December 2014 - ghc-devs

are patterns synonyms definable in GHCI?
by Carter Schonwald 18 Dec '14

18 Dec '14

Hey all, I was trying to define some pattern synonyms in ghci recently, and that doesnt seem to work. Is that something slated to be fix in 7.10 or something?

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Status updates
by Austin Seipp 18 Dec '14

18 Dec '14

Hi *, Here are some status updates: - I've merged the Applicative Monad patchset! Yay! Many thanks to Nathan Howell for helping me out in the end there. Please let me know if anything explodes horribly (I hope not). - Gabor has set up some build documentation for us based on HEAD, hooray! See here - http://haskell.inf.elte.hu/ - I still need to fix haskell.org/ghc to link to this properly (there may be other dead links, please let me know). - As I'm sure most of you were aware, it was a slow week due to ICFP & related events being most of last week. - As I'm also sure you were aware, Haskell.org suffered a lot of instability this past week. I've been focusing most of my efforts since about Thursday on this, since it's come and gone a lot and has needed some consistent monitoring. Unfortunately, it is not done yet, and there is still more work to be done. :( - ghc.haskell.org was migrated to a new server in the US as a part of this effort this weekend (send a thanks to Herbert). In general, you should notice nothing really new, but latency for UK citizens may be a bit higher than it was before now. - Now that Applicative/Monad is done, there are some more changes to 'base' that will happen (Bifunctors, Foldable/Traversable) that will need to happen. So I'm sure this discussion will start soon. - I still can't set up the Windows bot yet, sorry! Phabricator work is still not yet available upstream. Hopefully soon. - Sergei spent some time filing bugs that we should fix in the testsuite, because they fail --slow validate. I believe these are two of them: - https://ghc.haskell.org/trac/ghc/ticket/9567 - https://ghc.haskell.org/trac/ghc/ticket/9566 We'll probably need to fix these before we turn it on. Simon, these look like something up your alley... - For those who missed ICFP, Simon gave a nice status update for GHC, which is on YouTube: https://www.youtube.com/watch?v=Ex79K4lvJno&list=PL4UWOFngo5DW6nKDjK0UB5Oy9… -- Regards, Austin Seipp, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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Understanding DsMeta module
by Jan Stolarek 18 Dec '14

18 Dec '14

I'm implementing Template Haskell support for injective type families and I'm struggling to understand DsMeta module. It seems that all functions in that module delegate their calls to functions in Language.Haskell.TH.Lib via wired-in names and the `DsMeta.rep2` function. I'm puzzled by this design and I'd appreciate if someone could explain why things are done this way. Take this function example: repPlainTV :: Core TH.Name -> DsM (Core TH.TyVarBndr) repPlainTV (MkC nm) = rep2 plainTVName [nm] where `plainTvName` is a name of `Language.Haskell.TH.Lib.plainTV`: plainTV :: Name -> TyVarBndr plainTV = PlainTV Why not implement repPlainTV like this: ? repPlainTV :: Core TH.Name -> DsM (Core TH.TyVarBndr) repPlainTV (MkC nm) = return $ MkC (TH.PlainTV nm) Janek

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Re: [Diffusion] [Build Failed] rGHC726ea08a6e58: Amend TcPluginM interface
by Adam Gundry 18 Dec '14

18 Dec '14

On 18/12/14 09:25, Phabricator wrote: > Harbormaster failed to build B2694: rGHC726ea08a6e58: Amend TcPluginM interface! Sigh. It seems perf/compiler T3294 is failing on Harbormaster, but it validated fine locally on x86_64. I doubt my commit is responsible, and suspect this is just a wobbly test, but it's hard to know without the full build log. Is there a way to get full logs for failing Harbormaster builds? They seem to be uploaded only if the build succeeds. Thanks, Adam > USERS > adamgundry (Author) > GHC - Driver (Auditor) > GHC - Type checker/inferencer (Auditor) > > COMMIT > https://phabricator.haskell.org/rGHC726ea08a6e58 > > EMAIL PREFERENCES > https://phabricator.haskell.org/settings/panel/emailpreferences/ > > To: adamgundry, GHC - Driver, GHC - Type checker/inferencer -- Adam Gundry, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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RE: type-checker regression in GHC HEAD?
by Simon Peyton Jones 17 Dec '14

