parseIterable

Attempts to parse a value into an iterable. This parser is strict: the value must already implement a callable [Symbol.iterator] method. No coercion is performed. It mirrors the behavior of validateIterable but returns a structured ParseResult.

It never throws and never mutates input.

Signature

function parseIterable<T = unknown>(value: unknown): ParseResult<Iterable<T>>

Parameters

Returns

• ok: true, value: Iterable<T>, issues: []: When the value is iterable.
• ok: false, value: null, issues: string[]: When the value is not iterable.

Behavior

• Uses isIterable internally.
• Accepts:
• Arrays.
• Strings.
• Maps and Sets.
• Typed arrays.
• Generators.
• Custom objects with a callable Symbol.iterator.
• Rejects:
• null and undefined.
• Numbers, booleans.
• Plain objects without an iterator.
• Objects with non-callable iterators.
• Never throws and never mutates input.

Examples

parseIterable([1, 2, 3])
// { ok: true, value: [1, 2, 3], issues: [] }

parseIterable("abc")
// { ok: true, value: "abc", issues: [] }

parseIterable({ a: 1 })
// { ok: false, value: null, issues: ["Value must be iterable"] }

parseIterable(null)
// { ok: false, value: null, issues: ["Value must be iterable"] }

Notes

• This parser is intentionally strict and does not attempt to normalize or coerce values into iterables.
• For coercive behavior, use normalizeIterable instead.
• Suitable for strict protocol checks before further validation or domain logic.