Re: Pattern synonyms for 7.8?

Hi Gergo, I went ahead and pushed the preliminary work to a new branch in the official repositories. GHC, haddock and testsuite now have a 'wip/pattern-synonyms' branch, where you can test the code: https://github.com/ghc/ghc/commits/wip/pattern-synonyms https://github.com/ghc/haddock/commits/wip/pattern-synonyms https://github.com/ghc/testsuite/commits/wip/pattern-synonyms Any intrepid parties are welcome to try it. A few things of note: 1) As Richard pointed out, the docs are under docs/users_guide, as well as the release notes. Please feel free to elaborate however you want on the feature and the bulletpoint for the release notes. 2) The failures are indeed a result of your code, in particular: driver T4437 [bad stdout] (normal) generics GenDerivOutput [stderr mismatch] (normal) generics GenDerivOutput1_0 [stderr mismatch] (normal) generics GenDerivOutput1_1 [stderr mismatch] (normal) rename/should_compile T7336 [stderr mismatch] (normal) The first four are just tests that need to be updated. T4437 needs to have PatternSynonyms listed (it tests the available extensions,) and the generics test have had their output slightly changed. This is because the generated terms are now annotated with the Origin type, specifying where they come from. Here's an example from GenDerivOutput1_1: ---------------------------- instance GHC.Generics.Selector CanDoRep1_1.S1_1_0Dd where - GHC.Generics.selName _ = "d11d" + (Generated, GHC.Generics.selName _ = "d11d") ---------------------------- I'm not actually sure if this is what we want. Should -ddump-deriv print this? I'm not sure we guarantee the output is syntactically valid anyway, but it's worth considering. Removing this from the output would mean these tests don't need any tweaks. Perhaps Simon or Pedro have something to say. 3) It seems GHCi does not support declaring pattern synonyms at the REPL. I'm not sure if it's intentional, but if it goes in like this, please be sure to document it in the release notes. We can file a ticket later for supporting pattern synonyms at the REPL. On Wed, Jan 8, 2014 at 1:14 PM, Richard Eisenberg wrote:

Hi Gergo,

As pattern synonyms are user-facing, you should update the user manual along with (perhaps) the wiki. The file to edit is docs/users_guide/glasgow_exts.xml. You should also add a note to docs/users_guide/7.8.1_notes.xml.

Apologies if someone has already said this to you.

Richard

On Jan 7, 2014, at 6:05 PM, Dr. ÉRDI Gergő wrote:

Hi,

Wow, so, I thought there would be some back-and-forth, then a decision, then I would go and walk the last mile and then formally submit the patch for review - and now I see that in <2 days all that has passed...

Of course I'll make validate pass, I just didn't even know about it. Likewise, I needed the carrot of 7.8 inclusion dangling before me to start writing the user docs.

One problem, though, is that I'll be on holiday from tomorrow, so I'll only have time to look into this tonight before next weekend. I'll try my best to fix up validate tonight, and I'll write the docs (which I hope will mostly be an editing job on the wiki) next week. How does that sound?

Thanks, Gergo

On Jan 8, 2014 3:41 AM, "Austin Seipp" wrote:

...

Hi Gergo,

Thanks for rebasing your changes. Unfortunately, they do not compile cleanly with ./validate, which we really need to have working for all incoming patches.

In particular, ./validate enables -Werror and a slew of warnings that you won't normally see during development, which greatly aids in keeping the code clean. One, for example, is that some of your commits introduce tabs - we ban tabs and validate errors on them!

Another: the problem is that in

https://github.com/gergoerdi/ghc/commit/afefa7ac948b1d7801d622824fbdd75ade2a..., you added a Monoid instance for UniqSet - but this doesn't work correctly. The problem is that UniqSet is just an alias for UniqFM (type UniqSet a = UniqFM a), so the instance is technically seen as an orphan. Orphan instances cause -Werror failures with ./validate (unless you disable them for that module, but here we really shouldn't.)

The fix is to write the Monoid instance for UniqFM directly in UniqFM.hs instead.

Likewise, here's a real bug that -Werror found in your patch in the renamer (by building with ./validate):

compiler/rename/RnBinds.lhs:744:1: Warning: Pattern match(es) are non-exhaustive In an equation for `renameSig': Patterns not matched: _ (PatSynSig _ _ _ _ _)

Indeed, renameSig in RnBinds doesn't check the PatSynSig case! The missing instance looks straightforward to implement, but this could have been a nasty bug waiting.

If you could please take the time to clean up the ./validate failures, I'd really appreciate it. I imagine it'll take very little time, and it will make merging much easier for me. An easy way to do it is just to check out your pattern-synonyms branches, then say:

$ CPUS=X sh ./validate

where 'X' is the number of cores, similar to 'make -jX'

If it fails, you can make a change, and keep going with:

$ CPUS=X sh ./validate --no-clean

and rinse and repeat until it's done.

Note the --no-clean is required, since `./validate` will immediately run `make distclean` by default if you do not specify it.

On Tue, Jan 7, 2014 at 5:50 AM, Dr. ERDI Gergo wrote:

...

On Mon, 6 Jan 2014, Carter Schonwald wrote:

...

as long as we clearly communicate that there may be refinements / breaking changes subsequently, i'm all for it, unless merging it in slows down 7.8 hitting RC . (its taken long enough for RC to happen... don't want to drag it out further)

If that helps, I've updated the version at https://github.com/gergoerdi/ghc (and the two sister repos https://github.com/gergoerdi/ghc-testsuite and https://github.com/gergoerdi/ghc-haddock) to be based on top of master as of today.

Bye, Gergo

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