Release v0.6.0 · panproto/didactic

Added

Field annotations of the form A | B where both A and B are TaggedUnion roots are now classified as a multi-root discriminated union. The two arms must share the same discriminator field name (checked at class-creation time) and their discriminator-value sets must be disjoint (checked lazily, only on encode/decode of an actually colliding value, so a model whose union-typed field is never encoded with a colliding variant remains usable). Encode and decode both consult the live merged variant registry, so variants registered after the field's parent class is classified participate fully. (#30)
@dx.model_validator(mode="after") decorates a class method as a class-level validator that receives the constructed instance and runs after every per-field validator and every __axioms__ check. raise ValueError / raise TypeError from the body surfaces as a ValidationError entry with type="validator_error" and empty loc. Multiple model validators on one class collect into a single error. Subclass inheritance and the silent-shadow override-without-marker policy work the same as for @validates. Use this for cross-field invariants that aren't expressible in the __axioms__ surface syntax. The shape mirrors Pydantic v2's @model_validator(mode="after"). (#31)

The axiom evaluator now resolves length xs (panproto's long-form length builtin) the same as len xs. Both compile to Python len(...). (#31)
isNone / isNull / isSome / isJust builtins resolve to the obvious value is None / value is not None predicates in axiom expressions. The Python-friendly is null / is not null preprocessor rules from v0.5.1 already covered the most common spelling; these add the explicit-call form for axioms that prefer it. (#31)

docs/guide/unions.md documents the union-of-TaggedUnion-roots shape with the disjoint-values requirement spelled out.
docs/guide/validators.md documents @dx.model_validator and the cross-field-invariants decision tree (axiom for surface-syntax expressible, model_validator for Python-needed).