Project Scalar Literal Constructors v1

Status: implemented bounded profile; HOSTED GREEN under the v0.4.0 release baseline. Historical local, authoring-time, ignored, or separately provisioned observations below retain their narrower scope; public promotion and broader product completion remain separately gated.

Audience: agent builders, compiler contributors, and reviewers.

The candidate expression grammar and exact literal defaults for signature evolution expose the complete built-in Copy-scalar vocabulary. The existing five forms retain their wire representation:

{"kind":"i64","value":-1}
{"kind":"i32","value":-1}
{"kind":"u8","value":255}
{"kind":"usize","value":42}
{"kind":"bool","value":true}

Three additive forms carry characters and floats without relying on JSON number precision, host float parsing, source escapes or surrogate handling:

{"kind":"char","scalar":"0001f600"}
{"kind":"f32","bits":"3dcccccd"}
{"kind":"f64","bits":"3fb999999999999a"}

scalar is exactly eight lowercase hexadecimal digits. Its decoded u32 must be one Unicode scalar value, so surrogate code points and values above 0010ffff reject. The spelling encodes a number for transport; it is not source text or a JSON character. Canonical source formatting escapes NUL, controls, quotes, backslashes and non-ASCII values. Reparsing must recover the same scalar without normalization.

f32.bits and f64.bits are exactly eight and sixteen lowercase hexadecimal digits respectively and carry the complete IEEE-754 representation. Only finite values are constructible. Positive and negative zero, subnormals, ordinary finite values and the maximum finite magnitudes are admitted; every infinity and NaN encoding rejects. Nonfinite values cannot be written as source literals. Accepting them here would break canonical source replay.

Source parses a leading minus as unary negation rather than part of a float literal. A sign-bit-set finite request therefore lowers to the existing unary negation node over a positive-magnitude float literal. This includes negative zero. The generated unary node consumes the shared expression-node budget and the ordinary depth bound. Positive encodings lower directly. Canonical formatting and reparsing must recover this structure and its exact magnitude bits; checked evaluation recovers the originally requested signed bits. This route does not change the lexer, parser, formatter, arithmetic or IEEE rules.

Composition and scope

All eight scalar forms compose through recursive function-body, selected-body, contract and typed-hole expressions. The legacy append-signature form and the ordered signature mapping form may add any of the eight by-value types with an exact matching literal default. Caller staging, argument order, failure selection, ownership checks and complete candidate replay remain unchanged.

This shared literal grammar does not widen every feature that happens to use a scalar. Record-field defaults remain the explicit five-kind i64/i32/u8/usize/bool surface. Diagnostic literal retagging remains the explicit four integer kinds. Computed signature argument expressions keep their separately admitted type selectors. Function/data declaration schemas, generic arguments, extraction, movement and target profiles are unchanged.

The forms construct existing AST and HIR values. They do not add source syntax, Graph schemas, coercions, imports, capabilities, runtime operations or publication authority. Structural discovery is not proof that a literal fits the selected expression type, contract phase, effect inventory, caller or target profile. Formatting, source reparsing and independent full-Project admission remain authoritative.

Schemas, limits and failure

Constructor schemas close every object to the fields shown above. Fixed-width lowercase patterns make request validation deterministic in generated TypeScript, Python and Rust clients. Catalogues and full and compact hole contexts advertise char, f32 and f64 alongside the prior scalar kinds. No generated-client payload cap is raised.

Each wire literal consumes its ordinary root node. A negative float consumes one additional generated unary node. The existing 4,096-node/64-depth constructor bounds, enclosing JSON and Semantic Change limits, Project source limits and transport limits remain active. These are structural bounds, not a total memory or execution guarantee.

Malformed object shape, wrong field type, wrong width, uppercase or nonhex digits, invalid Unicode scalars and nonfinite float encodings use SPX-G225. Generated-node or other construction capacity excess uses SPX-G226. Ordinary source type, ownership, contract and target diagnostics follow construction. Every failure leaves live source, existing candidates and sibling drafts unchanged.

Evidence

Candidate regressions and protocol regressions are implemented. They cover exact Unicode and IEEE boundaries, signed-float lowering, canonical source and Graph/HIR replay, expression and hole composition, both signature-evolution forms, malformed input, recovery and the unchanged narrower record/diagnostic grammars. The existing generated Rust client serialized-size gate remains unchanged and is included in the hosted-green release corpus.

No compiler, client, interpreter, backend, test or quality gate was executed for this addition. The graph-operational programme remains Partial.