Introducing YAMLSchema
YAML has always needed a schema language. Of course there have been many attempts to create a schema language for YAML, but never an official one from the YAML organization.
JSON Schema has been around for a while and is widely used not only for JSON, but also for YAML, which makes sense since YAML is a superset of JSON. Sadly JSON Schema requires a lot of definition for not so much effect. YAML is all about getting the most out of the least, so it is time for a schema language that is designed for YAML.
YAMLSchema is a new schema language for YAML (and JSON) data. While it is still in its early stages, it is intended to be a very rich, expressive, extensible, easy-to-read, and easy-to-write schema language. Like YAML is a superset of JSON, YAMLSchema intends to be a superset of JSON Schema. Not a syntactic superset, but a semantic superset.