-- comment
-- :set +t   -- types everything

fibs = 0:1:zipWith (+) fibs (tail fibs)

fact n = product [1..n]

comb n r = fact n `div` (fact r * fact (n-r))

data Time = MakeTime { hours, mins, secs :: Int }

-- Page 595 Sebesta

sumAll :: [Integer] -> Integer
sumAll [] = 0
sumAll (a:x) = a + sumAll x

productAll :: [Integer] -> Integer
productAll [] = 1
productAll (a:x) = a * productAll x

colors = [ "blue", "green", "red", "yellow" ]

factors :: Integer -> [Integer]
factors n = [ i | i <- [1..n `div` 2], n `mod` i == 0]

sort :: [Integer] -> [Integer]
sort [] = []
sort (a:x) = sort [b | b <- x, b <= a] ++ [a] ++ sort [ b | b <- x, b > a]

positives = [ 1 .. ]
evens = [ 2 , 4 .. ]
squares = [n*n | n <- [0..]]

--ordered list of integers
member :: [Integer] -> Integer -> Bool
member [] n = False
member (m:x) n = ((m < n) && (member x n)) || (m == n) || False

-- translate problem 11 on p. 603

y s [] = []
y s (t:x) | (s==t) = (s:x)
          | otherwise = y s x

--Greatest Common Divisor

mygcd m n | (n > m) = mygcd n m    -- so m>=n
          | ((m `mod` n) == 0) = n
          | otherwise = mygcd n (m `mod` n)

cubes = [ n*n*n | n <- [1..] ]