- Haskell-Cafe - Haskell.org

[ANN] servant 0.4.0 released (+new website)
by Alp Mestanogullari 10 May '15

10 May '15

Hello everyone, We're happy to announce the releases of: - servant 0.4.0 - servant-server 0.4.0 - servant-client 0.4.0 - servant-jquery 0.4.0 - servant-docs 0.4.0 - servant-blaze 0.4.0 - servant-lucid 0.4.0 to Hackage. As well as a new website, same URL as before: http://haskell-servant.github.io/ -- which features a tutorial that's much more informative than the getting started we had for the previous version. The tutorial is available at http://haskell-servant.github.io/tutorial The highlights for this release are: - Multiple content-types support (with servant-blaze and servant-lucid offering a way to encode data for the HTML content type) - Handlers in other monads than `EitherT` - Response headers support - Safe links to endpoints - Saner types for aborting early in request handlers (the `Left` branch in `EitherT`) For more details about the new features, please read the release post: http://haskell-servant.github.io/posts/2015-05-10-servant-0.4-released.html Cheers -- Alp Mestanogullari

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How to estimate number of downloads of GHC or Haskell Platform?
by nr＠cs.tufts.edu 10 May '15

10 May '15

For a review, I'm trying to get a rough estimate of how many times GHC or the Haskell Platform have been downloaded. Although I'm sure I've seen this information graphed over time at workshops, my web-search skills are not turning up anything. I'd be quite happy to get an estimate to within a factor of ten. Can anyone suggest any sources, or a good way to estimate this number? Norman

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Using ClassyPrelude to handle either Text or ByteString
by Mike Meyer 09 May '15

09 May '15

Ok, I can't seem to figure out how to make this work, and since I'm using ClassyPrelude (from classy-prelude, latest version on hackage as of yesterday), I think cafe is a better place to ask than beginners. Sorry if this should have gone there. I want to read in a list of files, concatenate them, and then run the resulting data through a "process" function. So far, no problem. Given an opts record that contains the list of files and some control for the process function, this expression works: hPut stdout =<< process opts . concat <$> mapM (readFile . fpFromString) (files opts) (BTW, recommendations on cleaning that up gratefully accepted) However, I'd like to be able to read them all as either Text or ByteString, depending on options being passed to me. This doesn't work so well. If I give process a type of Text -> Text or ByteString->ByteString, everything works fine with no other changes. However, any attempt to make it polymorphic fails with ambiguous type warnings. I've tried a slew of things, and found a few that work. But none of them are what I'd call good, much less elegant. Is there a good way to do this?

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Re: [Haskell-cafe] RFC: "Native -XCPP" Proposal
by Herbert Valerio Riedel 08 May '15

08 May '15

Hello Christian, (I've re-CC'ed haskell-cafe, assuming this wasn't deliberate) On 2015-05-08 at 09:50:46 +0200, Christian Maeder wrote: > using cpphs is the right way to go! > > Rewriting it from scratch may be a good exercise but is (essentially) a > waste of time. > > However, always asking Malcolm to get source changes into cpphs would > be annoying. > > Therefore it would be great if the sources were just part of the ghc > sources (under git). > > Another "problem" might be the dependency "polyparse" that is currently > not part of the core libraries. A scheme was actually discussed privately to address this: We certainly don't want to expose cpphs/polyparse (and text!) as new packages in GHC's global pkg-db. Which we'd end up, if we handled cpphs as the other exposed boot libraries. Therefore we'd only use the few relevant modules from cpphs/polyparse as "other-modules" (i.e. internal hidden dependencies -- i.e. we wouldn't use cpphs/polyparse's .cabal files) compiled into GHC, but not exposed. We'd either create a new Git submodule to hold our "fork" of cpphs/polyparse, or just add it somewhere inside ghc.git > (I guess that replacing polyparse by something else would also be a nice > exercise.) > > So (for me) the only question is, if Malcolm is willing to transfer > control over cpphs to the haskell-community (or ghc head) - of course > with due acknowledgements! I don't think this will be necessary, as we don't need the cpphs-upstream to mirror each modifications immediately. The benefit of the scheme described above is that we'd be somewhat decoupled from cpphs' upstream, and can freely experiment in our "fork", and can sync up with Malcolm from time to time to merge improvements in both directions. -- hvr

