| UCL_1_0 | Distribution.SPDX.LicenseId, Distribution.SPDX | 
| UHC | Distribution.Compiler | 
| unAbiHash | Distribution.Types.AbiHash, Distribution.Package | 
| UnboxedSums | Language.Haskell.Extension | 
| UnboxedTuples | Language.Haskell.Extension | 
| unComponentId | Distribution.Types.ComponentId, Distribution.Package | 
| uncurry | Distribution.Compat.Prelude | 
| UndecidableInstances | Language.Haskell.Extension | 
| UndecidableSuperClasses | Language.Haskell.Extension | 
| undefined | Distribution.Compat.Prelude | 
| unDefUnitId | Distribution.Types.UnitId, Distribution.Backpack, Distribution.Package | 
| unexpected | Distribution.Compat.Parsing, Distribution.Compat.CharParsing | 
| unFlagAssignment | Distribution.Types.Flag, Distribution.PackageDescription | 
| unFlagName | Distribution.Types.Flag, Distribution.PackageDescription | 
| unfoldr | Distribution.Compat.Prelude | 
| unfoldrM | Distribution.Utils.Generic | 
| UnicodeSyntax | Language.Haskell.Extension | 
| Unicode_DFS_2015 | Distribution.SPDX.LicenseId, Distribution.SPDX | 
| Unicode_DFS_2016 | Distribution.SPDX.LicenseId, Distribution.SPDX | 
| Unicode_TOU | Distribution.SPDX.LicenseId, Distribution.SPDX | 
| unintersperse | Distribution.Utils.Generic | 
| unionLeft | Distribution.Compat.Graph | 
| unionRight | Distribution.Compat.Graph | 
| unionVersionIntervals | Distribution.Types.VersionInterval.Legacy | 
| UnionVersionRanges | Distribution.Types.VersionRange.Internal | 
| unionVersionRanges | Distribution.Types.VersionRange.Internal, Distribution.Types.VersionRange, Distribution.Version | 
| UnionVersionRangesF | Distribution.Types.VersionRange.Internal, Distribution.Types.VersionRange, Distribution.Version | 
| uniqueField | Distribution.FieldGrammar.Class, Distribution.FieldGrammar | 
| uniqueFieldAla | Distribution.FieldGrammar.Class, Distribution.FieldGrammar | 
| UnitId | Distribution.Types.UnitId, Distribution.Package | 
| Universal_FOSS_exception_1_0 | Distribution.SPDX.LicenseExceptionId, Distribution.SPDX | 
| unknownCompilerInfo | Distribution.Compiler | 
| UnknownExtension | Language.Haskell.Extension | 
| UnknownLanguage | Language.Haskell.Extension | 
| UnknownLicense | Distribution.License | 
| unless | Distribution.Compat.Prelude | 
| unLex | Distribution.Fields.LexerMonad | 
| Unlicense | Distribution.SPDX.LicenseId, Distribution.SPDX | 
| UnliftedDatatypes | Language.Haskell.Extension | 
| UnliftedFFITypes | Language.Haskell.Extension | 
| UnliftedNewtypes | Language.Haskell.Extension | 
| unlines | Distribution.Compat.Prelude | 
| unpack | Distribution.Compat.Newtype | 
| unpack' | Distribution.Compat.Newtype | 
| unPackageName | Distribution.Types.PackageName, Distribution.Package, Distribution.PackageDescription | 
| unPackageNameST | Distribution.Types.PackageName, Distribution.Package, Distribution.PackageDescription | 
| unPkgconfigName | Distribution.Types.PkgconfigName, Distribution.Package, Distribution.PackageDescription | 
| unPP | Distribution.Parsec | 
| UnqualComponentName | Distribution.Types.UnqualComponentName, Distribution.PackageDescription | 
| unqualComponentNameToPackageName | Distribution.Types.UnqualComponentName, Distribution.PackageDescription | 
| Unsafe | Language.Haskell.Extension | 
| unsafeFromUTF8BS | Distribution.Utils.ShortText | 
| unsafeMakeSymbolicPath | Distribution.Utils.Path | 
| unsafeMkDefUnitId | Distribution.Types.UnitId, Distribution.Package | 
| unsnoc | Distribution.Utils.Generic | 
| unsnocNE | Distribution.Utils.Generic | 
| UnspecifiedLicense | Distribution.License | 
| until | Distribution.Compat.Prelude | 
| unUnitId | Distribution.Types.UnitId, Distribution.Package | 
| unUnqualComponentName | Distribution.Types.UnqualComponentName, Distribution.PackageDescription | 
| unUnqualComponentNameST | Distribution.Types.UnqualComponentName, Distribution.PackageDescription | 
| unvalidateBenchmark | Distribution.PackageDescription.FieldGrammar | 
| unvalidateTestSuite | Distribution.PackageDescription.FieldGrammar | 
| unVersionIntervals | Distribution.Types.VersionInterval, Distribution.Version | 
| unwords | Distribution.Compat.Prelude | 
| unzip | Distribution.Compat.Prelude | 
| unzip3 | Distribution.Compat.Prelude | 
| updatePackageDescription | Distribution.Types.PackageDescription, Distribution.PackageDescription | 
| UPL_1_0 | Distribution.SPDX.LicenseId, Distribution.SPDX | 
| upper | Distribution.Compat.CharParsing | 
| UpperBound |  | 
| 1 (Type/Class) | Distribution.Types.VersionInterval.Legacy | 
| 2 (Data Constructor) | Distribution.Types.VersionInterval.Legacy | 
| 3 (Type/Class) | Distribution.Types.VersionInterval, Distribution.Version | 
| 4 (Data Constructor) | Distribution.Types.VersionInterval, Distribution.Version | 
| use | Distribution.Compat.Lens | 
| usedExtensions | Distribution.Types.BuildInfo, Distribution.PackageDescription | 
| userBug | Distribution.PackageDescription.Utils | 
| userError | Distribution.Compat.Prelude | 
| usesTemplateHaskellOrQQ | Distribution.Types.BuildInfo, Distribution.PackageDescription | 
| U_boot_exception_2_0 | Distribution.SPDX.LicenseExceptionId, Distribution.SPDX |