[Haskell-cafe] containers-deepseq?

Michael Snoyman michael at snoyman.com
Tue Nov 29 06:45:06 CET 2011

On Tue, Nov 29, 2011 at 7:43 AM, Michael Snoyman <michael at snoyman.com> wrote:
> Hi all,
> Since the release of deepseq 1.2, we've had a bit of a problem: when
> using the newest versions of packages on Hackage, there is no NFData
> instance available for the containers types. When GHC 7.4 comes out
> with its newer version of containers, this will be addressed, but
> we'll still have problems for users of older GHC releases.
> I'd like to suggest a solution: a new package called
> containers-deepseq. Using conditional compilation, it will provide an
> orphans NFData instance for all containers types when deepseq >= 1.2
> and containers < 0.5. Packages (e.g., aeson) would then depend on
> containers-deepseq and simply import the module whenever they rely on
> the NFData instances. When GHC 7.4 comes out, the package will
> essentially be a no-op.
> Does this make sense?
> Michael

Sorry, that should be containers < 0.4.2.


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