Can't say I love the notation, but indeed that is type annotations. I guess neither "yaml type hints" nor "yaml type annotations" are the right query. Had to search explicitly for "yaml tags".
The neat thing is that you can use tags to represent custom data structures or functions. For example, AWS Cloudformation uses YAML tags as a shorthand for template functions [0].
I've never seen typed yaml, this is wild.
Can't say I love the notation, but indeed that is type annotations. I guess neither "yaml type hints" nor "yaml type annotations" are the right query. Had to search explicitly for "yaml tags".