Finch

// defines a "fib" method on numbers that returns the nth value of the
// fibonacci sequence. uses a slow naive recursive process. useful for
// performance testing.
Numbers :: fib {
 if: self = 0 then: { return 0 }
 if: self = 1 then: { return 1 }
 (self - 2) fib + (self - 1) fib
}

// test
from: 0 to: 20 do: {|i|
 write-line: "" + i + " fib = " + i fib
}