It’s fine but it also requires an operator for module combo. Will it be
+?
Does it actually require it? it could use an interface similar to
__functor.
Actually I somehow feel most of the proposal can be implemented in plain
nix right now.
The only thing I think we miss for this is ways to associate (and query)
arbitrary metadata to an attrset key, including one that is not
associated with a value. With this I think everything proposed can be
done with __functor-based magic.
And I don’t think adding metadata and a builtin to an attrset key
actually requires a major version bump, if the metadata syntax is chosen
to be backwards-compatible?
Also, I feel that doing things this way makes the language more powerful
and opens up more possibilities than hardcoding merge etc. in the
extensible attrsets.
Now, maybe I’m missing a point 