[GHC] #10681: Teach GHC to interpret all hs files as two levels of hs-boot files (abstract types only/full types + values)

[GHC]

#10681: Teach GHC to interpret all hs files as two levels of hs-boot files
(abstract types only/full types + values)
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        Reporter:  ezyang            |                   Owner:  ezyang
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by goldfire):

 ezyang says:

 > This seems to definitely suggest that you should never need more than
 two levels of hs-boot nesting, or perhaps three with kinding. (But maybe
 someone has a fancy type system feature for which this is not true!)

 I believe I have such a fancy type system feature. My solution to #7961
 (that is, my very long-running "nokinds"
 [https://github.com/goldfirere/ghc/ branch], due to be merged Any Season
 Now [at least it's better than Any Year Now]) merges types with kinds,
 allowing an arbitrary number of "levels". In other words, I think a
 pathological case can (if I understand your proposal here correctly)
 require an arbitrary number of hs-boot levels.

 For example:

 {{{
 data A
 data B :: A -> *
 data C :: B a -> *
 data D :: C b -> *
 data E :: D c -> *
 }}}

 This compiles fine on my branch, but I believe would cause problems with
 this proposal.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10681#comment:3>
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