Standard library / JSON · on the one-page reference

JSON

Experimental — new, manually tested rather than conformance-suite covered.

Automatic (de)serialization for Lumen's record types, so no custom per-field (de)serialization code was needed. Deviation from Node: JSON.parse<T> takes an explicit type argument (there's no dynamic/any value to hand back). Invalid input throws a catchable Error (like JS's SyntaxError) — wrap it in try/catch. Works for primitives, named record types, and arrays of either; Map/Set/tuples are not supported as T this pass (see the roadmap).

stringify parse

`JSON.stringify(value)`

T → string — T inferred from value, the same as every other Lumen builtin. Empty string on an encode failure.

type Person = { name: string, age: int, active: bool };
const p: Person = { name: "Ada", age: 30, active: true };
console.log(JSON.stringify(p)); // {"name":"Ada","age":30,"active":true}

`JSON.parse<T>(text)`

string → T — the first explicit type argument on a namespace call in Lumen (every other generic call site is a free function/class). Throws a catchable Error on invalid input.

type Person = { name: string, age: int, active: bool };
const p: Person = JSON.parse<Person>('{"name":"Grace","age":45,"active":false}');
console.log(p.name); // Grace

try {
  const broken: Person = JSON.parse<Person>("not json");
} catch (e) {
  console.log(e.message); // JSON.parse: invalid JSON (...)
}

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