[GHC] #14770: Allow static pointer expressions to have static pointer free variables

[GHC]

#14770: Allow static pointer expressions to have static pointer free variables
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        Reporter:  TheKing01         |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:
                                     |  StaticPointers
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 gershomb):

 No concrete use-case at the moment (in that I'm not working on a system
 that does cloud distribution). I wanted to track this ticket as I've been
 thinking a lot about questions related to this ticket, including possible
 other uses for `static` and how it relates to Contextual Modal Type Theory
 (and also the question of staging).

 I think the ticket has the right of it in terms of the problem.
 Semantically, the "correct" thing to do is, treating `StaticPtr` as a
 modality, allow computation _within_ the modality such that we have
 `StaticPtr (a -> b) -> StaticPtr a -> StaticPtr b` directly. Instead, we
 have the workaround the ticket points to, which makes use of an opaque
 GADT. So that means, as the ticket says, this gives (on its own) a
 potential efficiency gain, but not expressivity gain.

 I think we'll need more people using static pointers "at scale" to see if
 the efficiency cost becomes a genuine pain point.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14770#comment:5>
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