cinderella-man / hands-on-elixir-and-otp-cryptocurrency-trading-bot Goto Github PK

Hi, I noticed 2 mismatch with map returned by fetch_symbol_settings/1:

1. The key :symbol added in chapter 5 now is disappeared

2. In chapter intro we can read

   should never be smaller than double the fee(at the moment of writting transaction fee is 0.1%) that you are paying per transaction

   The value assigned is 0.0001 but I expect 2 times 0.1% and so 0.002. I probably misunderstood how you assigned this value. Can you clarify me this point?

Thank you!

Reading through your book. Really enjoying it so far. I came across this piece of code at the end of 2.3.2

defp calculate_sell_price(buy_price, profit_interval, tick_size) do
    fee = D.new("1.001")
    original_price = D.mult(D.new(buy_price), fee)

    net_target_price =
      D.mult(
        original_price,
        D.add("1.0", profit_interval)
      )

    gross_target_price = D.mult(net_target_price, fee)

    D.to_float(
      D.mult(
        D.div_int(gross_target_price, tick_size),
        tick_size
      )
    )
  end

However the commentary that is provided immediate after is a little confusing. For instance there is this quote,

We started by calculating the gross_buy_price which is a sum of buy price together with the fee that we paid on top of it.

I do not see gross_buy_price, but perhaps that was intended to be original_price, however the original_price variable is not calculate with a sum like the above quote states it is D.mult(D.new(buy_price), fee). There is another quote that is similar,

As we will be charged a fee for selling, we need to add the fee again on top of this target sell price(gross_target_price).

Again, that is referring to the line gross_target_price = D.mult(net_target_price, fee) which is also a multiplication and not a sum.

In chapter 5, where we see an diagram representing the supervision tree, it seems like there is an error in https://github.com/Cinderella-Man/hands-on-elixir-and-otp-cryptocurrency-trading-bot/tree/main/images/chapter_05_03_full.png,https://github.com/Cinderella-Man/hands-on-elixir-and-otp-cryptocurrency-trading-bot/tree/main/images/chapter_05_04_full.png and https://github.com/Cinderella-Man/hands-on-elixir-and-otp-cryptocurrency-trading-bot/tree/main/images/chapter_05_05_full.png,
where the bottom most Naive.Leader should actually read Naive.Trader. Otherwise, I might be understanding this wrong.

Related images:

Seems like you need to specify "us" if you're in the US of A:

wss://stream.binance.us:9443/ws/

If you can point that out in the docs, I'll submit a PR.

Hello! I love your book 💟 !!! awesome work!

I believe that alias Decimal in chapter 10. serve no purpose

I've been following along the book as a practice method until I found myself blocked with the following issue:
Environment:
Elixir 1.11.4 Erlang/OTP 23

Relevant code snippet

# apps/streamer/lib/streamer/application.ex
def start(_type, _args) do
    children = [
      {
        Phoenix.PubSub,
        name: Streamer.PubSub, adapter_name: Phoenix.PubSub.PG2
      }
    ]

    opts = [strategy: :one_for_one, name: Streamer.Supervisor]
    Supervisor.start_link(children, opts)
  end

Expected:
iex -S mix starts the application correctly.

Actual result:
iex -S mix produces error:
** (Mix) Could not start application streamer: Streamer.Application.start(:normal, []) returned an error: shutdown: failed to start child: Phoenix.PubSub.Supervisor ** (EXIT) shutdown: failed to start child: Phoenix.PubSub.PG2 ** (EXIT) exited in: :gen_server.call(Phoenix.PubSub, {:join_local, Streamer.PubSub.Adapter, #PID<0.251.0>}, :infinity) ** (EXIT) no process: the process is not alive or there's no process currently associated with the given name, possibly because its application isn't started

Besides changing the Elixir/OTP versions, I see no way of debugging this. Any idea?

Hello @Cinderella-Man! still enjoying the book 💟

maybe did you mean data?

its me with more typos 🙈

it should be autostart_trading