5. Scope: supported tiers and current boundaries
Triptych's expressiveness is layered. The grammar tier remains small enough for generated reconciliation proofs, constraints can narrow its language, and value escapes can return arbitrary types. This chapter describes the supported surface and the boundary of the current compiler.
Supported now. Triptych generates readable specifications, executable parsers, and
reconciliation proofs for acyclic, non-recursive grammars built from literals, finite
alternatives, optional items, sign, built-in digit, hexadecimal, and bit runs, inclusive
ASCII ranges, separated repetition, and delimiter-bounded final payloads whose exact width is
computed from earlier captures. Values and constraints may use the
analyzable DSLs or user-supplied escape functions. Declared external parsers and printers receive
explicit proof contracts.
Not currently supported. The generated grammar surface does not directly support the
arbitrary character predicates or unseparated repetition needed by general Base64,
delimiter-free or internal capture-dependent boundaries, or recursive formats such as JSON,
s-expressions, and Cedar policies. The scanner architecture supports a header-selected tail
grammar through Triptych.scanDependent, and the Graph6 example exercises that API, but
automatic specification, view, and derivation generation for that general staged form remains
future work.