gistfile1.ex

defmodule Recursive do
	def naive_fac(0), do: 1
	def naive_fac(n) when n > 0, do: n * naive_fac(n - 1)

	def tail_fac(n), do: _tail_fac(n,1)
	defp _tail_fac(0, acc), do: acc
	defp _tail_fac(n, acc), do: _tail_fac(n - 1, n*acc)

	def naive_len([]), do: 0
	def naive_len([_|t]), do: 1 + naive_len(t)

	def tail_len(arr), do: _tail_len(arr, 0)
	defp _tail_len([], acc), do: acc
	defp _tail_len([_|t], acc), do: _tail_len(t, acc + 1)

	def duplicate(0, _), do: []
	def duplicate(n, term) when n > 0 do
		[term|duplicate(n - 1, term)]
	end

	def tail_duplicate(n, term), do: _tail_duplicate(n, term, [])
	defp _tail_duplicate(0, _, list), do: list
	defp _tail_duplicate(n, term, list) do
		_tail_duplicate(n-1, term, [term|list])
	end

	def reverse([]), do: []
	def reverse([h|t]), do: reverse(t) ++ [h]

	def tail_reverse(l), do: _tail_reverse(l, [])
	defp _tail_reverse([], acc), do: acc
	defp _tail_reverse([h|t], acc), do: _tail_reverse(t, [h|acc])
end