Nikita Shilnikov

@solnic I disagree, return type is required to determine the list of available functions/operators. It's not required for common operators such as `IN` or `=`

@solnic the list of available operators is determined by the expression type: https://github.com/rom-rb/rom-sql/blob/f3ef5817462c4915f37d0523ea2a2ba95c36a9de/lib/rom/sql/type_extensions.rb For instance `json_returning_function(field).json_operator(args)` will be a method missing (or mb some other) error whereas `json::json_returning_function(field).json_operator(args)` will work...

@solnic the actual problem is that it's not obvious how to join a relation through another relation this doesn't work too: ```ruby joined = rom.relation(:bookings).join(rom.relation(:tickets)).join(rom.relation(:passes)) :passes doesn't exist in ROM::AssociationSet...

`multi_insert` is a low-level API that delegates to Sequel directly, you should check its documentation

I reckon Sequel may require some sort of escaping for blob values, though I'm not sure.

Sure.

For me, it would be enough to work only within a single rule run. Though I can see how it can be not immediately obvious. @solnic any thoughts?

`rule.failure?` or something along the lines could be another approach

works for me though `rule.error?`/`rule.failure?` still could be useful

@solnic rules can be quite convoluted, especially in macros. This is the exact need I had when filed this issue. Keeping them simple is not always feasible.