- Haskell-Cafe - Haskell.org

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by Damien Mattei 20 Feb '19

20 Feb '19

in my previous message instead of 'hat' we must read 'add' ... gasp...

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Deadline extension: DBPL 19
by Alvin Cheung 20 Feb '19

20 Feb '19

Due to multiple requests, we are extending the deadline for *both* paper tracks to *Monday Feb 25* (anytime on Earth). Please feel free to submit via our hotcrp website. Questions can be directed to dbpl19-pcchairs(a)cs.washington.edu . ---------------------------------------------------------------------- The 17th International Symposium on Database Programming Languages https://pldi19.sigplan.org/track/dbpl-2019-papers Phoenix, Arizona, USA June 23, 2019 hosted as part of PLDI 2019 Call for Papers For over 25 years, DBPL has established itself as the principal venue for publishing and discussing new ideas at the intersection of databases and programming languages. Many key contributions in query languages for object-oriented data, persistent databases, nested relational data, and semistructured data, as well as fundamental ideas in types for query languages, were first announced at DBPL. Today, this creative research area is broadening into a subfield of data-centric computation, currently scattered among a range of venues. DBPL is an established destination for such new ideas and solicits submissions from researchers in databases, programming languages or any other community interested in the design, implementation or foundations of data-centric computation. Scope ----- DBPL solicits practical and theoretical papers in all topics at the intersection of databases and programming languages. Papers emphasizing new topics or emerging areas are especially welcome. Suggested, but not exclusive, topics of interest for submissions include: - Compiling Query Languages to Modern Hardware - Data-Centric Programming Abstractions, Comprehensions, Monads - Data Integration, Exchange, and Interoperability - Data Synchronization and Bidirectional Transformations - Declarative Data Centers (e.g., distributed query processing, serverless computing platforms, social computing platforms, etc) - Emerging and Nontraditional Data Models - Language-Based Security in Data Management - Language-Integrated Query Mechanisms - Managing Uncertain and Imprecise Information - Metaprogramming and Heterogeneous Staged Computation - Programming Language Support for Data-Centric Programming (e.g., databases, web programming, machine learning, etc) - Query Compilation and In-memory Databases - Query Language Design and Implementation - Query Transformation and Optimization - Schema Mapping and Metadata Management - Semantics and Verification of Database Systems - Stream Data Processing and Query Languages - Type and Effect Systems for Data-Centric Programming Author Guidelines ----------------- Prospective authors are invited to submit full papers in English presenting original research. Submitted papers must be unpublished and not submitted for publication elsewhere. Submissions should be no more than 10 pages long, excluding references, in the two-column ACM proceedings format, following PLDI's formatting requirements (https://pldi19.sigplan.org/track/pldi-2019-papers#Call-for-Papers) Each submission should begin with a succinct statement of the problem and a summary of the main results. Authors may provide more details to substantiate the main claims of the paper by including a clearly marked appendix at the end of the submission, which is not included in the page limit and is read at the discretion of the committee. At least one author of each accepted paper must attend the symposium to present their work. Short papers of at most 4 pages (same format as long papers) describing work in progress, demos, research challenges or visions are also welcome. Accepted short papers may be included or excluded from the formal proceedings, whichever the author(s) prefer. Full and short papers are both due on the deadline, February 25, 2019. Instructions on how to submit will be posted on the symposium website noted above. Review is single-blind, so authors do not need to anonymize their submissions. PC submissions are allowed, except for the co-chairs. Important Dates --------------- - Paper Submission: February 25, 2019 - Notification: March 29, 2019 - Final versions due: April 16, 2019 - Symposium: June 23, 2019 Proceedings ----------- Accepted papers will appear as part of the PLDI Proceedings for DBPL 2019. Program Committee ----------------- *Program Co-Chairs* Alvin Cheung, University of Washington Kim Nguyen, Universite Paris-Sud *Program Committee* William Cook, University of Texas at Austin Vasiliki Kalavri, ETH Harshad Kasture, Oracle Oleg Kiselyov, University of Tsukuba Sam Lindley, University of Edinburgh Tiark Rompf, Purdue University Stefanie Scherzinger, OTH Regensberg Amir Shaikhha, EPFL / University of Oxford Avi Shinnar, IBM Guido Wachsmuth, Oracle Melanie Wu, Pomona College History ------- The 17th Symposium on Data Base Programming Languages (DBPL 2019) continues the tradition of excellence initiated by its predecessors in Roscoff, Finistere (1987), Salishan, Oregon (1989), Nafplion, Argolida (1991), Manhattan, New York (1993), Gubbio, Umbria (1995), Estes Park, Colorado (1997), Kinloch Rannoch, Scotland (1999), Marino, Rome (2001), Potsdam, Germany (2003), Trondheim, Norway (2005), Vienna, Austria (2007), Lyon, France (2009), Seattle, Washington (2011), Riva del Garda, Italy (2013), Pittsburgh, Pennsylvania (2015), Munich, Germany (2017). DBPL was affiliated with VLDB from 1999-2013 and in 2017. In 2015, it is affiliated with SPLASH for the first time and in 2019, it is affiliated with PLDI for the first time.

