March 2021 - Haskell-Cafe

Announcing `passveil` 0.0.1.0
by raichoo 08 Mar '21

08 Mar '21

Hi everyone, My company antei (https://antei.de) has developed a password manager for our internal usage and we have decided to open source it. We drew a lot of inspiration from the well established `password-store`. It's build in Haskell and uses `darcs` for versioning the password store. We have chosen `darcs` because of its powerful merging capabilities which turned out to be useful for our use case. Apart from that, we have implemented a trust system, that can be used to transfer knowledge of a password to other people having access to the store, so we do not have to rely on transmitting sensitive data via insecure channels (https://sysadminotaur.devolutions.net/30-vault) Please note that `passveil` is in an early state and has only been tested and used internally. We strongly believe in open source and making our tools available to others and are constantly working on improving our code and want share our progress with everyone. Check out: https://passveil.antei.de for more information. Kind regards, raichoo

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Profiling analyzing ghc compilation
by Martin Heuschober 05 Mar '21

05 Mar '21

Hi, Is there a way to profile (time/space) GHC compilation itself, I'd be interested in what compilation steps in compiling my project take long and how much RAM it uses/why it uses so much RAM, so I can identify what to rewrite, remove, and split to get a leaner build. Thanks, Martin PS.: I hope this is the right place to ask this.

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Haskell.org Call For Nominations
by Rebecca Skinner 05 Mar '21

05 Mar '21

Dear Haskellers, As you may know, Emily Pillmore has recently stepped down from her role on the Haskell.org committee as she focuses full time on her new role as the CTO of the Haskell Foundation. We are currently seeking nominations for anyone interested in filling her vacated seat on the committee. The term for this seat will end in October of 2021, so it will be a good opportunity for anyone who is interested in serving for a short time, perhaps to get a better idea of whether they would like to be re-nominated for a full term at the end of the year. The role is about setting policy, providing direction/guidance for Haskell.org infrastructure, planning for the long term, and being fiscally responsible with the Haskell.org funds and donations. As overseers for policy regarding the open source side of Haskell, committee members must also be able to set aside personal or business related bias and make decisions with the good of the open source Haskell community in mind. For more information about the haskell committee please visit https://www.haskell.org/haskell-org-committee/ To nominate yourself, please send an email to committee(a)haskell.org no later than 12 March 2021. Q: If selected for this role, will I serve a normal 3-year term? A: No, you will serve the remainder of the term for the seat, which will end in October of 2021. Q: If I was nominated for a seat during the 2021 election and was not selected, am I eligible for re-nomination? A: We had a number of great candidates for the recent election and we would welcome anyone who was not selected to re-nominate themselves for this seat. Q: If selected, am I eligible for re-nomination at the end of the year? A: Yes, if you are selected and serve you may be re-nominated for a full 2022-2025 term. Q: Who can be nominated to serve on the committee? A: Anyone who has something to contribute. Committee members do not need to be deep technical Haskell experts. Instead we look for enthusiasm towards improving the Haskell community. We aim to represent the different facets of the community. We aim to be diverse in terms of industry or research, and in terms of gender, race and location. Q: What should I include in my nomination? A: Tell us a bit about who you are, and how you think you can help. Feel free to include anything that you think will help us make a better decision. Q: What is involved in membership? A: Being a member of the committee does not necessarily require a significant amount of time, but committee members should aim to be responsive during discussions when the committee is called upon to make a decision. For more information, or any other questions, please reach out to the committee by email. - Rebecca Skinner on behalf of the Haskell.org Committee

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Re: [Haskell-cafe] naturally, length :: a -> Int
by Olaf Klinke 05 Mar '21

