If I understand this correctly it would also subsume haskell-src-exts. If so I would definitely support this. On Nov 11, 2015 2:21 PM, "Edward Kmett" <ekm...@gmail.com> wrote:
> In practice I find that almost every piece of template-haskell code I've > written gets broken by something every other release of GHC, so it hasn't > exactly been a shining beacon of backwards compatibility thus far. > > Invariably it is always missing _something_ that I need, and anything that > ties it to a more canonical form like this would be a very good thing. > > I'd strongly support this move. > > A sample just from my current working directory: > > haskell> grep -r MIN_VERSION_template_haskell */src > > bifunctors/src/Data/Bifunctor/TH/Internal.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > bifunctors/src/Data/Bifunctor/TH/Internal.hs:#if > MIN_VERSION_template_haskell(2,7,0) > > bifunctors/src/Data/Bifunctor/TH/Internal.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > bifunctors/src/Data/Bifunctor/TH/Internal.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > bifunctors/src/Data/Bifunctor/TH/Internal.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > bifunctors/src/Data/Bifunctor/TH/Internal.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > bifunctors/src/Data/Bifunctor/TH.hs:#ifndef MIN_VERSION_template_haskell > > bifunctors/src/Data/Bifunctor/TH.hs:#if __GLASGOW_HASKELL__ < 710 && > MIN_VERSION_template_haskell(2,8,0) > > bifunctors/src/Data/Bifunctor/TH.hs:#if MIN_VERSION_template_haskell(2,7,0) > > bifunctors/src/Data/Bifunctor/TH.hs:#if MIN_VERSION_template_haskell(2,7,0) > > bifunctors/src/Data/Bifunctor/TH.hs:#if MIN_VERSION_template_haskell(2,7,0) > > bifunctors/src/Data/Bifunctor/TH.hs:#if MIN_VERSION_template_haskell(2,7,0) > > bifunctors/src/Data/Bifunctor/TH.hs:#if MIN_VERSION_template_haskell(2,7,0) > > bifunctors/src/Data/Bifunctor/TH.hs:# if __GLASGOW_HASKELL__ >= 710 || > !(MIN_VERSION_template_haskell(2,8,0)) > > bifunctors/src/Data/Bifunctor/TH.hs:#if MIN_VERSION_template_haskell(2,7,0) > > free/src/Control/Monad/Free/TH.hs:#if MIN_VERSION_template_haskell(2,10,0) > > lens/src/Control/Lens/Internal/FieldTH.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Control/Lens/Internal/TH.hs:#ifndef MIN_VERSION_template_haskell > > lens/src/Control/Lens/Internal/TH.hs:#define > MIN_VERSION_template_haskell(x,y,z) (defined(__GLASGOW_HASKELL__) && > __GLASGOW_HASKELL__ >= 706) > > lens/src/Control/Lens/Internal/TH.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Control/Lens/Plated.hs:#if !(MIN_VERSION_template_haskell(2,8,0)) > > lens/src/Control/Lens/TH.hs:#ifndef MIN_VERSION_template_haskell > > lens/src/Control/Lens/TH.hs:#define MIN_VERSION_template_haskell(x,y,z) > (defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ >= 706) > > lens/src/Control/Lens/TH.hs:#if !(MIN_VERSION_template_haskell(2,7,0)) > > lens/src/Control/Lens/TH.hs:#if MIN_VERSION_template_haskell(2,10,0) > > lens/src/Control/Lens/TH.hs:#if !(MIN_VERSION_template_haskell(2,7,0)) > > lens/src/Language/Haskell/TH/Lens.hs:#ifndef MIN_VERSION_template_haskell > > lens/src/Language/Haskell/TH/Lens.hs:#define > MIN_VERSION_template_haskell(x,y,z) 1 > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > !MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > !MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > !MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,8,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > !MIN_VERSION_template_haskell(2,10,0) > > lens/src/Language/Haskell/TH/Lens.hs:#if > MIN_VERSION_template_haskell(2,9,0) > > linear/src/Linear/V.hs:#ifdef MIN_VERSION_template_haskell > > linear/src/Linear/V.hs:#if !(MIN_VERSION_reflection(1,3,0)) && > defined(MIN_VERSION_template_haskell) > > linear/src/Linear/V.hs:#if !(MIN_VERSION_reflection(1,3,0)) && > defined(MIN_VERSION_template_haskell) > > nats/src/Numeric/Natural.hs:#if defined(MIN_VERSION_hashable) || > defined(MIN_VERSION_template_haskell) > > nats/src/Numeric/Natural.hs:#ifdef MIN_VERSION_template_haskell > > nats/src/Numeric/Natural.hs:#ifdef MIN_VERSION_template_haskell > > tables/src/Data/Table.hs:#if MIN_VERSION_template_haskell(2,10,0) > > tables/src/Data/Table.hs:#if MIN_VERSION_template_haskell(2,9,0) > > tagged/src/Data/Proxy/TH.hs:#if MIN_VERSION_template_haskell(2,8,0) > > tagged/src/Data/Proxy/TH.hs:#if MIN_VERSION_template_haskell(2,8,0) > > tagged/src/Data/Proxy/TH.hs:#if MIN_VERSION_template_haskell(2,8,0) > > tagged/src/Data/Proxy/TH.hs:#if MIN_VERSION_template_haskell(2,8,0) > > On Wed, Nov 11, 2015 at 12:46 PM, Eric Seidel <e...