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ANNOUNCE: eccrypto 0.1.0, timing attack safe cryptography in Haskell
by Marcel Fourné 19 Feb '19

19 Feb '19

Dear Haskell Community! I'd like to introduce some new cryptographic code, containing a verified[*] timing-attack safe pure Haskell[**] implementation of Ed25519 and as of yet unverified implementations of textbook ECDH and ECDSA on the NIST prime curves. Install it by $ cabal install eccrypto or download it from Hackage[0]. Also contained are test vectors, usable by the trusty $ cabal test as well as benchmarking code which you can invoke by $ cabal bench if you want to try my code before using it. Please note that this is a one person project, so there is still much room for optimization. The intended focus groups are implementors of cryptographic protocols as well as other cryptographers and interested third parties. My code uses no[**] embedded C code or assembly to achieve timing attack resistance, only careful Haskell constructions in the internal modules, the obligatory hackers footgun included only in those. ;-) Security sketch: The timing attack safety is built on the constant time criterion, namely, that no branches or memory access indices may be based on the content of the secret key bits. The name of this criterion is from the strict evaluation world of cryptography, but does not prohibit non-strict evaluation semantics per se. The API is only slightly different from contemporary libraries like "ed25519"[1], but the content of the signatures is just the same. The number of dependencies are also in the same ballpark, if you'd like to use the code for infrastructure - but in that case, please talk to me to not use unverified/insecure operations! Best of wishes to a thriving community, Marcel Fourné [*]: paper upcoming but as of now it only exists in my notes; analysis was done "by hand" on assembly generated by GHC 8.4.4, mechanization based on established proofs is planned [**]: using integer-gmp, might change in the future to low-level Haskell [0]: https://hackage.haskell.org/package/eccrypto-0.1.0 [1]: https://hackage.haskell.org/package/ed25519

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Looking for JavaScript(V8)-compilant parser
by Javran Cheng 19 Feb '19

19 Feb '19

Hi Cafe, tl;dr: I'm wondering if there are existing parsers for parsing any dateString that can be accepted by `Date.parse` of JavaScript(V8). The input looks like "Fri, 08 February 2019 12:34:56 +0900". At first I checked [MDN]( https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Ob…) and turns out it's very close to [IETF-compliant RFC 2822 timestamps]( https://tools.ietf.org/html/rfc2822#page-14) but not quite: as I then found [hsemail]( http://hackage.haskell.org/package/hsemail-2/docs/Text-Parsec-Rfc2822.html) to be promising, but it rejected "Fri, 08 February 2019 12:34:56 +0900" but accepted "Fri, 08 Feb 2019 12:34:56 +0900" (notice that RFC2822 does not accept full month name). Refering to language spec doesn't help ( http://www.ecma-international.org/ecma-262/5.1/#sec-15.9.4.2) as it doesn't mention RFC2822 at all. So it seems `Data.parse` accepts a superset of RFC2822 and a version of ISO8601 (as described in MDN above) but I'm not sure what exactly is the accepting set of inputs. Before I start working on a quick and dirty solution (it should work patching hsemail to accept full month name) I want to know if there are existing parsers for this purpose? Thanks! -- Javran (Fang) Cheng

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Amazonka: is it possible to work around deserialisation bug?
by Magnus Therning 18 Feb '19

18 Feb '19

I just created issue #517 on Amazonka [^1] which got me thinking. Is my only option to wait for the bug to be fixed or can I hack my way around it? I looked around in the documentation for Amazonka a bit but failed to find some obvious way to hack together a "send this request but give me the response in JSON". Which is why I'm trying my luck here. I suspect I'm not the first Amazonka user to find myself in this situation, so hopefully someone's got a solution already. /M [^1]: https://github.com/brendanhay/amazonka/issues/517 -- Magnus Therning OpenPGP: 0x927912051716CE39 email: magnus(a)therning.org twitter: magthe http://magnus.therning.org/ Computers are useless. They can only give you answers. — Pablo Picasso

