Index - O
| Offset | |
| 1 (Data Constructor) | Foundation |
| 2 (Type/Class) | Foundation |
| on | Foundation |
| oneof | Foundation.Check |
| openFile | Foundation.IO |
| optional | Foundation.Parser |
| or | Foundation.Collection , Foundation |
| Ord | Foundation |
| Ordering | Foundation |
| OS | Foundation.System.Info |
| os | Foundation.System.Info |
| OSX | Foundation.System.Info |
| otherwise | Foundation |
| OutOfBound | Foundation.Array |