You're talking about pure validation, though. dry-schema and the like, though, are more like in-memory ETL libraries for form data: they don't just describe a v

You're talking about pure validation, though. dry-schema and the like, though, are more like in-memory ETL libraries for form data: they don't just describe a valid parameters shape, but also what — and how — to extract from those parameters, and an (implied) data-structure shape + typings to put the results into. I can see how you could generate the Extract step of an ETL process (i.e. a validation specification) purely from the form HTML itself. But I'm not sure where you'd stuff the information required to do the Transform or Load steps. It isn't cleanly separable into per-component data attributes.