| UHC | Distribution.Compiler, Distribution.Simple.Compiler, Distribution.Simple |
| uhcProgram | Distribution.Simple.Program.Builtin, Distribution.Simple.Program |
| Unambiguous | Distribution.Simple.PackageIndex |
| UnboxedTuples | Language.Haskell.Extension, Distribution.Simple |
| UndecidableInstances | Language.Haskell.Extension, Distribution.Simple |
| UnicodeSyntax | Language.Haskell.Extension, Distribution.Simple |
| unionVersionIntervals | Distribution.Version, Distribution.Simple |
| UnionVersionRanges | Distribution.Version, Distribution.Simple |
| unionVersionRanges | Distribution.Version, Distribution.Simple |
| UnknownBuildType | Distribution.PackageDescription |
| UnknownExtension | Language.Haskell.Extension, Distribution.Simple |
| UnknownLanguage | Language.Haskell.Extension, Distribution.Simple |
| UnknownLicense | Distribution.License, Distribution.Make, Distribution.Simple |
| UnliftedFFITypes | Language.Haskell.Extension, Distribution.Simple |
| unlit | Distribution.Simple.PreProcess.Unlit |
| unregHook | Distribution.Simple.UserHooks, Distribution.Simple |
| unregister | |
| 1 (Function) | Distribution.Simple.Program.HcPkg |
| 2 (Function) | Distribution.Simple.Register |
| unregisterCommand | Distribution.Simple.Setup |
| unregisterInvocation | Distribution.Simple.Program.HcPkg |
| unsupportedExtensions | Distribution.Simple.Compiler, Distribution.Simple |
| unsupportedLanguages | Distribution.Simple.Compiler, Distribution.Simple |
| updatePackageDescription | Distribution.PackageDescription |
| updateProgram | Distribution.Simple.Program.Db, Distribution.Simple.Program |
| UpperBound | |
| 1 (Type/Class) | Distribution.Version, Distribution.Simple |
| 2 (Data Constructor) | Distribution.Version, Distribution.Simple |
| usedExtensions | Distribution.PackageDescription |
| UserHooks | |
| 1 (Type/Class) | Distribution.Simple.UserHooks, Distribution.Simple |
| 2 (Data Constructor) | Distribution.Simple.UserHooks, Distribution.Simple |
| userMaybeSpecifyPath | Distribution.Simple.Program.Db, Distribution.Simple.Program |
| UserPackageDB | Distribution.Simple.Compiler, Distribution.Simple |
| UserSpecified | Distribution.Simple.Program.Types, Distribution.Simple.Program |
| userSpecifiedArgs | Distribution.Simple.Program.Db, Distribution.Simple.Program |
| userSpecifyArgs | Distribution.Simple.Program.Db, Distribution.Simple.Program |
| userSpecifyArgss | Distribution.Simple.Program.Db, Distribution.Simple.Program |
| userSpecifyPath | Distribution.Simple.Program.Db, Distribution.Simple.Program |
| userSpecifyPaths | Distribution.Simple.Program.Db, Distribution.Simple.Program |