5 | | * [http://www.haskell.org/ghc/dist/current/docs/~~html/~~libraries/base/Data-Typeable.html Data.Typeable] |

6 | | * [http://www.haskell.org/ghc/dist/current/docs/~~html/~~libraries/base/Data-Dynamic.html Data.Dynamic] |

7 | | * [http://www.haskell.org/ghc/dist/current/docs/~~html/~~libraries/base/Control-Monad-Fix.html Control.Monad.Fix] (for the IO instance) |

8 | | * [http://www.haskell.org/ghc/dist/current/docs/~~html/~~libraries/base/Data-IORef.html Data.IORef] |

9 | | * [http://www.haskell.org/ghc/dist/current/docs/~~html/~~libraries/base/Control-Monad-ST.html Control.Monad.ST] (requires [wiki:Rank2Types]) |

| 5 | * [http://www.haskell.org/ghc/dist/current/docs/libraries/base/Data-Typeable.html Data.Typeable] |

| 6 | * [http://www.haskell.org/ghc/dist/current/docs/libraries/base/Data-Dynamic.html Data.Dynamic] |

| 7 | * [http://www.haskell.org/ghc/dist/current/docs/libraries/base/Control-Monad-Fix.html Control.Monad.Fix] (for the IO instance) |

| 8 | * [http://www.haskell.org/ghc/dist/current/docs/libraries/base/Data-IORef.html Data.IORef] |

| 9 | * [http://www.haskell.org/ghc/dist/current/docs/libraries/base/Control-Monad-ST.html Control.Monad.ST] (requires [wiki:Rank2Types]) |