05 Mar '21

> Date: Thu, 4 Mar 2021 11:36:14 +0100 > From: Ben Franksen <ben.franksen(a)online.de> > To: haskell-cafe(a)haskell.org > Subject: Re: [Haskell-cafe] naturally, length :: a -> Int > Message-ID: <s1qd6u$l43$1(a)ciao.gmane.io> > Content-Type: text/plain; charset=utf-8 > > Am 03.03.21 um 16:17 schrieb Olaf Klinke: > > Which bugs can be caught at compile-time by having length return > > natural numbers? Regarding space, Int instead of Word only wastes the > > sign bit, doesn't it? > > > > I like the idea that Johannes Waldmann and Jaro Reinders brought up: > > Why is length :: Foldable a => a -> Int so convenient? Short answer: > > Because of "affine" things like `availableSpace - length xs'. > > > > There are indeed two types involved here, as the foundation package > > points out: relative offsets (like a tangent space?) and absolute > > counts. Think of NominalDiffTime versus UTCTime, or the two > > interpretations of vectors as points/movements in space. > > > > In this light one could regard the current length as > > "the relative offset of the end of the list" which can readily be > > subtracted from another relative offset. In mathematical terms: Int the > > free group over the monoid of cardinal lengths. > > Hm, interesting point. > > If we do embrace that viewpoint, then I'd say we should go all the way > and interpret indices modulo (non-negative) structure size! This makes > (safe) indexing total (for non-empty structures) and allows things like > xs !! (-1) == last xs as in Perl and some other languages. Unsafe > indexing (as in the vector package) could remain as is for performance > critical code. > > Cheers > Ben I like Haskell particularly for not being like Matlab, where virtually any well-bracketed indexing syntax does produce a result, but not necessarily what you intended or expected. Besides, for some structures length is expensive but index is not so much, so I wonder whether one can modulo-index into a lazy container without evaluating its entire spine. I just wanted to understand/justify why Int is so convenient, and the Time-DiffTime analogy sprang to mind. Following the free group route, one immediately sees that there is an embedding from cardinalities to offsets, but no inverse. We could, of course, bring other categories into the picture such as ordered sets. Then there is an embedding-projection pair between Int and Natural, where all Ints < 0 are mapped to 0. The base functions such as take and drop adhere to this interpretation. Olaf

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Serious bug with Natural in GHC 9.0.1
by Sylvain Henry 04 Mar '21

04 Mar '21

Hi Café, I've made a mistake while implementing constant folding for Natural numbers in GHC 9.0.1 that hasn't been caught before the release. It's a rather serious bug as any number converted into `Natural` with `fromIntegral` can be truncated to Word range if a bogus rule is triggered (see #19345 and #19411 for more details). It is already fixed in HEAD and the fix will be present in GHC 9.0.2 which should be released soon. In the meantime you can check if the rule is triggered with `-ddump-rule-firings`. If it shows that the following rule has fired, then your code may be badly modified: |Rule fired: fromIntegral/Int->Natural (GHC.Real)| (the issue is that despite its name the rule isn't correctly constrained to convert Ints into Natural, but any numeric type...). Sorry about that! Sylvain #19345: https://gitlab.haskell.org/ghc/ghc/-/issues/19345 #19411: https://gitlab.haskell.org/ghc/ghc/-/issues/19411

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naturally, length :: a -> Int
by Johannes Waldmann 04 Mar '21

04 Mar '21

Dear Cafe - let's fight Int. In a lot of code I write (for research, teaching, production), a lot of numbers are in fact natural numbers - because I am counting (e.g., number of elements in a collection) or pointing into what I just counted (e.g., Data.Set.elemAt). But Haskell's "most natural" type is - Int. At least that's my impression from current usage in libraries and teaching examples (see functions length, replicate, ... ). I've developed a horror of reading and writing "length something :: Int". As I will be teaching an introductory class on FP soon, I am looking for ways to handle this. One option is presented in Bird/Gibbons: Algorithm Design with Haskell, which has "type Nat = Int" on page 6. Actually, that's the very first code example that appears in the book! The footnote there refers to a remark in Data.Word that has since been dropped? Now there is Numeric.Natural, (cf. https://mail.haskell.org/pipermail/libraries/2014-November/024203.html ) and numeric literals are already overloaded, so we can just use that? Well, yes and no - we still have to write a type conversion each time we use some library function that insists on Int, or, write cumbersome "genericLength". Also (but that is the lesser concern), Numeric.Natural is for arbitrary-length numbers (corresponding to Integer), while I might sometimes know that numbers are representable in a machine word, and I don't want to pay for the implied pattern match (data Natural = NatS Word | NatJ BigNat). I am willing to pay for underflow checks (on subtraction), and for overflow checks (if there's an upper bound). If I want to live risky (no checks) I could use Data.Word. So, what do you do? (Yes, Peano numerals ...) Or, how do we convince ourselves (and our students) of keeping the current status? NB: here is another practical argument for Natural (from production code, an auto-grading system for student homework) We use datatype-generic parsers heavily. For data Foo = Foo { ... :: Nat ... }, bad input will be rejected by the parser already, and I need no extra checks later on. Less code! I sometimes even use "Pos(itive)". That's all fine and dandy - until I call some library function... - J.W.

