Index - O
| odd | Prelate |
| on | Prelate |
| OnDecodeError | Prelate |
| OnError | Prelate |
| onException | Prelate |
| optional | Prelate |
| or | Prelate |
| Ord | Prelate |
| ord | Prelate |
| Ordering | Prelate |
| orElse | Control.Concurrent.STM, Control.Monad.STM |
| otherwise | Prelate |
| Output | Prelate |
| output | Prelate |
| OutputPipe | Process, Polysemy.Process |
| outputToIOMonoid | Prelate |
| outputToIOMonoidAssocR | Prelate |
| outputToWriter | Prelate |
| over | Prelate |