September 2014 - ghc-devs

PROPOSAL: Make Data.Type.Bool.If polykinded
by Merijn Verstraaten 03 Sep '14

03 Sep '14

Ola! Currently we have: type family If cond tru fls where If True tru fls = tru If False tru fls = fls Unfortunately, this appears to turned into a monomorphicly kinded type family by GHC, which means it’s impossible to do foo :: If cond () (“Condition does not hold” ~ “”) => Foo -> Bar or similar fancy constraints. I hereby propose altering If to: type family If (cond :: Bool) (tru :: k) (fls :: k) :: k where If True tru fls = tru If False tru fls = fls Allowing it to work with kinds other than *. Discussion period: 2 weeks? Seems like a minor change. Cheers, Merijn

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deriving Bits
by Kazu Yamamoto 03 Sep '14

03 Sep '14

Hi, Recently, I found that we can put Bits in "deriving". I checked the GHC manual but it seems to me that this page does not cover Bits: https://www.haskell.org/ghc/docs/7.8.3/html/users_guide/deriving.html Are there any other classes which can be automatically derived and are not listed in this page? If the number of such classes is not large, how about adding them to this page? --Kazu

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wORD_SIZE vs platformWordSize of targetPlatform
by Johan Tibell 02 Sep '14

02 Sep '14

Hi, We seem to have two ways to get the same piece of information. We can get the target (?) word size as wORD_SIZE but there's also the platformWordSize field in the Platform data type, which is held as targetPlatform in DynFlags. Which one should I use? Most code uses wORD_SIZE. -- Johan

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Proposal: run GHC API tests on fast
by Edward Z. Yang 02 Sep '14

02 Sep '14

Currently, most GHC API tests are not run on 'make fast', ostensibly because linking against the GHC API can take a while. I propose that change this, and run GHC API tests by default. Reasons: 1. The GHC API is closely tied a lot of internal structure of GHC, so it's very easy to make a change, track it through the rest of the compiler, but forget to update the tests/documentation. 2. We can boost this into poor man's testable documentation. The idea is to duplicate all GHC API examples in the manual in the test suite, and have a comment on all of the examples asking the developer to update the manual. (Or we could automatically extract the snippets from the manual, but that's work and this I could do in a few minutes.) 3. I don't think running these tests will add that much extra run time to the test suite; certainly interactively the time spent linking is unnoticeable. Let's set a one week discussion period for this proposal. Thanks, Edward

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Re: [Haskell] ANNOUNCE: GHC version 7.8.3
by Bryan O'Sullivan 02 Sep '14

02 Sep '14

On Fri, Jul 11, 2014 at 6:40 AM, Austin Seipp <austin(a)well-typed.com> wrote: > The GHC Team is pleased to announce a new patchlevel release of GHC, 7.8.3. > haddock 2.14.3 that ships with it seems to be quite broken. Perhaps it's a bad interaction with cabal, it's hard to say from the outside, but here are some details. Here's the kind of error I get from haddock when I try to use cabal to install a package (primitive, in this case): module ‘primitive-0.5.3.0:Main’ is defined in multiple files: dist/build/tmp-92638/Control/Monad/Primitive.hs dist/build/tmp-92638/Data/Primitive/MachDeps.hs dist/build/tmp-92638/Data/Primitive/Types.hs dist/build/tmp-92638/Data/Primitive/Array.hs dist/build/tmp-92638/Data/Primitive/ByteArray.hs dist/build/tmp-92638/Data/Primitive/Internal/Compat.hs The result is that I have no haddock docs for any packages now :-(

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cons/build and making rules look boring
by David Feuer 01 Sep '14

01 Sep '14

I think I may have figured out at least part of the reason that cons/build gives bad results. I actually ran into a clue when working on scanl. It seems at least part of the problem is that a rule like x : build g = build (\c n -> c x (g c n)) makes (:) look "interesting" to the inliner. Unfortunately, as I discovered after much extreme puzzlement about why rules relating to scanl were affecting things that had nothing to do with scanl, it turns out that making (:) look interesting is really quite bad, and something that we probably never want to happen. As a result, the only ways I see to try to make rules like that work properly are 1. If constructors are *always* best treated as boring, and the inliner knows when's a constructor, make it treat them all as boring. 2. Offer a BORINGRULE annotation to indicate that the rule should not make its LHS "interesting", or 3. (I don't like this option much) Make a special case forcing (:) in particular to be boring. David

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RE: [commit: ghc] master: Bump haddock.base max_bytes_used (8df7fea)
by Simon Peyton Jones 01 Sep '14

01 Sep '14

Urk. It's quite surprising that this particular change would increase allocation significantly. I wonder whether it just pushed it over the threshold. Simon | -----Original Message----- | From: ghc-commits [mailto:ghc-commits-bounces@haskell.org] On Behalf Of | git(a)git.haskell.org | Sent: 01 August 2014 18:57 | To: ghc-commits(a)haskell.org | Subject: [commit: ghc] master: Bump haddock.base max_bytes_used (8df7fea) | | Repository : ssh://git@git.haskell.org/ghc | | On branch : master | Link : | http://ghc.haskell.org/trac/ghc/changeset/8df7fea7cf8a32d54ac3d6772432273 | 8595bf421/ghc | | >--------------------------------------------------------------- | | commit 8df7fea7cf8a32d54ac3d67724322738595bf421 | Author: Joachim Breitner <mail(a)joachim-breitner.de> | Date: Fri Aug 1 19:55:52 2014 +0200 | | Bump haddock.base max_bytes_used | | It has reliably increased with commit 1ae5fa45, and has been stable | since then, so it does not seem to be a fluke. I did not investigate | why | that commit might have increased this value. | | | >--------------------------------------------------------------- | | 8df7fea7cf8a32d54ac3d67724322738595bf421 | testsuite/tests/perf/haddock/all.T | 13 +++++++------ | 1 file changed, 7 insertions(+), 6 deletions(-) | | diff --git a/testsuite/tests/perf/haddock/all.T | b/testsuite/tests/perf/haddock/all.T | index b17d472..49321b9 100644 | --- a/testsuite/tests/perf/haddock/all.T | +++ b/testsuite/tests/perf/haddock/all.T | @@ -17,13 +17,14 @@ test('haddock.base', | # 2014-01-22: 168 (x86/Linux - new haddock) | # 2014-06-29: 156 (x86/Linux) | ,stats_num_field('max_bytes_used', | - [(wordsize(64), 115113864, 10) | - # 2012-08-14: 87374568 (amd64/Linux) | - # 2012-08-21: 86428216 (amd64/Linux) | - # 2012-09-20: 84794136 (amd64/Linux) | - # 2012-11-12: 87265136 (amd64/Linux) | - # 2013-01-29: 96022312 (amd64/Linux) | + [(wordsize(64), 127954488, 10) | + # 2012-08-14: 87374568 (amd64/Linux) | + # 2012-08-21: 86428216 (amd64/Linux) | + # 2012-09-20: 84794136 (amd64/Linux) | + # 2012-11-12: 87265136 (amd64/Linux) | + # 2013-01-29: 96022312 (amd64/Linux) | # 2013-10-18: 115113864 (amd64/Linux) | + # 2014-07-31: 127954488 (amd64/Linux), correlates with | 1ae5fa45 | ,(platform('i386-unknown-mingw32'), 58557136, 10) | # 2013-02-10: 47988488 (x86/Windows) | # 2013-11-13: 58557136 (x86/Windows, | 64bit machine) | | _______________________________________________ | ghc-commits mailing list | ghc-commits(a)haskell.org | http://www.haskell.org/mailman/listinfo/ghc-commits

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