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aeson: instance FromJSON IntMap
by Olaf Klinke 03 Mar '21

03 Mar '21

Dear Cafe, why is Aeson's instance FromJSON IntMap so different from the instance of Map? Apparently the Map instance expects an Object (the dictionary) while the IntMap instance [1] is implemented using IntMap.fromList, so it expects an array. I can of course decode the JSON as (Map Int) and then use IntMap.fromAscList . Map.assocs but how efficient is that? And it also relies on Map.assocs producing the list in the order expected by fromAscList which (unlikely) could be broken in a future version of containers. Thanks Olaf [1] https://hackage.haskell.org/package/aeson-1.5.6.0/docs/src/Data.Aeson.Types…

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International Conference on Applied Data Science and Intelligence - (ADSI 2021) Prague
by matteo＠confscience.com 03 Mar '21

03 Mar '21

Call for papers ************************************************* International Conference on Applied Data Science and Intelligence - (ADSI 2021) Prague- Czech Republic, October 14-15, 2021 https://confscience.com/adsi/ Submission deadline: April 1, 2021 All papers accepted in ADSI 2021 will be published in Springer CCIS (Communications in Computer and Information Science). CCIS is abstracted/indexed in Scopus, SCImago, EI-Compendex, Mathematical Reviews, DBLP, Google Scholar, and Thomson Reuters Conference Proceedings Citation (Former ISI Proceedings) *************************************************************************** IMPORTANT DATES: - Paper Submission: April 1, 2021 - Acceptance Notification: July 1, 2021 - Final Manuscript Due: September 1, 2021 *************************************************************************** The ADSI 2021 conference will be held in Conjunction with: International Conference on Recent Theories and Applications in Transportation and Mobility (RTATM 2021) International Conference on Informatics Revolution for Smarter Healthcare (IRSH 2021) *************************************************************************** TOPICS: Authors are invited to submit their original papers to address the topics of the conference, including but not limited to: FUNDAMENTALS AND THEORIES - Theoretical Models - Spatial and temporal multi-models - Multi-dimensional data - Data acquisition and pre-processing - Data inference - Data Classification and Taxonomy - Data Metrics - New approaches for collaboration and competition - Self-organization, self-healing, fault-tolerance approaches - Spatial reasoning - Context awareness - Intelligent mobility - New approaches to supervised and unsupervised learning - New approaches for security, privacy, trust, and ethics in data science - Real-time data analytics - Multi-Agent Systems for data science - Distributed data analytics - Data authenticity - New theories and approaches for Deep learning - New approaches for Business Intelligence - Fuzzy logic - Decision trees - Support vector machines - Evolutionary computation - Statistical methods - Collaborative filtering - Data engineering - Content mining - Indexing schemes - Information retrieval - Metadata use and management INTELLIGENT DATA PROCESSING AND ANALYTICS - Multi-level data processing - Data analytics optimization - Smart data mining - Machine Learning - Deep Learning - Bio-Inspired Computing - Secure data analytics - Privacy in data analytics - Trust in Big Data - Business intelligence - Visualization Analytics - Intelligence as a Service (IaaS) - Data Science as a Service (DSaaS) - Natural Language Processing - Signal Processing - Simulation and Modeling - Data-Intensive Computing SYSTEMS AND INFRASTRUCTURES - Data storage infrastructure - Data warehouses - Data Query and Indexing Technologies - Software Defined Infrastructures - Software Defined Networks (SDN) - Distributed data systems - Smart grid computing - Intelligent data management - Big Data computing - Smart data networking - Internet of Things - Cyber Physical Systems - Blockchain - Fog and Edge intelligence - Parallel Computing systems - Open Source systems for data science - Embedded intelligence - Embedded data science - In-Memory computing - Intelligent drones - Internet of Drones - Real-time data acquisition systems APPLICATIONS - Intelligent Hazard management - Intelligent data science in healthcare - Intelligent data science in farming - Intelligent data science in Oil and Gas - Smart logistics - Intelligent data science in transportation - Intelligent data science in surveillance - Xtech (Fintech, Agritech, etc.) - Intelligent drones - Digital transformation - Bioinformatics - Marketing - Social Science - E-learning and E-services *************************************************************************** OUTSTANDING PAPERS: Based on the peer review scores as well as the presentations at the conference, the authors of outstanding papers will be invited to extend their works for a potential publication in journals special issues with high impact factors. *************************************************************************** PAPER SUBMISSION: Papers must be submitted electronically as PDF files via easychair (https://easychair.org/conferences/?conf=adsi2021) All papers will be peer reviewed. Length of Full papers: 12-15 pages long (written in the LNCS/CCIS one-column page format, 400 words per page) Length of Short papers: less than 12 pages For more information, please refer to the conference website: https://confscience.com/adsi/ *************************************************************************** CONTACT For more information, please send an email to info-adsi(a)confscience.com

