[GHC] #13498: More storable instances?

[GHC]

#13498: More storable instances?
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        Reporter:  wyager            |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  libraries/base    |              Version:  8.0.1
      Resolution:                    |             Keywords:  Storable,
                                     |  Foreign, Ptr
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by svenpanne):

 The reasoning why sum types have no `Storable` instance by default is that
 the encoding would be quite arbitrary. In your example: Why are the tags 8
 bit wide, and why are the tag values `0` and `1`? Do we need a tag at all?
 For e.g. `Maybe (Ptr a)` a more common encoding is to have no tag at all
 and represent `Nothing` as a null pointer. For product types things are
 less arbitrary, but even then there is the issue of alignment. If you need
 serialization, you can use `Data.Binary`.

 I think we should close this ticket as `wontfix`, because the lack of
 these instances was a very deliberate decision.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13498#comment:1>
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