> For the complete documentation index, see [llms.txt](https://osl.mistium.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://osl.mistium.com/packages/utilities/option.md).

# option

> Optional values (`some`/`none`)

Use `option` to model a value that may be present (`some`) or absent (`none`) without relying on `null`.

```javascript
import "osl/option"
```

## Example

```javascript
import "osl/option"

auto value = some(42)
log value.unwrapOr(0)
```

## API reference

### `Option` values

Methods available on `Option` values returned by this package or constructed by the language.

| Method                   | Returns   | Description                                                 |
| ------------------------ | --------- | ----------------------------------------------------------- |
| `value.isSome()`         | `boolean` | Reports whether the option contains a value.                |
| `value.isNone()`         | `boolean` | Reports whether the option is empty.                        |
| `value.unwrap()`         | `T`       | Returns the contained value or fails.                       |
| `value.unwrapOr(def: T)` | `T`       | Returns the contained value or a fallback.                  |
| `value.expect(msg: any)` | `T`       | Returns the contained value or fails with a custom message. |

## Notes

* Standard-library imports accept both `import "osl/option"` and `import "option"`.
* Return values such as `array` and `object` are regular OSL values unless a returned object section says otherwise.