Modules and their explicit export lists (are an annoyance)

Christian Höner zu Siederdissen choener at
Mon Jun 21 17:20:30 EDT 2010

Thanks everybody for your thoughts. Based on what I've read this is what
I will do:

- fork a 'foreign' library, if I need to extend it substantially
- export everything explicitly
- or set namespaces like this:
  - Library (with the more stable interface)
  - Library.Internal (which exports everything)

Because of the rather good versioning system of Cabal (like
library=x.y.z) this seems to be the most practical solution for me.

Though it still would be nice if I could inject functions into other
peoples' namespaces -- so to speak ;-)


* Christian Höner zu Siederdissen <choener at> [19.06.2010 20:39]:
> Hi everybody,
> I'd like some input on other peoples' thoughts on this. Recently, I
> played around with a library that uses an explicit export list. While
> there are reasons for having one:
> - efficiencey (inlining in the module)
> - encapsulation
> in practice, it seems to me that they are more annoying than useful. For
> once, it would think that ghc should produce efficient good across
> modules with -O / -O2 anyway.
> But the more important thing is, that it makes extending module
> functionality a pain (eg. if a constructor is not exported using (..)).
> So, should I really fork a library just to be able to add a function?
> Btw. there are libraries, where an explicit export list is used, that
> export the right amount of information. For example, in 'vector' enough
> is exported to allow you to extend unboxed vectors.

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> Glasgow-haskell-users mailing list
> Glasgow-haskell-users at

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