Well, as of 7.10.2 the GHC AST no longer has bottoms in it, so it can already be used quite easily
On Wed, Nov 11, 2015 at 9:53 PM, Thomas Bereknyei <tombe...@gmail.com> wrote: > 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 >> >> > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs > >
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