0_fib.rb

def fib(n)
  if n <= 1
    return n
  else
    return fib(n-1) + fib(n-2)
  end
end

puts fib(30)

1_sexp.rb

s(:block,
 s(:defn,
  :fib,
  s(:scope,
   s(:block,
    s(:args, :n),
    s(:if,
     s(:call, s(:lvar, :n), :<=, s(:array, s(:lit, 1))),
     s(:return, s(:lvar, :n)),
     s(:return,
      s(:call,
       s(:fcall,
        :fib,
        s(:array, s(:call, s(:lvar, :n), :-, s(:array, s(:lit, 1))))),
       :+,
       s(:array,
        s(:fcall,
         :fib,
         s(:array, s(:call, s(:lvar, :n), :-, s(:array, s(:lit, 2)))))))))))),
 s(:fcall, :puts, s(:array, s(:fcall, :fib, s(:array, s(:lit, 30))))))

2_fib.neko

fib = function(n) {
  if (n <= 1) {
    return n
  }
  else {
    return (fib((n - 1)) + fib((n - 2)))
  }
}
$print(fib(30))