Shared data type for extension flags

[Michael Smith]

The package description for that is "The GHC compiler's view of the GHC
package database format", and this doesn't really have to do with the
package database format. Would it be okay to put this in there anyway?

On Wed, Sep 2, 2015, 07:33 Simon Peyton Jones <simonpj at microsoft.com> wrote:

> we already have such a shared library, I think: bin-package-db.  would
> that do?
>
>
>
> Simon
>
>
>
> *From:* ghc-devs [mailto:ghc-devs-bounces at haskell.org] *On Behalf Of *Michael
> Smith
> *Sent:* 02 September 2015 09:21
> *To:* Matthew Pickering
> *Cc:* GHC developers
> *Subject:* Re: Shared data type for extension flags
>
>
>
> That sounds like a good approach. Are there other things that would go
> nicely
> in a shared package like this, in addition to the extension data type?
>
>
>
> On Wed, Sep 2, 2015 at 1:00 AM, Matthew Pickering <
> matthewtpickering at gmail.com> wrote:
>
> Surely the easiest way here (including for other tooling - ie
> haskell-src-exts) is to create a package which just provides this
> enumeration. GHC, cabal, th, haskell-src-exts and so on then all
> depend on this package rather than creating their own enumeration.
>
>
> On Wed, Sep 2, 2015 at 9:47 AM, Michael Smith <michael at diglumi.com> wrote:
> > #10820 on Trac [1] and D1200 on Phabricator [2] discuss adding the
> > capababilty
> > to Template Haskell to detect which language extensions enabled.
> > Unfortunately,
> > since template-haskell can't depend on ghc (as ghc depends on
> > template-haskell),
> > it can't simply re-export the ExtensionFlag type from DynFlags to the
> user.
> >
> > There is a second data type encoding the list of possible language
> > extensions in
> > the Cabal package, in Language.Haskell.Extension [3]. But
> template-haskell
> > doesn't already depend on Cabal, and doing so seems like it would cause
> > difficulties, as the two packages can be upgraded separately.
> >
> > So adding this new feature to Template Haskell requires introducing a
> > *third*
> > data type for language extensions. It also requires enumerating this full
> > list
> > in two more places, to convert back and forth between the TH Extension
> data
> > type
> > and GHC's internal ExtensionFlag data type.
> >
> > Is there another way here? Can there be one single shared data type for
> this
> > somehow?
> >
> > [1] https://ghc.haskell.org/trac/ghc/ticket/10820
> > [2] https://phabricator.haskell.org/D1200
> > [3]
> >
> https://hackage.haskell.org/package/Cabal-1.22.4.0/docs/Language-Haskell-Extension.html
> >
>
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> >
>
>
>
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