Discussion on: Understanding Recursion with Elixir

[Costin Giorgian]

Hi @sophiedebenedetto,

I propose you a smaller solution:

defmodule MyList do
  def delete_all([head | tail], el) when head === el do
    delete_all(tail, el)
  end

  def delete_all([head | tail], el) do
    [head | delete_all(tail, el)]
  end

  def delete_all([], _) do
    []
  end  
end

I think is better because we get rid of additional parameter new_list and no need to reverse final result.
My first time coding in Elixir. Looks very nice at first glance.
Reminds me of the time when I played with Ruby and Haskell.

Thank you for the post

[Sophie DeBenedetto]

Awesome! I love this solution, definitely more simple. Thanks for sharing!

[Josh Cheek]

Is Elixir able to do this efficiently? In particular, I'm wondering about the callstack, does it keep the frame on the stack while it figures out the RHS of the list, or is it smart enough to build the list element (presumably called cons, at least that's what they'd call it in lisp), and then fill in the RHS values as they become available?

I seriously didn't know that Elixir had tail call optimization, that is super fkn cool! lol, but now I'm all curious how it works. If you gave these 2 solutions a really long list, I assume the last entry from the blog would be fine, but what about the code in this comment? If it can handle this code without stack overflowing, that would be extremely cool (if it works, then I'm guessing lists would have to have a special case somewhere in the compiler or interpreter).