Alternate approach

[Will-W]

You are probably aware of this, but there is another approach that you don't address in your README. In this approach, the library provides a 'using' macro that the consumer of the API can use to create a single purpose module with the appropriate parameters.

The mailer 'Swoosh' is a good example of doing this. This is the entire contents of one module in my system:

defmodule DoorstepWeb.Mailer do
  use Swoosh.Mailer, otp_app: :doorstep
end

Then, rather than calling Swoosh directly, I call DoorstepWeb.Mailer and the use directive has created all the API functions I need, with the appropriate adjustments (presumably passing through to equivalent internal functions, adding otp_app as an extra arg).

In this case you would only ever need one implementation, but if it was being used to inject some other form of dependency (like a mailing provider), you might instantiate several and then use the appropriate module in your code.

There is a downside of greppability, and of having a per-library macro burden to make it work. It's quite natural to the consumer though.

[by the way - I hope it's ok to put this here]

[QuinnWilton]

This is a really great suggestion, thank you! It is absolutely okay to put this here :)