[GHC] #13639: Skylighting package compilation is glacial

[GHC]

#13639: Skylighting package compilation is glacial
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        Reporter:  bgamari           |                Owner:  dfeuer
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by dfeuer):

 * cc: mpickering (added)


Comment:

 I'm just getting back to looking at this. Since we don't have a record of
 the problematic `skylighting` version, let's go with the guess that this
 is the issue reported as [https://github.com/jgm/skylighting/issues/7
 skylighting issue #7]. That is, that `skylighting-0.1.1.5` compiles
 slowly. There is further discussion of the problem in
 [https://github.com/jgm/texmath/issues/96 texmath issue #96]. mpickering
 was involved in those discussions; I don't know how much he
 knows/remembers.

 Their conclusion was that very large static data can take a long time to
 compile, for some reason. This whole thing sounds very familiar somehow;
 wasn't there some recentish work on handling ticks better for long list
 literals or some such?

 The package worked around this problem in
 [https://github.com/jgm/skylighting/commit/851bdd1e210ddecb00ceeffcabd9bf1fdc17b60e
 Skylighting.Syntax.*: use string representation of the Syntax] which
 simply used `read` to read a `String` representation of the data. Later,
 they
 [https://github.com/jgm/skylighting/commit/90ae0d0c23b7f8b218ff01152a912e374245aa5a
 switched to Binary].

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13639#comment:3>
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