March 2020 - Haskell-Cafe

2nd Workshop on Formal Methods for Blockchains (FMBC) 2020 - First Call
by Bruno Bernardo 26 Mar '20

26 Mar '20

[ Please distribute, apologies for multiple postings. ] ======================================================================== 2nd Workshop on Formal Methods for Blockchains (FMBC) 2020 - First Call https://fmbc.gitlab.io/2020 July 19, 2020, Los Angeles, USA Co-located with the 32nd International Conference on Computer-Aided Verification (CAV 2020) http://i-cav.org/2020/ ------------------------------------------------------------- IMPORTANT DATES -------------------------------- Abstract submission: April 21, 2020 Full paper submission: April 28, 2020 Notification: June 9, 2020 Camera-ready: July 7, 2020 Conference: July 19, 2020 -------------------------------- -------------------------------- TOPICS OF INTEREST -------------------------------- Blockchains are decentralized transactional ledgers that rely on cryptographic hash functions for guaranteeing the integrity of the stored data. Participants on the network reach agreement on what valid transactions are through consensus algorithms. Blockchains may also provide support for Smart Contracts. Smart Contracts are scripts of an ad-hoc programming language that are stored in the Blockchain and that run on the network. They can interact with the ledger’s data and update its state. These scripts can express the logic of possibly complex contracts between users of the Blockchain. Thus, Smart Contracts can facilitate the economic activity of Blockchain participants. With the emergence and increasing popularity of cryptocurrencies such as Bitcoin and Ethereum, it is now of utmost importance to have strong guarantees of the behavior of Blockchain software. These guarantees can be brought by using Formal Methods. Indeed, Blockchain software encompasses many topics of computer science where using Formal Methods techniques and tools are relevant: consensus algorithms to ensure the liveness and the security of the data on the chain, programming languages specifically designed to write Smart Contracts, cryptographic protocols, such as zero-knowledge proofs, used to ensure privacy, etc. This workshop is a forum to identify theoretical and practical approaches of formal methods for Blockchain technology. Topics include, but are not limited to: * Formal models of Blockchain applications or concepts * Formal methods for consensus protocols * Formal methods for Blockchain-specific cryptographic primitives or protocols * Design and implementation of Smart Contract languages * Verification of Smart Contracts -------------------------------- -------------------------------- SUBMISSION -------------------------------- Submit original manuscripts (not published or considered elsewhere) with a maximum of twelve pages (full papers), six pages (short papers), and two pages (extended abstract) describing new and emerging ideas or summarizing existing work). Each paper should include a title and the name and affiliation of each author. Authors of selected extended-abstracts are invited to give a short lightning talk. At least one author of an accepted paper is expected to present the paper at the workshop as a registered participant. Submission link: https://easychair.org/conferences/?conf=fmbc2020 -------------------------------- -------------------------------- PROCEEDINGS -------------------------------- All submissions will be peer-reviewed by at least three members of the program committee for quality and relevance. Accepted regular papers (full and short papers) will be included in the workshop proceedings. -------------------------------- -------------------------------- INVITED SPEAKER -------------------------------- Grigore Rosu, Professor at University of Illinois at Urbana-Champaign, USA and Founder of Runtime Verification http://fsl.cs.illinois.edu/index.php/Grigore_Rosu https://runtimeverification.com/ -------------------------------- -------------------------------- PROGRAM COMMITTEE -------------------------------- PC CO-CHAIRS * Bruno Bernardo (Nomadic Labs, France) (bruno(a)nomadic-labs.com) * Diego Marmsoler (University of Exeter, UK) (D.Marmsoler(a)exeter.ac.uk) PC MEMBERS * Wolfgang Ahrendt (Chalmers University of Technology, Sweden) * Lacramioara Astefanoei (Nomadic Labs, France) * Massimo Bartoletti (University of Cagliari, Italy) * Bernhard Beckert (Karlsruhe Institute of Technology, Germany) * Achim Brucker (University of Exeter, UK) * Silvia Crafa (Universita di Padova, Italy) * Zaynah Dargaye (Nomadic Labs, France) * Jérémie Decouchant (University of Luxembourg, Luxembourg) * Ansgar Fehnker (University of Twente, Netherlands) * Georges Gonthier (Inria, France) * Florian Kammueller (Middlesex University London, UK) * Maurice Herlihy (Brown University, USA) * Igor Konnov (Informal, Austria) * Andreas Lochbihler (Digital Asset, Switzerland) * Anastasia Mavridou (NASA Ames, USA) * Simão Melo de Sousa (Universidade da Beira Interior, Portugal) * Karl Palmskog (KTH, Sweden) * Vincent Rahli (University of Birmingham, UK) * Andreas Rossberg (Dfinity Foundation, Germany) * Claudio Russo (Dfinity Foundation, USA) * César Sanchez (Imdea, Spain) * Clara Schneidewind (TU Wien, Austria) * Ilya Sergey (Yale-NUS College/NUS, Singapore) * Bas Spitters (Aarhus University/Concordium, Denmark) * Mark Staples (CSIRO Data61, Australia) * Meng Sun (Peking University, China) * Simon Thompson (University of Kent, UK) * Philip Wadler (University of Edinburgh / IOHK, UK) (Note: Additional PC members may be added in the coming weeks.)

