Jadpo is experimental and not ready for production. These docs follow the compiler's main branch as of 5 Nov 2026. What's built · Install 0.3.0
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ReferenceErrors

ErrorsReads and writes · rule

query.result_rule

Query result type has rules across its fields.

Area 6, Reads and writes; not declinable; the next step is usually the agent's.

example
type LeafCount = Int {    min: 1    max: 5000}entity Book {    id: Uuid    leaves: LeafCount}type ThickBook = Output {    pick: [Book.id, Book.leaves]    rule thick: leaves > 1000}query thick_books() -> List<ThickBook> {    from: Book    order: [Book.id asc]    limit: 20}
jadpo checkcheck failed: 1 error, 1 file

error thick_books returns ThickBook, whose rule thick no read can check

--> main.jadpo:16:24

   |16 | query thick_books() -> List<ThickBook> {   |                        ^^^^^^^^^^^^^^^ `ThickBook` has rules
reason
A rule across an object's fields is checked whenever a value is made, and a value that breaks it is a failure an attempt maps; a query makes ThickBook from stored records with no attempt around it, so its result type has no rules across its fields.
next
Return a type without rules, and build ThickBook from it with attempt where its rules are checked (agent)
rule
query.result_rule
help
https://jadpo.dev/docs/errors/query.result_rule

A query that needs only the thick books says so in where:, and a type with the rule is built from its result where a failure can be mapped.

Markdown for agents: /docs/errors/query.result_rule.md.Built from Jadpo main at aee2e8f.