Grammar contract

The website is explanatory. The versioned language contract lives in language/v1.

Artifact	Authority
grammar.pest	Canonical syntax grammar
spec/semantics.md	Meaning and validation rules
fixtures/valid/*.qql	Programs that must parse and validate
fixtures/invalid/*.qql	Annotated failures and stable error codes
fixtures/expected/*.json	Canonical qql.ast/v1 output
qql-core::Parser::parse_all	Production full-script parser

The checked-in grammar modules are generated. language/v1/grammar.pest is the only handwritten core syntax grammar; the generated copy under crates/qql-core/grammar must never be edited directly. After a grammar change, regenerate it with qql-grammar-gen and review the complete diff.

Script grammar

script = [ statement, { ";", statement }, [ ";" ] ] ;
statement = query | scroll | count | upsert | update | delete
          | clear-payload | delete-payload | delete-vector
          | create | alter | drop | show ;

Statement surface

Every statement family, including the three SHOW forms:

Family	Grammar production
QUERY ...	query
SCROLL FROM ... LIMIT n	scroll
COUNT FROM ...	count
UPSERT INTO ... VALUES {...}	upsert
UPDATE ... SET PAYLOAD / SET VECTOR	update
DELETE FROM ... WHERE ...	delete
DELETE PAYLOAD field, ... FROM ... WHERE ...	delete-payload
DELETE VECTOR name, ... FROM ... WHERE ...	delete-vectors
CLEAR PAYLOAD FROM ... WHERE ...	clear-payload
CREATE COLLECTION ...	create-collection
CREATE INDEX ON COLLECTION ... FOR field	create-index
ALTER COLLECTION ... WITH <block> (...)	alter-collection
DROP COLLECTION ...	drop-collection
DROP INDEX ON COLLECTION ... FOR field	drop-index
CREATE SHARD KEY 'name' ON COLLECTION ...	create-shard-key
DROP SHARD KEY 'name' ON COLLECTION ...	drop-shard-key
SHOW COLLECTIONS; / SHOW COLLECTION name; / SHOW SHARD KEYS ON COLLECTION name;	show-collections / show-collection / show-shard-keys

Query tail clause order

A query tail accepts each clause at most once, in this order:

USING (a named vector with optional AS <kind>, or HYBRID) → PREFETCH → WHERE → SHARD → PARAMS → SCORE THRESHOLD → GROUP BY [SIZE n] [LOOKUP FROM collection] → WITH PAYLOAD → WITH VECTOR → LIMIT → OFFSET.

The parser rejects a duplicate or out-of-order clause with QQL-PARSE-CLAUSE-ORDER rather than silently reordering it.

Lexical rules

• Keywords are ASCII case-insensitive.
• Identifiers are case-sensitive and preserve spelling.
• Dotted and array payload paths are accepted.
• Strings support single, double, raw, triple, and backtick delimiters.
• -- starts a line comment; block comments do not exist.
• Error spans are zero-based UTF-8 byte ranges [start, end).

Conformance

Check the language fixtures

RUSTC_WRAPPER= cargo run -p qql-conformance -- check language/v1

The conformance runner parses every valid and invalid case through Parser::parse_all and compares valid programs with generated AST snapshots.

Check generated grammar freshness

cargo run -p qql-grammar-gen -- check

Versioning contract

QQL follows MAJOR.MINOR; the current language version is 1.2 while the canonical AST schema is independently fixed as qql.ast/v1.

• Within one major version, every program valid in an earlier minor release must stay valid with the same meaning and canonical AST. A minor release may only make previously invalid source valid by adding syntax.
• Breaking changes (removing syntax, changing clause order, precedence, or an existing fixture's normalization, renaming AST tags, or changing a stable error code) require QQL 2.
• QQL 1.0 has no compatibility parser: pre-v1 SELECT, INSERT, and BOOST are invalid source, not deprecated aliases.
• Deprecated v1 features may be announced but cannot be removed within v1.

See language/v1/spec/versioning.md for the full policy.