Generating Fibonacci series in F#

Question

I\'m just starting to learn F# using VS2010 and below is my first attempt at generating the Fibonacci series. What I\'m trying to do is to build a list of all numbers less

Answer 1

Here's an infinite tail-recursive solution using sequence expressions. It's quite efficient, producing the 100,000th term in just a few seconds. The "yield" operator is just like C#'s "yield return", and the "yield!" operator may be read as "yield all", where in C# you would have to do "foreach item ... yield return item".

https://stackoverflow.com/questions/2296664/code-chess-fibonacci-sequence/2892670#2892670

let fibseq =    
    let rec fibseq n1 n2 = 
        seq { let n0 = n1 + n2 
              yield n0
              yield! fibseq n0 n1 }
    seq { yield 1I ; yield 1I ; yield! (fibseq 1I 1I) }

let fibTake n = fibseq |> Seq.take n //the first n Fibonacci numbers
let fib n = fibseq |> Seq.nth (n-1) //the nth Fibonacci number

This approach is similar to the following in C# (which uses a while(true) loop instead of recursion):

Finding Fibonacci sequence in C#. [Project Euler Exercise]