Index - O
| objectName | Protolude |
| odd | Protolude |
| on | Protolude |
| OnDecodeError | Protolude |
| one | Protolude |
| OnError | Protolude |
| onException | Protolude |
| openFile | Protolude |
| Option | |
| 1 (Data Constructor) | Protolude |
| 2 (Type/Class) | Protolude |
| option | Protolude |
| optional | Protolude |
| or | Protolude |
| orAlt | Protolude |
| Ord | Protolude |
| ord | Protolude |
| Ordering | Protolude |
| ordNub | Protolude |
| orElse | Protolude |
| orEmpty | Protolude |
| otherwise | Protolude |
| Overflow | Protolude |
| overflowError | Protolude |