To me GitHub - CargoSense/fable: Your events have a story to tell. · GitHub is still the most simple introduction one can have to event sourcing on elixir. It easily retrofits onto a regular ecto architecture, it’s 1000 loc you can read in like 15 minutes and most of it is simple boilerplate - if you can do phoenix with ecto you can understand the fable codebase. As with e.g. commanded you want to skip ProcessManager. Comparatively commanded feels like a kubernetes in terms of complexity in setup - useful, with lots of the mentioned sidequests.
I personally am a big fan of discovering concepts from first principle, so maybe that’s why I like the approach of fable so much. It shows you how to store decisions with events and updating an aggregate without needing to name those things. Once you got to see how such a system works then you can start giving the pieces names like the commands, aggregates, projections whatnot. Once the basic idea is explained you can start getting into all the additional ideas necessary to cover the sharp edges a more naive implementation might not care for or run into.
To turn this into the direction of Must. I like the idea of a more generalizable system, but it imo does suffer from e.g. expecting “Commands” where a user might not know what to make of the word command. At least for the context of teaching I’d personally stay with fable and maybe then update to Must if it eventually delivers a more featureful step beyond fable before needing to take the step to e.g. commanded.
