Check if a list contains a fibonacci sequence in Io.

fibonacciList.io

fibonacci := method(num,
  if (num < 0, return "oops...negative number")
  if (num == 0, return 0)
  if (num == 1, return 1)
  if (num == 2, return 1)
  return fibonacci(num - 1) + fibonacci(num - 2)
)

isFibonacci := method(num,
  if (num < 0, return false)
  for (i, 0, 20,
    fib := fibonacci(i)
    if (num == fib, return true)
    if (num < fib, return false)
  )
)

List isFib := method(
  if (self sort != self, return false)
  foreach(i,
    if (isFibonacci(i),continue,return false)
  )
  return true
)

a := list(9, 2, 3)
if (a isFib, (a .. " is a part of a fibonacci sequence.") println, (a .. " is NOT part of a fibonacci sequence.") println)

b := list(1, 2, 3)
if (b isFib, (b .. " is a part of a fibonacci sequence.") println, (b .. " is NOT part of a fibonacci sequence.") println)

c := list(5, 8, 13)
if (c isFib, (c .. " is a part of a fibonacci sequence.") println, (c .. " is NOT part of a fibonacci sequence.") println)

d := list(5, 98, 13)
if (d isFib, (d .. " is a part of a fibonacci sequence.") println, (d .. " is NOT part of a fibonacci sequence.") println)

e := list(5, 8, 13, 14)
if (e isFib, (e .. " is a part of a fibonacci sequence.") println, (e .. " is NOT part of a fibonacci sequence.") println)

f := list(5, 8, 13, 2)
if (f isFib, (f .. " is a part of a fibonacci sequence.") println, (f .. " is NOT part of a fibonacci sequence.") println)

g := list("blah", 8, 13)
if (g isFib, (g .. " is a part of a fibonacci sequence.") println, (g .. " is NOT part of a fibonacci sequence.") println)