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GSoC 2020
by Guillem Bartrina Moreno 25 Mar '20

25 Mar '20

Hello everybody! My name is Guillem and I'm a 3rd year computer science student from Spain. This semester I'm taking Functional Programming, where we use Haskell as base language, and Compilers courses. I really love Haskell and the functional programming paradigm in general, so when I saw it in the GSoC list I got really excited. The idea that caught my attention, that is related to both Haskell and Compilers, is: - Update stylish-haskell to use ghc-lib-parser I have a medium understanding of Haskell and I would like to know if this idea is suitable for me. I've tried to start reading the source code and I have understood the most part. I will proceed to write my proposal in the next few days if all goes well. All thoughts are welcome! Thanks for your attention, -- Guillem Bartrina Moreno

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Munich Virtual Haskell Meeting, 2020-03-25 @ 19:30
by Leah Neukirchen 23 Mar '20

23 Mar '20

Dear all, This week, our monthly Munich Haskell Meeting will take place again on Wednesday, March 25. **Due to curfew in Bavaria, this meeting will take place online!** For details see here: http://muenchen.haskell.bayern/dates.html A Google Meet link to join the room will be provided on Wednesday. Everybody is welcome, especially the Haskellers from Bavaria that do not usually come to our Munich meetings due to travel distance! cu, -- Leah Neukirchen <leah(a)vuxu.org> https://leahneukirchen.org/

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Strange error when cabal installing.
by David Banas 23 Mar '20

23 Mar '20

After installing the *Haskell Platform* on my Windows 10 machine, I attempted to cabal install something and got: cabal.exe: The package has a './configure' script. If you are on Windows, This requires a Unix compatibility toolchain such as MinGW+MSYS or Cygwin. If you are not on Windows, ensure that an 'sh' command is discoverable in your path. I've confirmed that the following line is in my cabal config file: extra-prog-path: C:\Program Files\Haskell Platform\8.6.5\msys\usr\bin, C:\Users\capnf\AppData\Roaming\cabal\bin and that there *is* a *sh.exe* file in the "C:\Program Files\Haskell Platform\8.6.5\msys\usr\bin" directory. What am I missing? Thanks, -db

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Multiple Research Positions (3 Doctoral, 5 Post-doctoral) on AI Verification
by Ekaterina Komendantskaya 21 Mar '20

21 Mar '20

AI Secure and Explainable by Construction: Multiple Research Positions (3 Doctoral, 5 Post-doctoral) available at Heriot-Watt, Edinburgh and Strathclyde Universities, Scotland, UK. Start date: 1 September 2020; End date: 30 August 2023 Postdoctoral Salary Scale: £31,866 to £40,322 per annum PhD funding: covering PhD fees and stipend for 3.5 years Closing date for Postdoctoral applications: 1 June 2020 We encourage interested applicants to contact us informally ASAP. The project has sufficient flexibility to mitigate the effect of COVID-19, i.e. by accommodating later start date and remote working. The project spans several subjects: type theory, automated and interactive theorem proving, security, AI and machine learning, autonomous systems, natural language processing and generation, legal aspects of AI. It will cover two main application areas: autonomous cars and chatbots, drawing from expertise and infrastructure provided by industrial partners working in these two areas. The project has a significant international span, with 12 partners from Academia and Industry in Europe (France, Germany, Israel, the Netherlands, Norway) and the US. Researchers joining this project will have excellent opportunities to travel to international conferences, organise scientific events, spend time with industrial partners, collaborate with academic leaders in the field, develop their own research profiles as well as gain experience in other AI and CS disciplines. For further information, and instructions how to apply, please visit: http://laiv.uk/index.php/vacancies/ Ekaterina Komendantskaya: http://www.macs.hw.ac.uk/~ek19/ Robert Atkey: https://bentnib.org/ David Aspinall: https://homepages.inf.ed.ac.uk/da/ Burkard Schafer: https://www.law.ed.ac.uk/people/professor-burkhard-schafer Verena Rieser: https://sites.google.com/site/verenateresarieser/

