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Bigint negative

bigintNegative validates that a value is a string representing a strictly negative BigInt.

It enforces strict bigint‑string semantics: the value must be a string, must parse successfully as a BigInt literal, and must be strictly less than 0n. If any condition fails, the rule emits a single validation event. Otherwise, it produces no validation output.

Signature

Through the API:

.bigintNegative();

And internally:

export const bigintNegative: ValidationRule
(value: unknown, path: FieldPath) => Promise<ReadonlyArray<JaneEvent>>

Events

Event code Description
bigint.not.string Value is not a string.
bigint.not.bigint String is not a valid bigint literal.
bigint.not.negative Parsed bigint is greater than or equal to zero.

Design rationale

  • Enforces strict bigint‑string validation with no coercion or normalization.
  • Rejects non‑string values early with a structural‑type diagnostic.
  • Treats empty strings and malformed literals as invalid bigint values.
  • Uses JavaScript’s BigInt() constructor for canonical parsing.
  • Ensures negativity is explicit: only values < 0n are accepted.
  • Emits exactly one event per failure for clarity and composability.
  • Pure, total, async‑compatible, and returns a readonly array of JaneEvent objects.
  • Preserves the provided path and supports pipeline‑level userMessage overrides.

Invoke

bigintNegative runs only when explicitly included in a boundary or pipeline. It does not run automatically.

The rule activates when:

  • The value is any JavaScript value.
  • If the value is not a string → emits bigint.not.string.
  • If the string is empty or cannot be parsed by BigInt → emits bigint.not.bigint.
  • If the parsed bigint is greater than or equal to 0n → emits bigint.not.negative.
  • Otherwise → returns an empty result set.

Examples

Valid — negative bigint string

await bigintNegative("-42", "$");
// → []

Invalid — not a string

await bigintNegative(123, "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "bigint.not.string",
//       path: "$",
//       ...
//     }
//   ]

Invalid — malformed bigint literal

await bigintNegative("01", "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "bigint.not.bigint",
//       path: "$",
//       ...
//     }
//   ]

Invalid — bigint is zero or positive

await bigintNegative("0", "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "bigint.not.negative",
//       path: "$",
//       ...
//     }
//   ]

await bigintNegative("42", "$");
// → [
//     JaneEvent{
//       kind: "error",
//       code: "bigint.not.negative",
//       path: "$",
//       ...
//     }
//   ]