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Re: [Haskell-cafe] Need help understanding a GADT related error
by David Banas 18 Feb '19

18 Feb '19

Hilco, Your first error arrises, because you’re offering to the caller of `h` that she may demand any type of `a`, but are “hard-wiring” `a :: T E` in the definition of that function. Reflecting that fact in the function type signature eliminates the error: -- h :: H (T a) h :: H (T E) h [] = (E' (E "E"), []) h (head:rest) = (E' (E ("E")), rest) Your second error is explained (I hope) in the comments I’ve added to your original code: tt' :: [Char] -> [T a] tt' = tt h [a, b] -- tt :: H t -> [P Char t] -> TT t -- :: ([Char] -> (t, [Char])) -> [P Char t] -> [Char] -> [t] -- -- h :: [Char] -> (t, [Char]) ~ H (T E) -- h :: [Char] -> (t, [Char]) ~ [Char] -> (T E, [Char]) -- ==> t ~ T E -- -- [a, b] :: [P Char t] -- a :: P Char (T E) /~ P Char (T A) -- b :: P Char (T E) /~ P Char (T B) -db

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Need help understanding a GADT related error
by Hilco Wijbenga 18 Feb '19

18 Feb '19

Hi all, I created some GADT code (see https://pastebin.com/vkJ3RzNA and below). When compiling this I get these errors: $ stack build parser-0.1.0.0: build (exe) Preprocessing executable 'parser' for parser-0.1.0.0.. Building executable 'parser' for parser-0.1.0.0.. [2 of 2] Compiling Main ( src/Main.hs, .stack-work/dist/x86_64-linux-tinfo6/Cabal-2.2.0.1/build/parser/parser-tmp/Main.o ) /home/hilco/workspaces/haskell/parser/src/Main.hs:30:18: error: • Couldn't match type ‘a’ with ‘E’ ‘a’ is a rigid type variable bound by the type signature for: h :: forall a. H (T a) at src/Main.hs:29:1-12 Expected type: T a Actual type: T E • In the expression: E' (E "E") In the expression: (E' (E "E"), []) In an equation for ‘h’: h [] = (E' (E "E"), []) • Relevant bindings include h :: H (T a) (bound at src/Main.hs:30:1) | 30 | h [] = (E' (E "E"), []) | ^^^^^^^^^^ /home/hilco/workspaces/haskell/parser/src/Main.hs:34:16: error: • Couldn't match type ‘B’ with ‘A’ Expected type: P Char (T A) Actual type: P Char (T B) • In the expression: b In the second argument of ‘tt’, namely ‘[a, b]’ In the expression: tt h [a, b] | 34 | tt' = tt h [a, b] | ^ -- While building custom Setup.hs for package parser-0.1.0.0 using: /home/hilco/.stack/setup-exe-cache/x86_64-linux-tinfo6/Cabal-simple_mPHDZzAJ_2.2.0.1_ghc-8.4.3 --builddir=.stack-work/dist/x86_64-linux-tinfo6/Cabal-2.2.0.1 build exe:parser --ghc-options " -ddump-hi -ddump-to-file -fdiagnostics-color=always" Process exited with code: ExitFailure 1 Why is "T a" not a more generic version of "T E"? Why doesn't "T E + T A + TB" yield "T a" as a generic type? Cheers, Hilco 1 {-# LANGUAGE GADTs #-} 2 3 module Main where 4 5 data PR t a = PR (Maybe ([t], a)) 6 data P t a = P ([t] -> PR t a) 7 8 a :: P Char (T A) 9 a = undefined 10 11 b :: P Char (T B) 12 b = undefined 13 14 data A = A 15 data B = B 16 data E = E String 17 18 data T a where 19 A' :: T A 20 B' :: T B 21 E' :: E -> T E 22 23 type H t = [Char] -> (t, [Char]) 24 type TT t = [Char] -> [t] 25 26 tt :: H t -> [P Char t] -> TT t 27 tt = undefined 28 29 h :: H (T a) 30 h [] = (E' (E "E"), []) 31 h (head:rest) = (E' (E ("E")), rest) 32 33 tt' :: [Char] -> [T a] 34 tt' = tt h [a, b] 35 36 main :: IO () 37 main = putStrLn "Hello"

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Re: [Haskell-cafe] Add newtype for Alternative using QuantifiedConstraints in base-4.13
by Ruben Astudillo 18 Feb '19

