Fibonacci Code Golf

Question

Generate the Fibonacci sequence in the fewest amount of characters possible. Any language is OK, except for one that you define with one operator, f, which prints the Fibonacci numbers.

Starting point: 25 14 characters in Haskell:

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

f=0:scanl(+)1f

Answer 1

Ruby (30 characters):

def f(n)n<2?n:f(n-1)+f(n-2)end

Answer 2

Microsoft Batch - 15 characters

Old challenge, but the world must know it is possible:

%1
%0 %1%2 %1 #

Output is to stderr in unary, counting only the # characters. Depending on the host system's space restrictions, it may produce only the first 14 numbers or so.

Answer 3

F#:

(0,1)|>Seq.unfold(fun(a,b)->Some(a,(b,a+b)))

44 Chars

Answer 4

C#

I'm seeing a lot of answers that don't actually generate the sequence, but instead give you only the fibonacci number at position *n using recursion, which when looped to generate the sequence gets increasingly slower at higher values of n.

using System;
static void Main()
{
  var x = Math.Sqrt(5);
  for (int n = 0; n < 10; n++)
    Console.WriteLine((Math.Pow((1 + x) / 2, n) - Math.Pow((1 - x) / 2, n)) / p) ;
}

Answer 5

33 characters in C:

F(n){return n<2?n:F(n-1)+F(n-2);}

Answer 6

Perl 6 - 22 characters:

sub f{1,1...{$^a+$^b}}