[GHC] #1409: Allow recursively dependent modules transparently (without .hs-boot or anything)

[GHC]

#1409: Allow recursively dependent modules transparently (without .hs-boot or
anything)
---------------------------------+------------------------------------------
    Reporter:  Isaac Dupree      |       Owner:                  
        Type:  feature request   |      Status:  new             
    Priority:  normal            |   Milestone:  _|_             
   Component:  Compiler          |     Version:  6.10.2          
    Keywords:                    |          Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |     Failure:  None/Unknown    
  Difficulty:  Unknown           |    Testcase:                  
   Blockedby:                    |    Blocking:                  
     Related:                    |  
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Comment(by singpolyma):

 I'm strongly considering using CPP and #include to work around this
 problem in my most recent project.

 The problem I have is both the duplication of information in two places
 (very un-DRY) and having to pick a place to break the import cycle.  I
 understand that doing this cross-package (if that even ever makes sense at
 all) would be very complex, but I think what most people here (correct me
 if I'm wrong) are interested in is the case where all the source for all
 the modules is in one project and thus can be build with a single GHC
 invocation.

 Since pasting the contents of one module into the top of another instead
 of importing it works (hence my thoughts about CPP and #include) the way
 forward seems to be: treat all modules in a cycle as a single module with
 multiple names/export lists.  That way the compiler has no problem (since
 it can compile all these as one module already, if I paste all the code
 together) and imports of any of the modules into *other* modules would
 still work (since GHC would just pick which things to import/can be
 imported from the mega-module based on which of its names was used).

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1409#comment:53>
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