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status of deb.haskell.org?
by Jeremy 08 May '15

08 May '15

The haskell status page says that deb.haskell.org has been down since mid-February. Are there any plans to bring it back up? -- View this message in context: http://haskell.1045720.n5.nabble.com/status-of-deb-haskell-org-tp5768430.ht… Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.

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Re: [Haskell-cafe] RFC: "Native -XCPP" Proposal
by Howard B. Golden 08 May '15

08 May '15

At the risk of antagonizing some (most? all?) of you, how about... -XCPP stands for the native CPP -XGNUCPP stands for GNU's GCC CPP -XClangCPP stands for Clang's CPP -XCPPHS stands for CPPHS ... with the hope that TH is the future? Howard

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Efficient memory use for tens of thousands of connections
by Ben Bangert 08 May '15

08 May '15

I'm currently evaluating memory overhead for a variety of simple Websocket based echo server to get a gauge of minimal memory penalty per connection along with SSL overhead per connection. I've created two websocket servers in Haskell: https://github.com/bbangert/ssl-ram-testing/tree/master/Haskell One using Yesod + jaspers Websockets lib, the other with Yesod + Mishael Snoyman's native websocket lib. I was curious what options I might be missing that would ensure a more efficient use of memory, at the moment the non-SSL seems to use about 48kb per connection, while using Haskell's TLS via warp-tls introduces a huge amount of overhead (along with odd handshake issues). Here's what my results look like: No SSL Program started. Tester started. Tester finished connecting. Waiting: 360 Last Memory Increase: 2 WARNING: Program hasn't stopped increasing. Started with: 2633728 Ended with: 50896896 kB per connection: 47.13 SSL Program started. Tester started. yesod-customws-tls: HandshakeFailed (Error_Protocol ("bad record mac",True,BadRecordMac)) yesod-customws-tls: HandshakeFailed (Error_Protocol ("bad record mac",True,BadRecordMac)) yesod-customws-tls: HandshakeFailed (Error_Protocol ("bad record mac",True,BadRecordMac)) yesod-customws-tls: HandshakeFailed (Error_Protocol ("bad record mac",True,BadRecordMac)) yesod-customws-tls: HandshakeFailed (Error_Protocol ("bad record mac",True,BadRecordMac)) yesod-customws-tls: HandshakeFailed (Error_Protocol ("bad record mac",True,BadRecordMac)) yesod-customws-tls: HandshakeFailed (Error_Protocol ("bad record mac",True,BadRecordMac)) yesod-customws-tls: HandshakeFailed (Error_Protocol ("bad record mac",True,BadRecordMac)) WARNING: Failed to connect all clients Tester finished connecting. Waiting: 360 Last Memory Increase: 4 WARNING: Program hasn't stopped increasing. Started with: 3170304 Ended with: 454221824 kB per connection: 444.03 SSL Overhead per Conn: 396.90 I wait up to 6 minutes for memory to level out, it never does with or without SSL. Is this expected behavior? If not, what options am I missing? The ssl-ram-testing repo includes full directions on how to reproduce this and run this test. Cheers, Ben

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ANN: Important lambabot update (5.0.2.1 release)
by Bertram Felgenhauer 08 May '15

