[GHC] #9707: (Try to) restructure `base` to allow more use of `AutoDeriveTypeable`

[GHC]

#9707: (Try to) restructure `base` to allow more use of `AutoDeriveTypeable`
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              Reporter:  hvr         |            Owner:  ekmett
                  Type:  task        |           Status:  new
              Priority:  normal      |        Milestone:  7.12.1
             Component:  Core        |          Version:
  Libraries                          |         Keywords:  Typeable
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Difficult (2-5
  Unknown/Multiple                   |  days)
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:  #9111
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Description changed by hvr:

Old description:

> comment:ticket:9111:16 explains that import-cycles containing
> `Data.Typeable.Internal` (which provides the `Typeable` class
> `AutoDeriveTypeable` needs to be loaded for being able to operate) inside
> `base` make it difficult  to use `AutoDeriveTypeable`, as well as making
> it more difficult to de-cycle the `base` import-dependency graph (see
> also attachment:typeable_deps.pngtypeable_deps.png)
>
> This ticket is about trying to find a way to restructure `base` in order
> to allow to define the `Typeable` instances directly at the type's
> defining site (and thus allow the use of `AutoDeriveTypeable`)

New description:

 comment:ticket:9111:16 explains that import-cycles containing
 `Data.Typeable.Internal` (which provides the `Typeable` class
 `AutoDeriveTypeable` needs to be loaded for being able to operate) inside
 `base` make it difficult  to use `AutoDeriveTypeable`, as well as making
 it more difficult to de-cycle the `base` import-dependency graph (see also
 attachment:typeable_deps.png)

 This ticket is about trying to find a way to restructure `base` in order
 to allow to define the `Typeable` instances directly at the type's
 definition site (and thus allow the use of `AutoDeriveTypeable`)

 Removing cycles in `base` is possibly required to make SplitBase easier

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9707#comment:2>
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