> For the complete documentation index, see [llms.txt](https://demystifyfp.gitbook.io/fstoolkit-errorhandling/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://demystifyfp.gitbook.io/fstoolkit-errorhandling/fstoolkit.errorhandling.icedtasks/index-1/singleton.md).

# singleton

### CancellableTaskValidation.singleton

Namespace: `FsToolkit.ErrorHandling`

Lifts a value into a `CancellableTaskValidation`, wrapping it as an `Ok` result. This is the primary way to create a successful `CancellableTaskValidation` value.

### Function Signature:

```fsharp
'item -> CancellableTaskValidation<'item, 'Error>
```

### Examples

#### Example 1

```fsharp
let result : CancellableTaskValidation<int, string> =
  CancellableTaskValidation.singleton 42
```

#### Example 2

Using `singleton` inside a pipeline to return a validated value:

```fsharp
let validateAge (age: int) : CancellableTaskValidation<int, string> =
  if age >= 0 then CancellableTaskValidation.singleton age
  else CancellableTaskValidation.error "Age must be non-negative"
```