Question

with the multiple assignment (ie a,b=b,a) in f# its possible to write Fibonacci in a single line .. Can some one show how it is .. i know its possible in ruby

Answer 1

Scott Hanselman pretty much covers this in this blog post.

Here is the relevant snippet:

let rec fib n = if n < 2 then 1 else fib (n-2) + fib(n-1)

Scott got that from Dustin Cambell’s blog. I post Scott’s version because he also has the Ruby code for it. It’s worth noting that in F#, variables are generally immutable so a,b = b,a is not actually reassigning anything (I don’t think it’s even valid syntax). Rather, a function like let swap (a,b) = (b,a) is taking a tuple and returning a new tuple with the contents reversed.