[GHC] #1338: base package breakup

[GHC]

#1338: base package breakup
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    Reporter:  simonmar          |        Owner:                  
        Type:  task              |       Status:  new             
    Priority:  normal            |    Milestone:  6.12 branch     
   Component:  libraries/base    |      Version:  6.6.1           
    Severity:  normal            |   Resolution:                  
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:                    |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
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Comment (by mokus):

 Would it be possible to implement at least as much of this splitting as is
 needed to remove all "unsafe" operations from base?  I would very much
 like to be able to use packages as a 'unit of analysis' for a relatively
 simple library I'm working on that attempts to maintain a package database
 of "safe" packages (verified not to perform any "dangerous" IO outside the
 IO type, for example).

 Unfortunately, as it stands now the analysis is polluted from the start
 due to base's inclusion of unsafePerformIO, unsafeCoerce, unsafeSTToIO,
 the ability to define custom Typeable instances, large parts of the whole
 GHC subtree, and possibly other surprises.  If these could be removed from
 base, it would make things much simpler.  At present I am using a "base-
 safe" wrapper that uses the PackageImports extension (thanks for that by
 the way, it's great!) to export a subset of the base library, but it would
 be much cleaner to have base itself be "pure" so that all cabal packages
 using it (and build-type Simple and only "safe" language extensions) could
 be automatically ruled "pure" as well.

 Plus, doesn't it just give you lots of warm fuzzies to think of Haskell's
 base library as pure?  Or to put it differently, doesn't it just give you
 the screaming heebie-jeebies that unsafePerformIO is in base at all? ;)

 If proliferation of small packages is a concern, perhaps the split could
 be implemented by renaming the existing base to, say, "base-unsafe", and
 providing smaller interface wrapper packages using PackageImports as,
 e.g., base, st, unsafe-io, unsafe-st, foreign, and so on.  I don't know
 whether that actually solves whatever the concern is over small packages,
 but it would at least allow the interface to be broken up without
 requiring as much effort as a full disentanglement of all the module
 dependencies.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1338#comment:29>
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