@seidel.io> wrote: > >> I think backwards-compatibility is still a potential issue, not because >> the pattern/type synonym layer seems implausible, but because I suspect >> people will begin to sidestep the compatibility layer and just use the >> GHC API (I certainly would). GHC is not shy about breaking >> backwards-compatibility between major releases, so it seems possible >> that this could extend to breaking TH. Missing features is not nearly as >> bad as breaking most clients of TH. >> >> But perhaps this isn't a very likely scenario. TH mostly exports >> datatypes for haskell syntax, smart constructors, and a few functions >> for looking up metadata. I doubt these pieces of GHC change very often, >> and when they do it's probably an extension rather than a breaking >> change. Someone with more historical knowledge of GHC could comment :) >> >> All in all, I like this idea a lot! >> >> Eric >> >> On Wed, Nov 11, 2015, at 08:26, Richard Eisenberg wrote: >> > Hi devs, >> > >> > There's a bunch of open tickets around Template Haskell. A great many of >> > them are attempts to make TH more like what's already in GHC. Of course, >> > when someone improves GHC, then TH also has to be updated. But this >> > doesn't always happen, leading to several of these tickets. >> > >> > I believe I have a solution to the problem: just eliminate Template >> > Haskell and provide direct access to GHC's internal structures. The idea >> > (still very sketchy; hence pre-proposal) is like this (numbered for easy >> > reference, but no order is implied): >> > >> > 1. TH quotes would remain. DsMeta would desugar quotes into Core code >> > that produces HsExprs. For example, [| 1 |] would have type (Q (LHsExpr >> > Name)). (Or perhaps (Q (LHsExpr RdrName)) if that works out better for >> > clients.) >> > >> > 2. TH splices would remain, working much as they do now. The expression >> > inside, say, an expression splice would have type (Q exp) where we can >> > satisfy the constraint (SpliceExpr exp). There would be instances for >> > (SpliceExpr (LHsExpr Name)) and (SpliceExpr (LHsExpr RdrName)) as well >> as >> > the non-located variants. Generalizing the type of expressions here >> > allows users not to worry about un-renaming when roundtripping between >> > quotes and splices. >> > >> > 3. Reification would remain, using an Info structure much like we have >> > now. Would we expose the real GHC TyCons as the result of reification? >> Or >> > is it better to give the users HsDecls? This would need to be fleshed >> > out. >> > >> > 4. Lifting would remain, doing the obvious thing. >> > >> > 5. The template-haskell package could even remain, as a >> > backward-compatibility shim. It would declare gobs of pattern synonyms >> > and type synonyms to wrap the new underlying interface. This re-imagined >> > template-haskell package would not need to be a boot library, and could >> > be upgraded separately from GHC. We could even maintain multiple >> versions >> > of the library so that TH clients wouldn't have to change their code >> when >> > GHC upgrades. Perhaps someday we could think about deprecating, if >> that's >> > the way the wind blows. >> > >> > So, the end result is a completely re-engineered TH, but I believe we >> > could keep full backward compatibility. (I have not considered Typed TH >> > in any depth yet. But my hope is that it's not too different from the >> > above.) And, we're left with a significantly lower maintenance burden, >> > especially if we eliminate template-haskell someday. >> > >> > And, tantalizingly, the flexibility in splices might allow us to splice >> > in *Core* code someday. Perhaps we could also reify Core code. Then >> > clients could write their own custom, domain-aware optimizations. Like >> > RULES on steroids. But that's all for the next phase. (Giving due >> credit, >> > this last bit is inspired by work David Christiansen is doing in Idris.) >> > >> > What's wrong with this idea? I feel like *something* has to be more >> > complicated than I've made it seem! >> > >> > Richard >> > _______________________________________________ >> > ghc-devs mailing list >> > ghc-devs@haskell.org >> > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >> _______________________________________________ >> ghc-devs mailing list >> ghc-devs@haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >> > > > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs > >
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