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2 PhD Positions in the Safety and Security of Advanced Systems Group (University of Exeter, UK Deadline 2020-05-01)
by Achim D. Brucker 20 Mar '20

20 Mar '20

Two fully funded PhD scholarships for EU/UK applicants are available in the Security and Trust of Advanced Systems Group [1] (Prof. Achim Brucker [2] and Dr. Diego Marmsoler [3]) at the Department of Computer Science of the University of Exeter, UK [4]. We are looking for enthusiastic and outstanding Computer Science or Mathematics students with a strong background in some of the following topics: - safety or security of (software) systems, - formal modelling or formal reasoning/verification, - program analysis or program verification, - language-based security - semantics of programming languages, - theorem proving, model checking, - cryptographic protocols, - distributed systems (e.g., blockchain), - specification-based testing, and - design and implementation of security architectures. This award provides annual funding to cover UK/EU tuition fees and a tax-free stipend. For students who pay UK/EU tuition fees the award will cover the tuition fees in full, plus at least £15,009 per year tax-free stipend. The studentship will be awarded on the basis of merit for 3.5 years of full-time study. For more details, please consult the official advertisement: http://www.exeter.ac.uk/studying/funding/award/?id=3887 The closing date for applications is midnight on 1 May 2020. Project-specific queries should be directed to the supervisors, Prof Achim Brucker (A.Brucker(a)exeter.ac.uk) or Dr Diego Marmsoler (D.Marmsoler(a)exeter.ac.uk) Best, Achim and Diego [1] http://emps.exeter.ac.uk/computer-science/research/cyber-security/ [2] https://www.brucker.uk/ [3] https://marmsoler.com/ [4] http://emps.exeter.ac.uk/computer-science/ -- Prof. Achim Brucker | https://www.brucker.ch | https://logicalhacking.com/blog *We are hiring:* * Lecturer (Assistant Professor) - Deadline 2020-04-08: https://www.jobs.ac.uk/job/BZH668/lecturer-in-computer-science-education-an… * Two PhD Studentships (EU/UK Tuition Fees) - Deadline 2020-05-01: http://www.exeter.ac.uk/studying/funding/award/?id=3887

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Open Position: Lecturer in Computer Science (Exeter, Deadline 2020-04-08)
by Achim D. Brucker 20 Mar '20

20 Mar '20

Open Position: Lecturer in Computer Science (Exeter, Deadline 2020-04-08) As part of the expansion of the Department of Computer Science at the University of Exeter [1], we are recruiting for a Lecturer in Cybersecurity. The lecturer will be part of the newly formed Security and Trust of Advanced Systems Group [2]. We are looking for a candidate with an outstanding research record in any area related to cyber security (information security) such as (but not limited to): - access control - usable security - software/application security - formal methods for security - language-based security/privacy - secure programming - information flow - security protocols - network security - security of distributes systems - human aspects of security - hardware security - security economics - security-by-design - applied cryptography - privacy-enhancing technologies - threat hunting, security analytics - threat modelling - forensics, reverse engineering - trustworthy AI/ML - security/penetration testing You will have a PhD or equivalent in Cybersecurity, Computer Science, Mathematics, Engineering or a related area. Please refer to the job description for full details. We understand **security and safety entangled concepts**: in most modern systems one cannot be achieved without the other. Hence, we encourage also candidates working in related domains such as **safety, dependability, resilience, or reliability** to apply. Please apply by 8th of April 2020! See the full announcement and application details at https://jobs.exeter.ac.uk/hrpr_webrecruitment/wrd/run/ETREC107GF.open?VACAN… We are happy to do online/remote interviews. Feel free to contact me for informal inquiries about the post. Best, Achim [1] https://www.exeter.ac.uk/computer-science/ [2] https://emps.exeter.ac.uk/computer-science/research/cyber-security/ -- Prof. Achim Brucker | https://www.brucker.ch | https://logicalhacking.com/blog *We are hiring:* * Lecturer (Assistant Professor) - Deadline 2020-04-08: https://www.jobs.ac.uk/job/BZH668/lecturer-in-computer-science-education-an… * Two PhD Studentships (EU/UK Tuition Fees) - Deadline 2020-05-01: http://www.exeter.ac.uk/studying/funding/award/?id=3887

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Help with async library and killing child processes
by Michael Hull 20 Mar '20

