[GHC] #7016: Declarations after top-level splice are ignored

[GHC]

#7016: Declarations after top-level splice are ignored
---------------------------------------+------------------------------------
 Reporter:  Oblosys                    |          Owner:                  
     Type:  bug                        |         Status:  new            
 Priority:  normal                     |      Component:  Template Haskell
  Version:  7.4.2                      |       Keywords:                  
       Os:  MacOS X                    |   Architecture:  x86_64 (amd64)  
  Failure:  GHC rejects valid program  |       Testcase:                  
Blockedby:                             |       Blocking:                  
  Related:                             |  
---------------------------------------+------------------------------------
 Declarations that appear after a top-level splice seem to be ignored
 without any warning. In the attached Main, the identifier afterSplice is
 not recognized:

 {{{
 Main.hs:6:11: Not in scope: `afterSplice'
 }}}

 The error disappears if the declaration of afterSplice is put before
 dummySplice, or if the declaration for problem is removed (in which case
 afterSplice is declared correctly, as can be seen with in ghci.)

 I could track the problem back to at least ghc-7.0.4.

--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7016>
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[GHC]

#7016: Declarations after top-level splice are ignored
----------------------------------------+-----------------------------------
  Reporter:  Oblosys                    |          Owner:                
      Type:  bug                        |         Status:  closed        
  Priority:  normal                     |      Milestone:                
 Component:  Template Haskell           |        Version:  7.4.2        
Resolution:  invalid                    |       Keywords:                
        Os:  MacOS X                    |   Architecture:  x86_64 (amd64)
   Failure:  GHC rejects valid program  |     Difficulty:  Unknown      
  Testcase:                             |      Blockedby:                
  Blocking:                             |        Related:                
----------------------------------------+-----------------------------------
Changes (by simonpj):

  * status:  new => closed
  * difficulty:  => Unknown
  * resolution:  => invalid


Comment:

 This is by design, as described in Section 7.2 of the original
 [http://research.microsoft.com/en-us/um/people/simonpj/papers/meta-haskell
 /meta-haskell.pdf Template Haskell paper].

 I agree it's not ideal, but it's not accidental, and I don't know of a
 better way.

 Hmm.  It may be that some of the changes mooted in my
 [http://hackage.haskell.org/trac/ghc/blog/Template%20Haskell%20Proposal
 New directions for Template Haskell] post (which I plan to work in on
 August) may change this.

 Simon

--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7016#comment:1>
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[GHC]

#7016: Declarations after top-level splice are ignored
----------------------------------------+-----------------------------------
  Reporter:  Oblosys                    |          Owner:                
      Type:  bug                        |         Status:  closed        
  Priority:  normal                     |      Milestone:                
 Component:  Template Haskell           |        Version:  7.4.2        
Resolution:  invalid                    |       Keywords:                
        Os:  MacOS X                    |   Architecture:  x86_64 (amd64)
   Failure:  GHC rejects valid program  |     Difficulty:  Unknown      
  Testcase:                             |      Blockedby:                
  Blocking:                             |        Related:                
----------------------------------------+-----------------------------------

Comment(by Oblosys):

 Ah, so it's a feature! :-) Perhaps this could be briefly mentioned in the
 documentation? (right after the quieter and less intimidating example). I
 thought it was a bug because I couldn't find it there and the error
 message didn't mention Template Haskell.

 It's just a small issue, but since I use TH to derive type classes for
 data declarations, the most appropriate place for the splice would be
 close to the data declaration. (Each data type is also accompanied by a
 function declaration, which causes the scoping issues.)

 I will await the changes from the new directions post!

 -- Martijn

--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7016#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler

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