literal - API reference

API reference › @evolu/common › Type › literal

function literal<Expected>(
  expected: ValidateLiteral<Expected>,
): LiteralType<Expected>;

Defined in: packages/common/src/Type.ts:3392

Literal Type.

String, Number, BigInt, and Boolean literal Types are children of their corresponding primitive Types and accept the widened primitive through from.parent. The expected value must have one exact literal type. Validation uses ===, so -0 matches 0.

In templateLiteralParser, use a string Literal Type when the literal should be decoded into the Output Tuple. Use a raw string when it should only frame the canonical string.

Example

import {
  assertEqual,
  assertErr,
  assertOk,
  assertType,
  Data,
  literal,
} from "@evolu/common";

const Ready = literal("ready");

assertType<"ready", typeof Ready.Output>();
assertOk(Ready.fromUnknown("ready"), "ready");
const invalid = Ready.fromUnknown("pending");
assertErr(invalid);
assertType(Data, invalid.error);
assertEqual(invalid.error, {
  type: "Literal",
  expected: "ready",
  value: "pending",
});