I'm the author of xo. I appreciate the reference here, but that's not really what xo does. It generates all boilerplate for you directly based on whatever is defined by the database. It doesn't do anything with YAML, nor does it generate a SQL schema. xo does have 2 templates that _generates_ YAML and _generates_ SQL queries to recreate the schema, but the only input you can give xo is an active database.