Re: Equivalence of hierarchical and flat data formats

What about round-tripping in both directions? (question not a comment).

On Wed, Jul 27, 2022 at 5:25 AM Michael Kay <[email protected]> wrote:

> To expand on this, the first level of equivalence between two data models
> is to show that there's a one-to-one correspondence between their value
> spaces. That's tricky to achieve, but feasible. To do a perfect one-to-one
> correspondence, you tend to find that the representation in one of the
> models is rather contorted and unnatural, and in practice people tend to
> prefer mappings that are imperfect but more natural - we see that all the
> time with XML-to-JSON mappings.
>
> The second level of equivalence is to show that there's a one-to-one
> correspondence between the state transitions (updates) supported by the two
> models. That's very much harder.
>
> Michael Kay
> Saxonica
>
>