Fibonacci (again)

fib

#!/usr/bin/env elixir

defmodule Math do
  def fibfast(n) do fib_acc(1, 0, n) end
  def fib_acc(a, b, 0) do a + b end
  def fib_acc(a, b, n) do fib_acc(b, a+b, n-1) end

  def fibslow(0) do 1 end
  def fibslow(1) do 1 end
  def fibslow(n) do fibslow(n-1) + fibslow(n-2) end
end

extract_args = fn() ->
  System.argv() |> Enum.map(fn(n) ->
    n |> Integer.parse() |> elem(0)
  end)
end

print_fib = fn(n) ->
  n |> Math.fibfast() |> IO.puts()
end

case extract_args.() do
  [n] -> print_fib.(n)
  [a, b] -> a..b |> Enum.each(print_fib)
  _ -> IO.puts("argument error")
end