Gleam v Elixir interop with BEAM

Joe Armstrong had no issues using elixir code from erlang, fwiw.

You can call elixir functions from erlang or gleam just fine. Where the issues are is elixir macro’s, which don’t work with anything else except elixir (since it happens at compile-time in the elixir compiler).

I love that he basically wrote a guide on how to do it and then asked if there were such a guide at the end.

Does that include built-in macros like if/2?

Note: An interesting note regarding if/2 and unless/2 is that they are implemented as macros in the language; they aren’t special language constructs as they would be in many languages.

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I am not sure I follow. To call elixir functions from outside, one would still need a beam file, to produce it one needs elixir compiler, which would in turn expand macros.

That said, I don’t see any special issue with macros.

def is a macro, defmodule is a macro, defmacro is a macro, after all. Macros are expanded into AST, there won’t be any issues with them, AFAICT.

Try building an ecto query within an erlang module. That won’t work.

Yes, that’s a macro, not a function.

Yes, and after expansion the macro’s no longer exist, only functions remain, hence why you can call elixir functions from other languages, but you cannot call elixir macro’s from other languages.

The ‘big’ elixir libraries use macro’s heavily, hence why they aren’t really useful outside of elixir.

The issue is that it’s the elixir compiler that expands the macro’s, not other languages, hence why another language can’t call an elixir macro (usefully anyway).

Ah, got it, thanks for the clarification! I would not expect people to directly call macros from outside.

Got it. I simply missed the possibility that one would expect calling macros from outside to work.