08 May '15

Hi, I've just released lambdabot-5.0.2.1 which plugs an embarrassing security hole in the @check command; if you are running lambdabot as an IRC bot, you should upgrade! Generally, lambdabot relies on SafeHaskell and not running user-supplied IO actions for safety. This is unlikely to be bullet-proof, so it's advisable to sandbox mueval. However, the @check command violated this basic principle, and allowed running arbitrary IO actions. This is now fixed by using the (new) QuickCheck-safe package that only uses unsafePerformIO for the specific purposes of catching exceptions and generating the initial seed for random number generation. Thanks to benzfr on Freenode for finding this! There are a few minor changes. Notably, we now ship compiler-specific versions of Pristine.hs so that lambdabot runs out of the box on both ghc-7.6.3 and ghc-7.8.3 (ghc-7.10.1 still needs some work.) and the dict plugin no longer supports looking up several words at once. Cheers, Bertram P.S. As I just realized, I forgot to update the Changelog that comes with lambdabot... will try to remember next time.

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Cannot run GHC-7.10.1 tests
by Jeremy Henty 07 May '15

07 May '15

I successfully built GHC-7.10.1 but I cannot run the tests (at least not when I follow the instructions at https://ghc.haskell.org/trac/ghc/wiki/Building/RunningTests) "make fast" fails like this: ===--- building phase 0 make -r --no-print-directory -f ghc.mk phase=0 phase_0_builds make[1]: Nothing to be done for `phase_0_builds'. ===--- building phase 1 make -r --no-print-directory -f ghc.mk phase=1 phase_1_builds make[1]: Nothing to be done for `phase_1_builds'. ===--- building final phase make -r --no-print-directory -f ghc.mk phase=final fast make[1]: *** No rule to make target `fast'. Stop. make: *** [fast] Error 2 "make testfast" fails in exactly the same way, except that the broken make target is "testfast" instead of fast. "make test" and "make fulltest" fail like this: make -C testsuite/tests CLEANUP=1 OUTPUT_SUMMARY=../../testsuite_summary.txt fast make[1]: Entering directory `/data/build.d/6.8/ghc-7.10.1/testsuite/tests' ../mk/boilerplate.mk:168: ../mk/ghcconfig_data_build.d_6.8_ghc-7.10.1_inplace_bin_ghc-stage2.mk: No such file or directory ../mk/ghc-config "/data/build.d/6.8/ghc-7.10.1/inplace/bin/ghc-stage2" >"../mk/ghcconfig_data_build.d_6.8_ghc-7.10.1_inplace_bin_ghc-stage2.mk"; if [ $? != 0 ]; then rm -f "../mk/ghcconfig_data_build.d_6.8_ghc-7.10.1_inplace_bin_ghc-stage2.mk"; exit 1; fi /bin/sh: ../mk/ghc-config: cannot execute binary file make[1]: *** [../mk/ghcconfig_data_build.d_6.8_ghc-7.10.1_inplace_bin_ghc-stage2.mk] Error 1 make[1]: Leaving directory `/data/build.d/6.8/ghc-7.10.1/testsuite/tests' make: *** [test] Error 2 Interestingly, for GHC-7.8.4 "make fast" and "make testfast" fail in exactly the same way but "make test" and "make fulltest" both work. So, how do I test GHC-7.10.1 ? Regards, Jeremy Henty

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Re: [Haskell-cafe] release timing
by Harry . 07 May '15

07 May '15

Simon PJ wrote ... > > | It would be nice to see #8224 in as well, but doesn't look like that's > | going to be fixed any time soon! Have GHC HQ ever considered asking > | Intel if they'd be willing to lend a hand? > > What makes you think that Intel would help with #8224? (It's about the IO manager.) The title is about the IO manager :-) The diagnosis ends with performance issues that appear tied to CPU design, something that Intel ought to know something about. > Also, GHC is an open source project. You don't have to wait for GHC HQ to do anything --- please go ahead and ask anyone you think could help! While it's not unheard of for a corporation to assist an open source project, particularly with issues specific to their products, the request would have a lot more credibility if it came from GHC HQ than a random GHC user. I also have no idea who in Intel should be contacted for such things. But in the spirit of your suggestion I'm cross-posting this to haskell-cafe to reach a wider audience. Does anyone out there know of a contact in Intel who might be able/willing to help with CPU performance issues?

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