Embedded yaml

How might a programming language support embedded YAML?

A number of language's support HERE Documents. So that is a traditional way to embed YAML, e.g.

  yaml = <<-YAML
    a: 1
    b: 2
  YAML

But this a very superficial type of integration. It could be taken a step further with:

  yaml = ---
    a: 1
    b: 2
    ...

But this really isn't much different from using a HERE doc, so why bother? Taking another step I purpose an embedded evaluation syntax.

  a = 1

  yaml = ---
    a: <-{ a }
    b: <-{ a + a }
    ...

Notice that this is not as simple a string interpolation. The actual return value of the evaluation is serialized into the YAML.

This would be part of the specification specifically for embedded applications.