> For AI agents: the complete documentation index is available at https://massaman.dev/llms.txt, the full documentation bundle is available at https://massaman.dev/llms-full.txt.

# partitionResults

Separate an array of Results into success values and errors. Every outcome is retained, in its original order within each group. Similar to Rust's `itertools::Itertools::partition_result`, but returns named fields rather than a tuple.

## Usage

### `partitionResults(results)`

```typescript
import { err, ok, partitionResults } from 'massaman/control'

const invalidEmail = new Error('invalid email')
const missingName = new Error('missing name')

const { values, errors } = partitionResults([
  ok({ id: '1' }),
  err(invalidEmail),
  err(missingName),
  ok({ id: '4' }),
])
// values: [{ id: '1' }, { id: '4' }]
// errors: [invalidEmail, missingName]

partitionResults([])
// { values: [], errors: [] }
```

#### Parameters


resultsreadonly Result<T, E>[]required

The already-created Results to separate. Accepts readonly arrays and does not mutate inputs.

#### Returns

```typescript
{ values: T[]; errors: E[] }
```

A plain object, not a Result. Both arrays are new; their elements retain the original value and error references. Typed error fields and distinct error unions are preserved, with no normalization. An all-success input has an empty errors array; an all-failure input has an empty values array. Successful `null` and `undefined` values stay in `values`.

#### Batch processing

```typescript
const { values, errors } = partitionResults(rows.map(parseRow))
```

Use this when partial success is meaningful: process valid rows while reporting every rejected row. If you need source positions, attach row metadata to the value or domain error before partitioning; cross-group positions are not retained automatically.

All input operations have already executed. This helper neither catches exceptions nor awaits Promises. Wrap unsafe row parsing with `attempt`, or await asynchronous Results before partitioning.

## See also

- [`collectResults`](https://massaman.dev/reference/control/collectResults.md) — require all successes, returning only the first failure
- [`isOk`](https://massaman.dev/reference/control/isOk.md) / [`isErr`](https://massaman.dev/reference/control/isErr.md) — narrow individual Results
- [Result & Errors](https://massaman.dev/concepts/result.md)