Setting the upper limit to the input set in accordance with the output function

Question

I am currently stuck in setting upper limits on lists.

What I'm trying to do is find all the Fibonacci numbers below a million. To do this, I developed a fairly simple recursive Fibonacci function

fib :: Int -> Integer
fib n
    n == 0    = 0
    n == 1    = 1
    otherwise = fib (n-1) + fib (n-2)

What I'm stuck with is the definition of a million parts. Now I have:

[ fib x | x <- [0..35], fib x < 1000000 ]

This is because I know that the 35th number in the Fibonacci sequence is a fairly high number. However, what I would like is to find this limit through a function and set it this way.

[ fib x | x <- [0..], fib x < 1000000 ]

It gives me numbers, but it just doesn't stop. This leads to the fact that Haskell is trying to find Fibonacci numbers below a million in the sequence, which is pretty useless.

Can anyone help me with this? It would be very grateful!

Answer 1

fib x < 1000000 fib x, 1000000; , x fib x , , , x.

takeWhile:

takeWhile (< 1000000) [ fib x | x <- [0..35]]

Answer 2

. takeWhile :: (a -> Bool) -> [a] -> [a]. takeWhile (< 1000000) $ map fib [1..]. takeWhile , ; dropWhile, , , span :: (a -> Bool) -> [a] -> ([a], [a]), (takeWhile p xs, dropWhile p xs) break, , ( span (not . p). , :

• takeWhile (< 3) [1,2,3,4,5,4,3,2,1] == [1,2]
• dropWhile (< 3) [1,2,3,4,5,4,3,2,1] == [3,4,5,4,3,2,1]
• span (< 3) [1,2,3,4,5,4,3,2,1] == ([1,2],[3,4,5,4,3,2,1])
• break (> 3) [1,2,3,4,5,4,3,2,1] == ([1,2,3],[4,5,4,3,2,1])

Answer 3

, "" ( ) ,

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

takeWhile (<100) fibs
--[0,1,1,2,3,5,8,13,21,34,55,89]

( "" ), " ", .

A "loopy" ( "" ) :

fibs = map fst $ iterate (\(a,b) -> (b,a+b)) (0,1) 

[]

( ) :

fib n = second $ (0,1,1,1) ** n where
   p ** 0 = (1,0,0,1)
   p ** 1 = p
   p ** n | even n = (p `x` p) ** (n `div` 2)
          | otherwise = p `x` (p ** (n-1))
   (a,b,c,d) `x` (q,r,s,t) = (a*q+b*s, a*r+b*t,c*q+d*s,c*r+d*t)
   second (_,f,_,_) = f

( , )

Answer 4

, :

[ fib x | x <- [1..1000000] ] 

fib n > n n > 3.