Haskell Memoized Fibonacci

fibo.hs

fibo 0 = 1
fibo 1 = 1
fibo k = memo_fibo (k - 1) + memo_fibo (k - 2)

memo_fibo :: Int -> Int
memo_fibo  = ((map fibo [0..]) !! )
-- memo_fibo k = ((map fibo [0..]) !! k)
-- this doesn't get memoized
-- https://stackoverflow.com/questions/11466284/how-is-this-fibonacci-function-memoized

fib = (map fib' [0..] !!)                 
     where fib' 1 = 1              
           fib' 2 = 1                    
           fib' n = fib (n-2) + fib (n-1)
           
main = do
  print "*" -- here so you can get a sense of how much time it takes
  print $  memo_fibo 30