Meeseeks (and Rustler) doesn't work with escript.build

[Eiji7]

Hey, I just called &Meeseeks.all/2 function with css like:

import Meeseeks.CSS
Meeseeks.all("html code", css("css selector"))

but I got:

{%Protocol.UndefinedError{description: "", protocol: String.Chars,
  value: {:error, :bad_name}},
 [{String.Chars, :impl_for!, 1,
   [file: '/home/ubuntu/bob/tmp/3251921048f5d8e3ff92bd4156013d87/elixir/lib/elixir/lib/string/chars.ex',
    line: 3]},
  {String.Chars, :to_string, 1,
   [file: '/home/ubuntu/bob/tmp/3251921048f5d8e3ff92bd4156013d87/elixir/lib/elixir/lib/string/chars.ex',
    line: 22]},
  {Rustler, :compile_config, 2, [file: 'lib/rustler.ex', line: 74]},
  {MeeseeksHtml5ever.Native, :__init__, 0,
   [file: 'lib/meeseeks_html5ever/native.ex', line: 4]},
  {:code_server, :"-handle_on_load/5-fun-0-", 1,
   [file: 'code_server.erl', line: 1333]}]}

My dependencies:

* rustler 0.10.1 (Hex package) (mix)
  locked at 0.10.1 (rustler) cedcce8b
  ok
* meeseeks_html5ever 0.6.1 (Hex package) (mix)
  locked at 0.6.1 (meeseeks_html5ever) 3d7f3c4b
  ok
* meeseeks 0.7.2 (Hex package) (mix)
  locked at 0.7.2 (meeseeks) 6410eda0
  ok

Erlang: 20.0
Elixir: 1.5.1-otp-20
Rust: stable - rustc 1.19.0 (0ade33941 2017-07-17)
All installed using asdf.
Let me know if you need more info about my input data.
Edit: I got exactly same error when I changed all to one function name.

[mischov]

If you could provide more info about the input that caused that it would be great.

[Eiji7]

I fetched HTML code of this page: http://www.onepiece.wbijam.pl/pierwsza_seria.html
and tried to load links using selector table.lista a

[mischov]

html = """ 
<The Page Source> 
""""
d = Meeseeks.parse(html)
Meeseeks.all(d, css("table.lista a"))

Returns a list of results for me.

Can you try running Meeseeks.parse on the HTML and seeing if it works?

[mischov]

The Rustler line referenced in the error is: https://github.com/hansihe/rustler/blob/master/rustler_mix/lib/rustler.ex#L74

Is there any reason that that line would cause a problem for you?

[Eiji7]

I found a problem. It works in iex, but not when compiled using mix escript.build.

defmodule Sample do
  import Meeseeks.CSS

  def main([main_url]) do
    Meeseeks.parse HTTPoison.get!(main_url).body
    # minified version - works in iex
  end
end

and here is mix.exs:

defmodule Sample.Mixfile do
  use Mix.Project

  def application, do: [extra_applications: [:logger]]

  def project, do: [
    app: :sample,
    deps: [
      {:httpoison, "~> 0.13"},
      {:meeseeks, "~> 0.7.2"}
    ],
    elixir: "~> 1.5",
    escript: [main_module: Sample],
    start_permanent: Mix.env == :prod,
    version: "0.1.0",
  ]
end
# also minified

rest is as same as after calling: mix new sample.

[mischov]

It looks like that problem might result from a combination of escript.build and Rustler.

The escript.build docs notes the following:

Note: escripts do not support projects and dependencies that need to store or read artifacts from the priv directory.

And the line I linked to above from Rustler, the one in the error, reads

priv_dir = otp_app |> :code.priv_dir() |> to_string()

[Eiji7]

@mischov: oh, is there any other way to compile my project to binary file that could work with rustler?

[mischov]

Well, escripts don't work with NIFs (source), so not in a way that involves an escript.

[mischov]

I don't really know what your use case and restrictions are, but your best bet is probably to make an Erlang/OTP release with something like Distillery.

I am going to close this issue, but feel free to continue commenting if you have more questions or if you want to describe your eventual solution.