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International Conference on Informatics Revolution for Smarter Healthcare (IRSH 2021) Prague
by matteo＠confscience.com 03 Mar '21

03 Mar '21

Call for papers ************************************************* International Conference on Informatics Revolution for Smarter Healthcare (IRSH 2021) Prague- Czech Republic, October 14-15, 2021 https://confscience.com/irsh/ Submission deadline: April 1, 2021 All papers accepted in IRSH 2021 will be published in Springer CCIS (Communications in Computer and Information Science). CCIS is abstracted/indexed in Scopus, SCImago, EI-Compendex, Mathematical Reviews, DBLP, Google Scholar, and Thomson Reuters Conference Proceedings Citation (Former ISI Proceedings) *************************************************************************** IMPORTANT DATES: - Paper Submission: April 1, 2021 - Acceptance Notification: July 1, 2021 - Final Manuscript Due: September 1, 2021 *************************************************************************** The IRSH 2021 conference will be held in Conjunction with: International Conference on Applied Data Science and Intelligence (ADSI 2021) International Conference on Recent Theories and Applications in Transportation and Mobility - (RTATM 2021) *************************************************************************** TOPICS: Authors are invited to submit their original papers to address the topics of the conference, including but not limited to: FUNDAMENTALS AND THEORIES - Interoperability and Data Integration - Confidentiality and Data Security - Data protection - Data Sharing - Security, Privacy, and Trust - Emergent healthcare standards - Emergent healthcare architectures - ICT, Ageing and Disability - Physiological and behavioural modelling - Pandemic and disease modeling - Usability and user experience of medical devices - Human behaviour - Clinical investigation regulatory frameworks - Integrated healthcare approaches - eHealth data standards and interoperability (e.g. HL7/FHIR) - Databases and data warehousing - Big Data and Open Data for healthcare - Design and Development of Methodologies for Healthcare - Emergent Communication Technologies - Real-time interaction theories - Emergent Technologies for Ambient Assisted Living - User Interface Design for healthcare - Sustainability - New approaches for accuracy and effectiveness - Data mining and bioinformatics - Enhanced living environments - Analysis and evaluation of healthcare systems INTELLIGENT HEALTHCARE - Pattern recognition and Machine - Learning for healthcare - Cognitive Informatics - Big Data in Healthcare - Wellbeing Informatics - Data Mining and Data Analytics - Data Visualization - Smart environments - Smart Ambient Assisted Living - Intelligent healthcare solutions - Agent-based solutions for healthcare - Collaboration systems - Intelligent Electronic Health Records - Internet of Things for healthcare - Cyber-Physical Systems for healthcare - Ambient Computing and Reasoning - Context Awareness - Smart devices for eldercare - Autonomy and active ageing - Emergent technologies for intelligent Computer Vision - Service production and delivery - Gamification - Multi-modal interaction - Computer-aided detection and diagnosis - Crowdsourcing for smarted healthcare SERVICES, SYSTEMS, AND INFRASTRUCTURES - Emergent healthcare services - Pervasive health systems and services - Remote healthcare management - Emergent healthcare infrastructure - Industry Revolution 4.0 for healthcare - eHealth - Electronic health records - Assistive technologies - Disease surveillance and patient monitoring systems - Prevention and detection systems - Home monitoring - Healthcare management systems - ICT-based therapeutic systems - ICT-based rehabilitation technologies - Wearable health informatics - Emergent technologies for data analytics - Ambient Assisted Leaving (AAL) - Decision Support Systems - Emergent Technologies for Remote AAL Monitoring - Emergent Technologies and Accessibility - 5G for healthcare - Healthcare supply chain and logistics - Wireless Body Networks - Telemedicine and mobile telemedicine - Mobile Systems - Software Defined infrastructures - Patient empowerment systems - Smart technology for remote patient visits - Biosensors - Medical devices APPLICATIONS - eHealth applications - Application of health informatics in clinical cases - Mobile technologies for healthcare applications - Software Systems in healthcare - Social networking and healthcare - Case Studies - Personalization and patient experience - AR and VR applications - Patient billing - Accounting systems - Personnel and payroll - Materials management - Voice recognition systems - Asset management solutions - Disease management - Feedback integration - Clinical software - Crowd-computing applications - Future directions - Drone-based solutions - Software Defined Networks for healthcare *************************************************************************** OUTSTANDING PAPERS: Based on the peer review scores as well as the presentations at the conference, the authors of outstanding papers will be invited to extend their works for a potential publication in journals special issues with high impact factors. *************************************************************************** PAPER SUBMISSION: Papers must be submitted electronically as PDF files via easychair (https://easychair.org/conferences/?conf=irsh2021) All papers will be peer reviewed. Length of Full papers: 12-15 pages long (written in the LNCS/CCIS one-column page format, 400 words per page) Length of Short papers: less than 12 pages For more information, please refer to the conference website: https://confscience.com/irsh/ *************************************************************************** CONTACT For more information, please send an email to info-irsh(a)confscience.com

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Re: [Haskell-cafe] naturally, length :: a -> Int
by Johannes Waldmann 02 Mar '21

02 Mar '21

Dear Cafe, thanks for ideas and arguments. > [Ben Franksen] I would support a move Int->Word in all libraries > where that makes sense. I find it hard to think of a library where that does NOT make sense... The following is somewhat related but actually orthogonal: I mentioned that numbers often arise as cardinalities (so they are natural, by definition) and serve as pointers. The next step is then: pointer type safety. Vincent Hanquez' Foundation https://hackage.haskell.org/package/foundation-0.0.25 defines class (IsList c, Item c ~ Element c) => Collection c where length :: c -> CountOf (Element c) class ( ... Collection c) => Sequential c where take :: CountOf (Element c) -> c -> c with newtype CountOf ty (and there's also newtype Offset ty) I tend to agree. The phantom type argument for CountOf would catch errors like adding the number of students to the number of exercises (in my application). (Well and the next step after that would be to have the size of the collection in the (dependent) type as well.) Current implementation is newtype CountOf ty = CountOf Int and the author adds (and that was also the point I was making) "Int is a terrible backing type which is hard to get away from, considering that GHC/Haskell are mostly using this for [counting and] offset. Trying to bring some sanity by a lightweight wrapping." NB: I found out about this from Michael Snoyman's (very much entertaining, and too much true) https://www.snoyman.com/blog/2020/12/haskell-bad-parts-3/ Best regards, J.W.

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