Cannot compile gleam_stdlib when using mix_gleam

[mradke]

I’m currently trying to test gleam inside of a mix project. I followed the GitHub - gleam-lang/mix_gleam: ⚗️ Build Gleam code with mix readme but when I try to compile I’ll get the following error:

Could not compile :gleam_stdlib, no "mix.exs", "rebar.config" or "Makefile" (pass :compile as an option to customize compilation, set it to "false" to do nothing)

The configuration in mix.exs looks like this:

...
  @app :gleam_exp

  def project do
    [
      app: @app,
      version: "0.1.0",
      elixir: "~> 1.14",
      elixirc_paths: elixirc_paths(Mix.env()),
      start_permanent: Mix.env() == :prod,
      aliases: aliases(),

      # Gleam config
      archives: [mix_gleam: "~> 0.6"],
      compilers: [:gleam | Mix.compilers()],
      aliases: [
        # Or add this to your aliases function
        "deps.get": ["deps.get", "gleam.deps.get"]
      ],
      erlc_paths: [
        "build/dev/erlang/#{@app}/_gleam_artefacts",
        # For Gleam < v0.25.0
        "build/dev/erlang/#{@app}/build"
      ],
      erlc_include_path: "build/dev/erlang/#{@app}/include",
      # For Elixir >= v1.15.0
      prune_code_paths: false,

      deps: deps(),
    ]
  end
...

Elixir version: 1.16.3 (compiled with Erlang/OTP 25)
Gleam version: 1.3.2

Any pointers why this is happening?

[dvic]

And you added gleam_stdlib to the mix deps?

# in mix.exs
# ...
  defp deps do
    [
      # ...
      {:gleam_stdlib, "~> 0.34 or ~> 1.0"},
      {:gleeunit, "~> 1.0", only: [:dev, :test], runtime: false},
      # ...
    ]
  end
# ...

[mradke]

Thanks for the answer! Yes. I followed the guide and added the deps. They are also in the deps folder locally but they are indeed missing the "mix.exs", "rebar.config" or "Makefile" files.

[dvic]

And what about the example project? https://github.com/gleam-lang/mix_gleam/tree/main/test_projects/basic_project

I just checked that one and mix test runs fine on my machine (OTP 27 + Elxir 1.17) (after running mix deps.get).

[zakw]

Hello, I believe I have a reproduction of the issue that @mradke ran into.

For me, it was in the context of attempting to add Gleam to an existing Phoenix application. The default Phoenix template has a slightly more involved mix.exs than a default mix new project so perhaps that's what was masking the discovery of this issue.

Here is a simplified repo with each commit representing the set of steps to reproduce and subsequently "fix" the issue with a hack:
https://github.com/zakw/gleam_mix_test/commits/main/

Steps to Reproduce

1. Ensure Phoenix is installed mix archive.install hex phx_new (see https://hexdocs.pm/phoenix/installation.html)
2. Create a new default Phoenix project mix phx.new gleam_test --database sqlite3
3. Add Gleam compiler and dependencies support following the standard README.md
4. Run mix setup

Note: In-between test attempts I would run git clean -xdf to ensure I had a clean, first-time environment before running mix setup again.

Observations

• The first time mix setup is invoked, the gleam_stdlib fails to compile. It appears to compile after a subsequent invocation of mix setup and continue with the application first-time setup.
• If you instead invoke mix deps.get and then run mix setup, separately, it builds and runs without issue even though setup invokes deps.get, itself
• No amount of tweaking or adding compile, deps.compile, deps.compile gleam_stdlib to the various aliases seemed to avoid the first-time compilation issue

The "Fix"

My hack fix was to modify the gleam.deps.get command to cmd mix gleam.deps.get to run it in a separate process. My sneaking suspicion is that either:

• a) there is some post-invocation magic that gleam.deps.get does which is not properly captured by the setup alias pipeline or
• b) there is some environment issue induced by gleam.deps.get that is avoided by running it in a separate process

This "hack fix" is illustrated, here:
zakw/gleam_mix_test@1be6c9c

I'm unsure what the true underlying issue is or what the appropriate solution is, but I thought I'd illustrate my findings here in case that helps point someone who knows more about this system in a good direction.

System Environment

• Windows 10 22H2 x64
• Powershell 7.5.4
• VS Code 1.107.1
• Erlang/OTP 28
• Elixir 1.19.4
• Phoenix 1.8.3
• Gleam 1.14.0

(Copied to gleam-lang/mix_gleam#44)