Index - O
| odd | SimpleH.Core, SimpleH |
| one | SimpleH.Core, SimpleH |
| oneOf | SimpleH.Parser |
| option | SimpleH.Parser |
| or | SimpleH.Foldable, SimpleH.Traversable, SimpleH |
| Ord | SimpleH.Core, SimpleH |
| Orderable | SimpleH.Core, SimpleH |
| Ordering | SimpleH.Core, SimpleH |
| OrdList | |
| 1 (Type/Class) | SimpleH.Core, SimpleH |
| 2 (Data Constructor) | SimpleH.Core, SimpleH |
| otherwise | SimpleH.Core, SimpleH |