Elixir Context Accessor Function: Which Return Type Do You Prefer?

During a recent Elixir Book Club meeting we had a back and forth discussion on a simple code style question:

When providing an accessor function inside your domain context, do you prefer a return type of {:ok, noun} || {:error, :not_found} or noun || nil ?

In my own historical work I’ve generally followed along with common Phoenix generator style of building out functions like get_noun/1 that return the noun or nil but moving forward I think I’ll be preferring fetch_noun/1 functions that use an :ok / :error tuple style return type.

The primary reason is expressiveness in the crash logs. Eventually there will be some crash and the stacktrace is going to show nil being passed into some function, and the function having an expectation of a real value type. In those moments it can take some time to understand where the hell nil is coming from. I think an error like noun_not_found will be more helpful.

I want to start keeping track of these personal preferences and so today I’ve also made a new guide for the Franklin project documenting Code Style: Context Accessors. There is some more background and reasoning about my preferences inside should you be interested.

While that guide expresses a preference towards fetch_noun/1 and the :ok / :error tuple return type, it also acknowledges that it might be helpful and supportive for the context to offer multiple accessor functions allowing the call sites to use whichever one is more appropriate. ` How about yourself? What return type do you prefer and why? Let me know.