17 Dec '14

Ah yes! A palpable bug thank you. Fixing.. S | -----Original Message----- | From: Herbert Valerio Riedel [mailto:hvriedel@gmail.com] | Sent: 17 December 2014 10:01 | To: Simon Peyton Jones | Cc: Edward Kmett; Austin Seipp | Subject: Re: type-checker regression in GHC HEAD? | | Hello Simon, | | ...does that repro-case work for you? shall I create a Trac ticket as | well? I consider this one quite critical for this week's GHC 7.10.1 | RC, if it can't compile `lens` :-/ | | Cheers, | hvr | | On 2014-12-16 at 15:03:49 +0100, Herbert Valerio Riedel wrote: | > On 2014-12-16 at 14:33:00 +0100, Simon Peyton Jones wrote: | >> No immediate bells. | >> | >> Is it possible to reproduce it without compiling all lens's zillion | >> dependencies? | > | > it's actually easier to isolate than expected: | > | > {-# LANGUAGE UndecidableInstances #-} | > | > import Control.Applicative | > import Control.Category | > import Prelude hiding ((.),id) | > | > newtype FocusingPlus w k s a = FocusingPlus { unfocusingPlus :: k | > (s, w) a } | > | > instance Functor (k (s, w)) => Functor (FocusingPlus w k s) where | > fmap f (FocusingPlus as) = FocusingPlus (fmap f as) | > | > instance Applicative (k (s, w)) => Applicative (FocusingPlus w k | s) where | > pure = FocusingPlus . pure | > FocusingPlus kf <*> FocusingPlus ka = FocusingPlus (kf <*> ka) | > | > | > works with GHC 7.8, fails with GHC HEAD w/ | > | > repro.hs:13:25: | > Couldn't match type ‘f0’ with ‘k (s, w)’ | > ‘f0’ is untouchable inside the constraints () bound by the | type signature for pure :: a -> FocusingPlus w k s a at repro.hs:13:3- | 6 | > Expected type: a -> k (s, w) a | > Actual type: a -> f0 a | > Relevant bindings include pure :: a -> FocusingPlus w k s a | (bound at repro.hs:13:3) | > In the second argument of ‘(.)’, namely ‘pure’ | > In the expression: FocusingPlus . pure | > Failed, modules loaded: none. | | -- | "Elegance is not optional" -- Richard O'Keefe

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API Annotations D538 call for review
by Alan & Kim Zimmerman 16 Dec '14

16 Dec '14

Hi All https://phabricator.haskell.org/D538 is now ready for review/merge. It contains a number of small changes based on actually using the API annotations in ghc-exactprint [1] which is now able to perfectly reproduce the original source using only the ParsedSource AST and API annotations. [1] https://github.com/alanz/ghc-exactprint/tree/wip Regards Alan

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Customizing Phab
by Jan Stolarek 16 Dec '14

16 Dec '14

After working with Phab for a while I realize I'd like to customize layout of a revision. When I work with a revision I most often read comments and source code and write my replies (often based on comments). The problem is that comments are located at the top of a page whereas the text field for writing a reply is located at the bottom. I wonder if there is a way to: a) collapse "Revision Update History", "Local Commits", "Table of Contents" and "Open Revisions Affecting These Files"? b) or move them below "Leap Into Action" section ? I can't find any such settings so I suppose that's not possible by default. Is there any way to extend Phab's functionality do allow customizing layout in a way described above? Janek

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FW: [GHC] #9049: Expose srcLoc from the assertion architecture to allow better error messages
by Simon Peyton Jones 16 Dec '14

16 Dec '14

Devs I wish there was a way to convert Trac identities to people's name and email addresses. (For committers there is, https://ghc.haskell.org/trac/ghc/wiki/TeamGHC, but no one else.) As Eric says, I think most people would be happy to do that. I like addressing real people. And syncing up with separate email conversations is also a challenge. Simon -----Original Message----- From: ghc-tickets [mailto:ghc-tickets-bounces@haskell.org] On Behalf Of GHC Sent: 16 December 2014 10:46 Cc: ghc-tickets(a)haskell.org Subject: Re: [GHC] #9049: Expose srcLoc from the assertion architecture to allow better error messages #9049: Expose srcLoc from the assertion architecture to allow better error messages -------------------------------------+---------------------------------- -------------------------------------+--- Reporter: nh2 | Owner: gridaphobe Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.8.2 Component: Compiler | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: | Related Tickets: None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+---------------------------------- -------------------------------------+--- Comment (by gridaphobe): simonpj: This is Eric Seidel (eric at seidel.io). I've told trac my name and email, but it doesn't seem to expose them to others! I'd be happy to tick a "make my name+email public" box if there's one I'm missing somewhere. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9049#comment:14> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler _______________________________________________ ghc-tickets mailing list ghc-tickets(a)haskell.org http://www.haskell.org/mailman/listinfo/ghc-tickets

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Are empty statement lists allowed in recursive do? Possible bug
by Alan & Kim Zimmerman 16 Dec '14

16 Dec '14

I am trying to work out empirically whether empty statement lists are allowed in a stmtlist, and one of the points these are used in Parser.y is for recursive do. If I try to load the following ---------------- {-# LANGUAGE RecursiveDo #-} bar :: IO () bar = do rec {} return () ----------------------- into GHCI, I get a "Prelude.head: empty list" panic. I think this is related to `rnRecStmtsAndThen` If I try --------------------- bar :: IO () bar = do do {} return () ----------------------- I get a warning about empty do statements not being allowed. Hence the question as to wether recursive do should be allowed to have an empty statement list. I am trying to manage the API annotations for semicolons in statement lists, and the current way it is being parsed makes this difficult, I would prefer to simplify it to something like how import decls are parsed, which can also have multiple semicolons in between. Alan

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Last call for 7.8.4
by Austin Seipp 15 Dec '14

15 Dec '14

Hello *, I've just pushed a final round of patches to the 7.8 branch, including the notorious Cabal fix for the -fPIC bug that was discussed earlier in the week, and a handful of other bugfixes for ARM among other things (/cc Joachim :) I am planning on making the final 7.8.4 release this week; barring any pending minor issues (e.g. build wibbles) in the tree (which I do not think should be needed), the only thing I will commit is A) release notes and B) the version number changes. There will not likely be a 7.8.4-rc2, so this is a last call for any bugs you'd like to see fixed. I may have missed something -- Regards, Austin Seipp, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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