| UnableResolveQualified | Fay.Types.CompileError, Fay.Types, Fay |
| unCompile | Fay.Types |
| uncons | Fay.Compiler.Prelude |
| uncurry | Fay.Compiler.Prelude |
| Undefined | Fay.FFI |
| undefined | Fay.Compiler.Prelude |
| unfoldr | Fay.Compiler.Prelude |
| union | Fay.Compiler.Prelude |
| unionBy | Fay.Compiler.Prelude |
| UnknownType | Fay.Types |
| unless | Fay.Compiler.Prelude |
| unlines | Fay.Compiler.Prelude |
| unModulePath | Fay.Types |
| UnsupportedDeclaration | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedEnum | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedExportSpec | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedExpression | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedFieldPattern | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedImport | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedLet | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedLetBinding | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedLiteral | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedModuleSyntax | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedPattern | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedQualStmt | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedRecursiveDo | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedRhs | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedWhereInAlt | Fay.Types.CompileError, Fay.Types, Fay |
| UnsupportedWhereInMatch | Fay.Types.CompileError, Fay.Types, Fay |
| until | Fay.Compiler.Prelude |
| unwords | Fay.Compiler.Prelude |
| unwrapArrow | Fay.Compiler.Prelude |
| unwrapMonad | Fay.Compiler.Prelude |
| unzip | Fay.Compiler.Prelude |
| unzip3 | Fay.Compiler.Prelude |
| unzip4 | Fay.Compiler.Prelude |
| unzip5 | Fay.Compiler.Prelude |
| unzip6 | Fay.Compiler.Prelude |
| unzip7 | Fay.Compiler.Prelude |
| UserDefined | Fay.Types |
| userError | Fay.Compiler.Prelude |