18 Feb '19

I wonder if it is useful at all. If `f a` already has a Monoid instance, you can use `(<>)` already instead of (<|>) with pretty much the same laws. Plus you don't have to import `(<>)` as it comes from the Prelude where `(<|>)` doesn't. Does this have an use case or is just for aesthetic completeness? -- -- Ruben -- pgp: 4EE9 28F7 932E F4AD

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Updating the dom-lt package
by Andreas Klebinger 17 Feb '19

17 Feb '19

I would like to have a updated version of dom-lt ( http://hackage.haskell.org/package/dom-lt ) on hackage. Matt Morrow uploaded the last version in 2009 and it has since become incompatible with current container versions. I'm posting here to make it known that I plan to take over the package to upload an update if I fail to reach him and he doesn't respond. (Which seems likely since the the domain is expired). Cheers Andreas Klebinger

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Call For Presentations: Compose NYC, June 24-25, 2019
by MightyByte 17 Feb '19

17 Feb '19

Compose is a conference focused specifically on strongly typed functional programming languages. It will be held in New York on Monday and Tuesday, June 24 -25, 2019. Registration will be open shortly. http://www.composeconference.org/201 ( http://www.composeconference.org/2017 ) 9 To get a sense of Compose, you can check out the great talks from past conferences: https://www.youtube.com/channel/UC0pEknZxL7Q1j0Ok8qImWdQ ( https://www.youtube.com/channel/UC0pEknZxL7Q1j0Ok8qImWdQ ) Below is our call for presentations. http://www.composeconference.org/2019/cfp/ ( http://www.composeconference.org/2016/cfp/ ) In past years, we have also hosted an unconference over the weekend adjacent to the conference. The unconference details this year have not been finalized yet, but if you’re interested you may want to keep that in mind when making travel plans. *** Compose Conference NYC 2019 Call for Presentations June 24 -25, 2019 New York City The audience for Compose is people using Haskell, PureScript, OCaml, F#, SML, and other strongly typed functional programming languages who are looking to increase their skills or learn new technologies and libraries. Presentations should be aimed at teaching or introducing new ideas or tools. We are also interested in presentations aiming at taking complex concepts, such as program derivation, and putting them into productive use. However presentations on anything that you suspect our audience may find interesting are welcome. The following are some of the types of talks we would welcome: *Library/Tool Talks* — Exploring the uses of a powerful toolkit or library, be it for parsing, testing, data access and analysis, or anything else. *Production Systems* — Experience reports on deploying functional techniques in real systems; insights revealed, mistakes made, lessons learned. *Theory made Practical* — Just because it’s locked away in papers doesn’t mean it’s hard! Accessible lectures on classic results and why they matter to us today. Such talks can include simply introducing the principles of a field of research so as to help the audience read up on it in the future; from abstract machines to program derivation to branch-and-bound algorithms, the sky’s the limit. Check out the Compose YouTube channel ( https://www.youtube.com/playlist?list=PLNoHgLVTxtaoolkQo4hLy4ZsA1prUJ51m ) to see videos of talks we've had previously and get an idea of the kinds of topics we usually feature. We also welcome presentations for more formal tutorials. Tutorials should be aimed at a smaller audience of beginner-to-novice understanding, and ideally include hands-on exercises. The due date for submissions is *April 23, 2019*. We will send out notice of acceptance by *April 30th*. We prefer that submissions be via the EasyChair website ( https://easychair.org/conferences/?conf=compose2019 ( https://easychair.org/conferences/?conf=compose2019 ) ). Please suggest a title, and describe the topic you intend to speak on. Talks can be either 30 or 45 minutes, please indicate how much time you would prefer to take. You may submit multiple talks if you have several ideas and are unsure which would be the most likely to be accepted. Accepted talks will be asked to submit slides for review prior to the conference. Feel free to include any additional information on both your expertise and interesting elements of your topic that would be appropriate for inclusion in the public abstract. Furthermore, if your abstract doesn't feel "final"—don't worry! We'll work with you to polish it up. If you want to discuss your presentation(s) before submitting, or to further nail down what you intend to speak on, please feel free to contact us at nyc(a)composeconference.org ( nyc(a)composeconference.org ). We're happy to work with you, even if you are a new or inexperienced speaker, to help your talk be great. Diversity We would like to put an emphasis on soliciting a diverse set of speakers - anything you can do to distribute information about this CFP and encourage submissions from under-represented groups would be greatly appreciated. We welcome your contributions and encourage you to apply! Best, Doug Sent via Superhuman ( https://sprh.mn/?vip=mightybyte@gmail.com )

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