[GHC] #10048: {-# UNPACK #-} support for size-indexed types

[GHC]

#10048: {-# UNPACK #-} support for size-indexed types
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        Reporter:  dfeuer            |                   Owner:
            Type:  feature request   |                  Status:  closed
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:  invalid           |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Changes (by dfeuer):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 Replying to [comment:1 rwbarton]:
 > How would we implement
 >
 > {{{
 > hlength :: HList l -> Int
 > hlength Nil = 0
 > hlength (Cons _ xs) = 1 + hlength xs
 > }}}
 >
 > then? (Bear in mind that we have no access to the type parameter `l` at
 runtime.)
 >
 > I think this sort of thing could only work with a type family rather
 than a GADT (and even then I haven't thought about whether it actually
 could work).

 Ah, you make a very good point.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10048#comment:2>
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