Fuyu Policy Language

Write a question#

FPL names Yes/No questions about an account history. Its parser and checker resolve assets and units, subjects and snapshots, disclosure effects and the evidence needed for each answer. The reference evaluator runs a program against a history model you supply.

FPL questions cannot change spending permission. The Pool keeps an opaque note-policy attachment, but it does not read the language or execute its predicates.

Check what the prover supports#

FPL can express questions beyond the current audit circuits. A positive lower bound may need only selected witnesses. An upper bound or absence claim can need complete history in the reference model.

The holder audit compiler accepts a capacity-limited upward subset and rejects programs with unsupported questions. Label reference evaluation as a local, unproven result.

Evaluate the example history#

Run this fixture from the protocol repository root. It evaluates the supplied example history. To produce a zero-knowledge answer, you need the separate audit plan and proof flow.

node dsl/cli.cjs eval dsl/examples/stock-query.fuyu \
  --registry dsl/examples/stock-registry.json \
  --target dsl/examples/stock-target.json \
  --policy dsl/examples/stock-disclosure.fuyu \
  --evidence dsl/examples/stock-history.json

Use the same program on both sides#

The audit plan includes the program's canonical digest, subject, audience, nonce, expiry and finalized snapshot. Prover and verifier must compile it with the same registry, relation configuration and verification-key hashes.

Show the holder the question and what the answer will publish. A holdings or participation proof cannot be used as evidence of a source set, exhaustive history or exclusive contribution to a transaction.