---
url: >-
  https://adk.nht.io/api/@nhtio/adk/spooled_artifact/functions/implementsSpoolReader.md
---

# Function: implementsSpoolReader()

```ts
function implementsSpoolReader(value: unknown): value is SpoolReader;
```

Defined in: [lib/contracts/spool\_reader.ts:100](https://github.com/NHTIO/ADK/blob/v1.20260605.0/src/lib/contracts/spool_reader.ts#L100)

Returns `true` if `value` implements the [SpoolReader](../interfaces/SpoolReader.md) interface.

## Parameters

| Parameter | Type      | Description        |
| --------- | --------- | ------------------ |
| `value`   | `unknown` | The value to test. |

## Returns

`value is SpoolReader`

`true` when `value` conforms to the [SpoolReader](../interfaces/SpoolReader.md) interface.

## Remarks

Duck-typed: checks that `value` is non-null with `line`, `byteLength`, `lineCount`, and
`readAll` as callable functions. Does not use `instanceof` — there is no `SpoolReader`
constructor.