[GHC] #16240: Core visible conditional compilation/static definition/code selection based upon static key values

[GHC]

#16240: Core visible  conditional compilation/static definition/code selection
based upon static key values
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        Reporter:  carter            |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.7
      Resolution:                    |             Keywords:
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 alanz):

 I think we should consider separately the operation of conditionals to
 enable/disable/switch out blocks of code, and the use of other (CPP)
 primitives such as `#define` as a shortcut for configuring code.

 I regard the former as "low-power" and potentially able to be manageable
 integrated into tooling, if we assume that the inactive block must meet
 some minimal syntactic requirements, but not necessarily be able to be
 fully parsed or type checked.

 The latter should be discouraged, and if needed fall back to CPP as we
 have now, with the understanding that certain classed of tooling are then
 not possible.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16240#comment:5>
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