| ObjectiveC | Distribution.Simple.CCompiler |
| ObjectiveCPlusPlus | Distribution.Simple.CCompiler |
| objExtension | Distribution.Simple.BuildPaths |
| oldExtensions | Distribution.PackageDescription |
| OpenBSD | Distribution.System |
| OptArg | Distribution.Simple.Command |
| optArg | Distribution.Simple.Command |
| optArg' | Distribution.Simple.Command |
| OptDescr | Distribution.Simple.Command |
| OptFlags | Distribution.Simple.Command |
| OptimisationLevel | Distribution.Simple.Compiler, Distribution.Simple |
| option | |
| 1 (Function) | Distribution.Compat.ReadP |
| 2 (Function) | Distribution.Simple.Command |
| optional | Distribution.Compat.ReadP |
| OptionBool | Distribution.TestSuite |
| optionDefault | Distribution.TestSuite |
| OptionDescr | |
| 1 (Type/Class) | Distribution.TestSuite |
| 2 (Data Constructor) | Distribution.TestSuite |
| optionDescr | Distribution.Simple.Command |
| optionDescription | Distribution.TestSuite |
| OptionEnum | Distribution.TestSuite |
| OptionField | |
| 1 (Type/Class) | Distribution.Simple.Command |
| 2 (Data Constructor) | Distribution.Simple.Command |
| OptionFile | Distribution.TestSuite |
| optionFileExtensions | Distribution.TestSuite |
| optionFileIsDir | Distribution.TestSuite |
| optionFileMustExist | Distribution.TestSuite |
| optionName | |
| 1 (Function) | Distribution.TestSuite |
| 2 (Function) | Distribution.Simple.Command |
| OptionNumber | Distribution.TestSuite |
| optionNumberBounds | Distribution.TestSuite |
| optionNumberIsInt | Distribution.TestSuite |
| OptionRngSeed | Distribution.TestSuite |
| Options | Distribution.TestSuite |
| options | |
| 1 (Function) | Distribution.TestSuite |
| 2 (Function) | Distribution.PackageDescription |
| OptionSet | Distribution.TestSuite |
| OptionString | Distribution.TestSuite |
| optionStringMultiline | Distribution.TestSuite |
| OptionType | Distribution.TestSuite |
| optionType | Distribution.TestSuite |
| optionVerbosity | Distribution.Simple.Setup |
| optKeepTempFiles | Distribution.Simple.Utils |
| orEarlierVersion | Distribution.Version, Distribution.Simple |
| orLaterVersion | Distribution.Version, Distribution.Simple |
| OS | |
| 1 (Type/Class) | Distribution.System |
| 2 (Data Constructor) | Distribution.PackageDescription |
| OSVar | Distribution.Simple.InstallDirs, Distribution.Simple.LocalBuildInfo |
| OSX | Distribution.System |
| OtherArch | Distribution.System |
| OtherCompiler | Distribution.Compiler, Distribution.Simple.Compiler, Distribution.Simple |
| otherExtensions | Distribution.PackageDescription |
| otherLanguages | Distribution.PackageDescription |
| OtherLicense | Distribution.License, Distribution.Make, Distribution.Simple |
| otherModules | Distribution.PackageDescription |
| OtherOS | Distribution.System |
| OtherRepoType | Distribution.PackageDescription |
| OverlappingInstances | Language.Haskell.Extension, Distribution.Simple |
| OverloadedLists | Language.Haskell.Extension, Distribution.Simple |
| OverloadedStrings | Language.Haskell.Extension, Distribution.Simple |