[GHC] #4443: Don't require users to use undefined

[GHC]

#4443: Don't require users to use undefined
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  Reporter:  basvandijk      |          Owner:                  
      Type:  proposal        |         Status:  closed          
  Priority:  normal          |      Milestone:  Not GHC         
 Component:  libraries/base  |        Version:  6.12.3          
Resolution:  wontfix         |       Keywords:                  
  Testcase:                  |      Blockedby:                  
Difficulty:                  |             Os:  Unknown/Multiple
  Blocking:                  |   Architecture:  Unknown/Multiple
   Failure:  None/Unknown    |  
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Changes (by basvandijk):

  * status:  new => closed
  * resolution:  => wontfix


Comment:

 I'm closing this ticket as 'wontfix' because most people objected to this
 proposal. The main reason was: lots of code will break while there's
 little benefit.

 Henning Thielemann proposed an interesting compromise:

 Since all of the affected modules are quite basic, this would break a lot
 of code. Thus I would propose a less invasive path:

 1. Add functions that provide the Tagged interface and implement them
 using 'sizeOf' and 'alignment'.

 2. Add functions that convert a sizeOfTagged and alignmentTagged function
 to 'sizeOf' and 'alignment' in order to allow Storable instance
 declaration, that not need to cope with undefined.

 3. Document how to use the Tagged types with Haskell 98.

 4. In the future you may deprecate the immediate use of 'sizeOf' and
 'alignment'.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4443#comment:3>
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