I think the main problem there is checking whether given list is charlist or not, as that may require deep traversal. Also, if we support chartists, then should we also support IO lists? What about charlists with non-ASCII characters in them? Unfortunately, this is place where static typing would be useful, but without that, it may be computationally expensive to check given list on each log message.

This is a bit of a tricky problem given elixir uses :logger nowadays. Idealy one wouldn’t need to care if the host system is an elixir or erlang system to use a logger handler and with some configuration effort you can get there, but it’s not (yet) possible with elixir ootb.

Yes, I noticed this too and had a similar question.

I thought charlists are skipped because validating their contents is not easy / performant enough for such a critical area as logging: e.g. that lists do not contain values other than characters, or that all characters are printable, etc.

But maybe I am wrong an Elixir could indeed implement support for charlists in metadata?