| octDigit | Streamly.Internal.Unicode.Parser, Streamly.Unicode.Parser |
| one | |
| 1 (Function) | Streamly.Internal.Data.Parser, Streamly.Data.Parser |
| 2 (Function) | Streamly.Internal.Data.Fold, Streamly.Data.Fold |
| oneEq | Streamly.Internal.Data.Parser |
| oneNotEq | Streamly.Internal.Data.Parser |
| oneOf | Streamly.Internal.Data.Parser, Streamly.Data.Parser |
| onException | |
| 1 (Function) | Streamly.Internal.Data.Fold |
| 2 (Function) | Streamly.Internal.Data.Unfold |
| 3 (Function) | Streamly.Internal.Data.Stream, Streamly.Internal.Data.Stream.StreamD, Streamly.Data.Stream |
| openAt | Streamly.Internal.FileSystem.Posix.File |
| openBinaryFile | Streamly.Internal.FileSystem.Posix.File |
| openConstructor | Streamly.Internal.Data.MutByteArray |
| openDirStream | Streamly.Internal.FileSystem.Posix.ReadDir |
| openDirStreamCString | Streamly.Internal.FileSystem.Posix.ReadDir |
| openFile | |
| 1 (Function) | Streamly.Internal.FileSystem.File.Common |
| 2 (Function) | Streamly.Internal.FileSystem.Posix.File |
| OpenFlags | |
| 1 (Type/Class) | Streamly.Internal.FileSystem.Posix.File |
| 2 (Data Constructor) | Streamly.Internal.FileSystem.Posix.File |
| or | Streamly.Internal.Data.Fold, Streamly.Data.Fold |
| ordering | |
| 1 (Function) | Streamly.Internal.Data.Binary.Parser |
| 2 (Function) | Streamly.Internal.Data.Binary.Stream |
| ordNub | Streamly.Internal.Data.Stream, Streamly.Internal.Data.Stream.StreamD |
| OsCString | Streamly.Internal.FileSystem.Path |
| OsWord | Streamly.Internal.FileSystem.Path, Streamly.FileSystem.Path |
| outerJoin | Streamly.Internal.Data.Stream, Streamly.Internal.Data.Stream.StreamD |
| OuterLoop | Streamly.Internal.Data.Producer |
| outerOrdJoin | Streamly.Internal.Data.Stream, Streamly.Internal.Data.Stream.StreamD |
| outerSortedJoin | Streamly.Internal.Data.Stream, Streamly.Internal.Data.Stream.StreamD |
| outputDoorBell | Streamly.Internal.Data.SVar.Type |
| outputDoorBellFromConsumer | Streamly.Internal.Data.SVar.Type |
| outputHeap | Streamly.Internal.Data.SVar.Type |
| outputQueue | Streamly.Internal.Data.SVar.Type |
| outputQueueFromConsumer | Streamly.Internal.Data.SVar.Type |