Some thinking from Elixir X Ruby Conf

Although title contains Ruby, but I won't talk too much on it, because I did not learn it. This conf is my first conf. I learn something at here, and I will write down in following text.

The first impress talk is using Elixir & Kafka write a server can handle 200 millions user communication on it. Speaker is a Japanese, I can't understand his English a lot. However, his paper show how does he compare different machine & different tech stack, so that's fine. Second is about choosing style! Speaker shows some web library/framework in Ruby/Elixir/Erlang and compare the style between them. He says: Style is about choosing. Then a speaker talking how RDoc work, it's useful for me because I am implementing a programming language and hope it can become a language can use in real development.

p.s. RDoc is Ruby doc generator.

Then MJIT is the next thing I am impressed. It's about JIT implementation in Ruby.

Final is Jose(Elixir writer. e is not that one, but I don't know how to type it from my laptop, so sorry for him)'s talk. Of course, he's introducing Elixir for us, not syntax level, but about design issue: Why we need immutable? Why is actor(Erlang concurrency model)? Then he shows a new way testing. Test the concept. We all know test. For example:

defmodule ExampleTest do
  use ExUnit.Case
  doctest Example

  test "one plus one is two" do
    assert 1 + 1 == 2
  end
end

However, can we really test anything? How many tests we need? Take a look

defmodule StringContainsTest do
  use ExUnit.Case

  test "abc contains ab" do
    assert String.contains? "abc", "bc"
  end
end

What about ("erhonbkd", "")? ("", "")? If we test?

defmodule StringContainsTest do
  use ExUnit.Case

  @spec a :: string()
  @spec b :: string()
  test "a <> b should contain a & b" do
    s = a <> b
    assert String.contains? s, a
    assert String.contains? s, b
  end
end

Then just let compiler generating all the edge case you hard to cover. Now let me talk something from Jose's speech, I think more. If we can use the user's input, testing more thing? For example, each time user have using String.contains?. We use all string them used to generate test for String.contains?If it broke. User can find the bug for us!!!