Specification · v1

Changelog

v1: ulang-lite 0.1.0

Released 15 October 2026 in ThinkTechHoldings/ulang-git at commit 61af4281ed, MIT licensed.

The v1 contract style: CONTRACT blocks with a typed CONTEXT, an explicit TRIGGER list, sourced GUARANTEE and PROHIBITION clauses, and OBSERVABILITY.
An executable subset, enforced with one stable diagnostic per rejection.
Decisions: PERMIT/DENY and the deciding clause id.
Canonical text, canonical JSON and the SHA-256 contract digest.
Bounds on every input, checked in linear time before parsing.

Number literals with an exponent (1e3, 2.5e-1) are floats. A single = after a name, path or boolean word parses as an assignment and is refused as unsupported[condition-form].

Errata

Known differences between ulang-lite 0.1.0 and the intent of this specification. Each one is checked when the site is built, so this list cannot go stale silently.

	Issue	Effect	Until fixed
E1	A constant's source tag written with a space after `[`, as in `[ SOURCE:P]`, is accepted, but its canonical text is `[SOURCE:[ SOURCE:P]]`, which does not re-parse. Clause tags written this way are already refused (`semantic[clause-id]`).	Such a contract has a digest, but its canonical text is not a valid source.	Write `[SOURCE:id]` with no space after `[`.
E2	Validation reads the top-level `maxConditionDepth` option. `limits.maxConditionDepth` is accepted, but has no effect, and the top-level option is not checked against the 256 ceiling.	Lowering condition depth through `limits` does nothing; a very large top-level value lifts the bound.	Pass `maxConditionDepth` at the top level, between 1 and 256.

Errata E1: a constant tagged [ SOURCE:P] is accepted, but its canonical text does not re-parseerrata-e1

CONTRACT Claim {
  ENFORCEMENT_MODE: enforced
  CONTEXT {
    ENTITIES Request {
      count: int
      region: string
      ready: bool
      ratio: float
    }
    CONSTANTS {
      zero: int == 0 [SOURCE:POLICY]
      cap: int == 25 [ SOURCE:POLICY]
    }
  }
  TRIGGER {
    grant()
  }
  GUARANTEE {
    ENSURE grant() WHEN Request.ready == true [SOURCE:must_be_ready]
  }
  PROHIBITION {
    FORBID grant WHEN Request.count > cap [SOURCE:over_cap]
  }
}

valid Claim 2 clauses · sha256 1ba3c884488e6b7df67a6335f5ba226e18b175b8194f636ac93f8dd3e570a09e

This document

Date	Change
2026-10-15	First publication of the v1 specification on ulang.dev, written against ulang-lite `61af4281ed`.