Index - O
| odd | Language.Parser, Language.Format |
| one | Language.Parser, Language.Format |
| oneOf | Language.Parser, Language.Format |
| oneOfSet | Language.Parser, Language.Format |
| only | Language.Parser, Language.Format |
| option | Language.Parser, Language.Format |
| option' | Language.Parser, Language.Format |
| optional | Language.Parser, Language.Format |
| optionMaybe | Language.Parser, Language.Format |
| optionMaybe' | Language.Parser, Language.Format |
| or | Language.Parser, Language.Format |
| Ord | Language.Parser, Language.Format |
| OrderedMap | Language.Parser, Language.Format |
| Ordering | Language.Parser, Language.Format |
| OrdList | |
| 1 (Data Constructor) | Language.Parser, Language.Format |
| 2 (Type/Class) | Language.Parser, Language.Format |
| otherwise | Language.Parser, Language.Format |