[GHC] #1475: Adding imports and exports with Template Haskell

[GHC]

#1475: Adding imports and exports with Template Haskell
-------------------------------+--------------------------------------------
  Reporter:  igloo             |          Owner:         
      Type:  feature request   |         Status:  new    
  Priority:  normal            |      Milestone:  6.8    
 Component:  Template Haskell  |        Version:  6.6.1  
  Severity:  normal            |       Keywords:         
Difficulty:  Unknown           |             Os:  Unknown
  Testcase:                    |   Architecture:  Unknown
-------------------------------+--------------------------------------------
(wished for by Adrian Hey in http://www.haskell.org/pipermail/template-
 haskell/2007-June/000598.html)

 It would be useful to be able to add module exports with TH, although I'm
 not sure exactly how it would be done. Perhaps something like
 {{{
 $( do n <- newName "foo"
       let d = funD n ...
       addExport (varE n)
       return [d]
 }}}
 but at the point we call `addExport` the typechecker doesn't know that
 there will be a declaration for the name.

 Less useful, as TH names include the package and module of the name's
 definition, is the ability to add module imports. However, this can still
 be used to get a kind of dynamic binding effect, either with `mkName`'s
 names or plain Haskell code, e.g.:
 {{{
 $( addImport (if ... then '''Data.ByteString else '''Data.ByteString.Lazy)
              (mkName "BS") )

 foo :: BS.ByteString
 foo = BS.append ...
 }}}
 (we'd actually probably want a datatype that mirrors Haskell import decls
 more closely).

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1475>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
-------------- next part --------------
_______________________________________________
Glasgow-haskell-bugs mailing list
Glasgow-haskell-bugs at haskell.org
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs