I have seen many Haskell programs that when a user enters 5 it will return the first 5 elements of the Fibonacci sequence, however, I need it to only output the values of the Fibonacci sequence that are less than or equal to 5.
For example: Fib 15 needs to output 1 1 2 3 5 8 13
Fib 7 needs to output 1 1 2 3 5
This is what I have & am trying to alter to output up to the given value and not the given index:
-- individual fib numbers
fib :: Int -> Int
fib 0 = 1
fib 1 = 1
fib n = fib (n - 1) + fib (n - 2)
-- example run fib 6 returns the int at position 6
-- so fib 6 = 13
-- combines individual fib numbers
fibonacciSequence x = map fib[1..x]
Some things I have tried:
fibonacciSequence x = map (\x -> fib[1..] > x ) [1..]
y = filter (\y -> y > x) fib[1..x]
fibonacciSequence x = map (inRange (1,x)) [1..]
fibonaci g = map fst (iterate f (0,1)) where f (x,y) = (y,x+y) | f(y, x+y) <= g
I am very new to Haskell and your help would be very appreciated!
Rather than writing a function that generates a finite sequence like:
fibonacciSequence x = map fib [1..x]
It is often more useful to write it as an infinite sequence:
fibonacciSequence = map fib [1..]
Then you can choose which parts you want freely, for the first n elements you can use:
take n fibonacciSequence
And if you want the Fibonacci numbers up to n you can do it like this:
takeWhile (<= n) fibonacciSequence