

foo :: Integer -> Integer

foo 0 = 16

foo 1

| "Haskell" > "C++" = 3

| otherwise = 4

foo n

| n<0 = 0

| mod n 17 == 2 = -43

| otherwise = n+3

a :: Char

a = '帥'

p :: (Int, Char)

p = (3, '夏')

f :: (Int, Int) -> Int

f (x, y) = x + y

g :: Int -> Int -> Int -> Int

g x y z = x + y + z

{- function application has 

higher precedence than any 

infix operators

-}

str1 :: [Char]

str1 = ['L', 'O', 'V', 'E']

str2 :: String

str2 = "LOVE"

emptyList = []

list1 = 1:[]

list2 = 2 : (1 :[])

list3 = 3 : 2 : 1 : []

nums, range1, range2 :: [Int]

nums = [1,2,4,6]

range1 = [2..10] -- 2,3,4,5,6,7,8,9,10

range2 = [3,6..18] -- 3,6,9,12,15,18

range3 = [3,6..19] -- 3,6,9,12,15,18 

main = print (collatz 3)