| Rank2Types | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| RankNTypes | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| RebindableSyntax | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| RecordPuns | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| RecordWildCards | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| RecursiveDo | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| RegularPatterns | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| RelaxedPolyRec | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| reset | Language.Haskell.Interpreter |
| RestrictedTypeSynonyms | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| RoleAnnotations | Language.Haskell.Interpreter.Extension, Language.Haskell.Interpreter |
| runGhc | Language.Haskell.Interpreter |
| runInterpreter | Language.Haskell.Interpreter |