Index - O
| odd | Core.Util |
| on | Core.Util |
| oneBits | Core.Util |
| onException | Core.Util |
| Op | |
| 1 (Type/Class) | Core.Util |
| 2 (Data Constructor) | Core.Util |
| Open | Core.Util |
| open | Core.Toml |
| openBinaryFile | Core.Util |
| openBinaryTempFile | Core.Util |
| openBinaryTempFileWithDefaultPermissions | Core.Util |
| openFile | Core.Util |
| OpenIn | Core.Util |
| OpenPunctuation | Core.Util |
| openTempFile | Core.Util |
| openTempFileWithDefaultPermissions | Core.Util |
| openWith | Core.Util |
| optional | Core.Util |
| or | Core.Util |
| Ord | Core.Util |
| ord | Core.Util |
| Ord1 | Core.Util |
| Ord2 | Core.Util |
| Ordering | Core.Util |
| OtherError | Core.Util |
| OtherLetter | Core.Util |
| OtherNumber | Core.Util |
| OtherPunctuation | Core.Util |
| OtherSymbol | Core.Util |
| otherwise | Core.Util |
| outputNL | Core.Util |
| Overflow | Core.Util |