pub fn build(v: &Value) -> Result<Spec, ExprError>Expand description
Read the declarative JSON of a shape, what Schema::json writes: every
string is an expression (the example of a key expression is a value, so
a string there is the string itself), and a "$$" key applies an
expression to the object that holds it, with the "$$0", "$$1", …
sidecars beside it as the arguments an expression cannot spell inline.