Having worked with erlang for some time now, https://www.erlang.org/eeps/eep-0049 is _very exciting_ to me. One of the issues that I have with the codebase that I'm in is deep nesting, which could be solved with this feature. Very compelling.
"This is the most general control flow in this document, being fully flexible with regards to which values it can handle. This was done in part because there is not a strong norm regarding error or valid values in either the Erlang nor Elixir APIs, at least compared to other languages here.
This high level of flexibility has been criticized in some instances as being a bit confusing: it is possible for users to make error-only flows, success-only flows, mixed flows, and consequently the ˋelseˋ clause can become convoluted."