20 Mar '20

Hi, I am currently learning Haskell, and really enjoying it, thankyou to the community for this well considered language. I have started using the async library, and I can't quite figure out some of the documentation, and I wonder if someone could help. https://hackage.haskell.org/package/async-2.2.2/docs/Control-Concurrent-Asy… Makes the comment that: "This is a useful variant of async <https://hackage.haskell.org/package/async-2.2.2/docs/Control-Concurrent-Asy…> that ensures an Async is never left running unintentionally." However, I can't see how I would use this. To make the example more concrete, I have a function that looks like this: runNodeHwBridgeUdp :: NodeHwInterface -> NodeHwUdpConfig-> IO() runNodeHwBridgeUdp (NodeHwInterface l0up l0down) config = do putStrLn "Starting Node bridge" -- Launch all the subprocesses: t0 <- async $ (runMsgUpReader hwBridgeSharedData l0up) t1 <- async $ (evalStateT (runUDPWriter hwBridgeSharedData) (initialUdpDispatchData timeUs) ) t2 <- async $ (runUDPReader hwBridgeSharedData l0down) putStrLn "Created child processes. Waiting...." (a, is_exception) <- waitAnyCatchCancel [t0, t1, t2] case is_exception of Right _ -> do error "SHOULD NOT GET HERE" Left exception -> do case (fromException exception) of Just (ex :: HwDestroyException) -> do putStrLn $ "BRIDGE ENDING: >>>> GOOD: SHUTDOWN: " ++ show exception Nothing -> do throwIO exception return () This process launches 3 child processes, and then waits on them. I launch this function as an async-process, and it would be really helpful if when I "cancel"ed it, it would also also cancelled the children, but I don't understand how I would structure that... t0 <- withAsync $ (runMsgUpReader hwBridgeSharedData l0up) $ \async -> do ???? t1 <- withAsync $ (evalStateT (runUDPWriter hwBridgeSharedData) (initialUdpDispatchData timeUs) ) $ \async -> do ???? t2 <- async $ (runUDPReader hwBridgeSharedData l0down) $ \async -> do ???? I feel like I must be missing something here. I'd appreciate any input; many thanks for your time, Mike

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Re: [Haskell-cafe] Adding Content-Addressable Storage to GHC
by Michal J Gajda 19 Mar '20

19 Mar '20

Great idea! We already have syntax for package imports: ``` import "bytestring" Data.ByteString ``` Source plugin could probably pull and build package by CAS: ``` import "CAS_6ffeacff768590" Data.ByteString ``` That would reuse existing syntax without confusion. And without inconvenience of having to import expressions one by one. Or declaring their types. One could even add CAS hashes to Hackage db. Probably the source plugin can add `-package` parameters with GHC_OPTIONS? On the expression side, it seems easy to use Generics to derive hashable for `Exp`, given a *particular compiler version*. Warning is, that one needs to be more careful when the `Exp`ression type changes. -- Cheers Michal

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Adding Content-Addressable Storage to GHC
by Chris Done 18 Mar '20

18 Mar '20

Hi all, Is there any effort or designs ongoing to add CAS (content-addressable storage) to GHC, as in Unison? < https://www.unisonweb.org/docs/tour/> == The idea == The summary of the idea is simply that top-level declarations can be addressed by a hash of their contents. Recursive definitions are transformed into the worker/wrapper to eliminate the self-referencing issue of hashing. == Why I want this == There are lots of advantages to this, but the one that excites me the most is that we can move to running tests, especially property tests, at compile-time. The main downside to running tests at compile-time, as seen done with template-haskell is that you will re-run tests every time the module is recompiled, making your dev cycle slower. However, if your tests are keyed upon CAS hashes, then those hashes are only invalidated when individual declarations actually change. This means the re-running of tests becomes granular at the declaration-level. When a single test completes, either successfully or not, you can cache the result and lookup the result next time, using e.g. the SHA512 of the expression evaluated. Therefore you could change a single function in a library and it would only re-run the tests that are actually affected, rather than running all the tests in the whole module, and rather than the more typical approach which is running ALL tests in a test suite just because one thing changed. If you can couple tests with code then you can avoid the decoupling of code from the tests. == Implementation approaches == There are various ways to implement this with varying degrees of satisfaction: 1. Use TH: reify declarations, inspect the AST, and produce a SHA512. Use ambient values such as the GHC version, instances in scope, extensions, ghc options, etc. With TH, I'm confident that you can only achieve an imperfect hash because I doubt that all information is available to TH. Names that come from external packages could be treated as CAS'd at the scope of the package's installed hash. Ideally, you could have granularity into other packages. But it's not a necessity if you just want caching for your current development package. 2. Use a source plugin. A source plugin is already capable of accessing all GHC context information, so this might lead to more of a perfect hash. 3. Add it to GHC directly. Exposing a `expressionSHA512 :: Exp -> ByteString` could be one imaginary way to access this information. With such a function you could implement caching of fine-grained tests. A related discussion is the deterministic builds: https://gitlab.haskell.org/ghc/ghc/wikis/deterministic-builds Anyone else exploring this? Cheers, Chris

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