- Haskell-Cafe - Haskell.org

LFVM-STG Compilation
by james faure 10 May '19

10 May '19

Hello, I want to introduce the STG backend I am currently working on: https://github.com/jfaure/lfvm-stg I'd love to see how much interest there is for this, to receive any comments, and find out if I've missed anything ! The goal is to massively speed up compilation times and generate faster and clearer code, and in that respect I am already quite successful. Llvm is very well suited for encoding a (lazy) functional language, however the evaluation mechanism is very different to ghc's stg, there is notably no continuation passing nor result registers. In LFVM, all non constant let bindings are given an llvm function. I believe this approach is more natural, the llvm more accurately reflects the source code and we get proper stack traces in a debugger. Status: The project is barely a month old, and I'm working to support everything ghc's code generation supports. The STG is heavily based on the one found in ghc and, at this time and as far as I can tell, supports everything except multithreading, a gc and lazy evaluation. The current idea I think is very promising is to use an inferred pi calculus to elegantly implement all 3 missing parts at once. Pi calculus [1] (process calculus) In the STG * Multithreading occurs for arguments of functions with >1 arity * Perfect garbage collection is quite probably possible [2], where allocation creates a new pi name, and its uses are modeled by pi calculus communication * Perfect Lazy evaluation (in the sense that the wrapper and associated wrapped type overhead is coerced away after the first evaluation) is possible in the pi calculus and closely linked the gc model. I intend to make strict evaluation the default, If you want lazy (for MonadFix or infinite lists or whatever), you must request it. [1]: https://en.wikipedia.org/wiki/%CE%A0-calculus [2]: https://www.researchgate.net/publication/228514964_Resources_garbage-collec… James Faure (Discord: J4#0303)

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Need help understanding Ralf Hinze's Lifting Lemma, and its connection to the Transfer Principle
by Brian Merchant 10 May '19

10 May '19

Hi all, I am a student in mathematics exploring alternative ways in which the transfer principle ( https://en.wikipedia.org/wiki/Transfer_principle ) can be proved. I've found a paper by Ralf Hinze which I think is relevant: https://www.cs.ox.ac.uk/ralf.hinze/Lifting.pdf. However, I'd benefit from being able to talk to someone who understands the notation starting section 3 and onwards, as I am very much a Haskell newbie (everything I have learned, has been in the last 4 days, as I try to decipher this paper). Would anyone be willing to have a conversation with me regarding this? Kind regards, Brian

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FHPNC'19 Deadline Extension and 2nd Call for Papers
by Marco Zocca 09 May '19

09 May '19

We are happy to extend the submission deadline to the 2019 ACM SIGPLAN Functional High Performance and Numerical Computing Workshop until Saturday, May 25, 2019, 12 PM AoE ("anywhere on Earth", i.e. UTC-6). Marco Zocca and Dominic Steinitz FHPNC'19 Organizing Committee ================================= 2nd Call for Papers (Extended Abstracts and Full Papers) ACM SIGPLAN Workshop on Functional High-Performance and Numerical Computing (FHPNC), Berlin, August 18, 2019 Satellite event of the 24th ACM SIGPLAN International Conference on Functional Programming (ICFP 2019) 18 - 23 August, 2019 Homepage : https://icfp19.sigplan.org/home/FHPNC-2019#Call-for-Papers The ACM SIGPLAN International Workshop on Functional High-Performance and Numerical Computing aims to bring together researchers and practitioners exploring or employing the use of functional or declarative programming languages or techniques in scientific computing, and specifically in the domains of high-performance computing and numerical programming. The purpose of the meeting is to enable sharing of results, experiences, and novel ideas about how high-level, declarative techniques can help make high-performance, distributed/parallel, or numerically-intensive code dealing with computationally challenging problems easier to write, read, maintain, or portable to new hardware architectures. Areas of interest include, but are not limited to: * relevant compiler technologies * runtime systems (including fault tolerance mechanisms and those supporting distributed or parallel computation) * domain-specific languages (embedded or standalone) * type systems * formal methods * software libraries (e.g. for exact or interval arithmetic). ## Submission details Submissions should fall into one of two categories: * Regular research papers (up to 12 pages) * Extended abstracts (1 - 2 pages) The bibliography will not be counted against the page limits for either category. Regular research papers are expected to present novel and interesting research results, and will be included in the formal proceedings. Extended abstracts should report work in progress that the authors would like to present at the workshop; they will be evaluated primarily for relevance and interest. Extended abstracts will be distributed to workshop attendees but will not be published in the formal proceedings. We welcome submissions from PC members (with the exception of the PC Chair), but these submissions will be held to a higher standard. Submission is handled through the HotCRP site. All submissions should be in portable document format (PDF) and formatted using the ACM SIGPLAN style guidelines. Submissions written with LaTeX are required to use the ‘acmart’ format and the two-column ‘sigplan’ subformat (not to be confused with the one-column ‘acmlarge’ subformat!). Extended Abstracts must be submitted with the label ‘Extended abstract’ clearly in the title. ## Publication The proceedings of FHPNC 2019 will be published in the ACM Digital Library. ## Related links * Author Information and LaTeX templates : http://www.sigplan.org/Resources/Author/ * Attendee Code of Conduct: http://www.sigplan.org/Resources/Policies/CodeOfConduct/

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Invititation to provide feedback on RISC-V ISA Formal Specs
by Rishiyur Nikhil 09 May '19

09 May '19

The RISC-V Foundation (riscv.org) has a task group to develop a Formal Spec for the RISC-V Instruction Set Architecture. The group has been pursuing several approaches: - 3 are written in Haskell - 1 is in SAIL, a DSL with dependent types, intended for ISA specs - 1 is in Kami, a DSL in Coq Most of them are complete enough to boot Linux, i.e., they are not for toy subsets of the ISA. They are expected and intended to become the "official" ISA spec for RISC-V, and to be used in anger, for compliance testing, formal verification of compilers, hardware designs, etc. We would love to get community feedback on these approaches. The following link provides an overview, and links to individual web sites (all on GitHub) for the 5 approaches, and information on how to provide feedback: https://github.com/riscv/ISA_Formal_Spec_Public_Review Thanks very much in advance! Rishiyur Nikhil, Chair, ISA Formal Spec Technical Group

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Announce: Haskell Platform 8.6.5
by Gershom B 08 May '19

08 May '19

On behalf of the Haskell Platform team, I'm happy to announce the release of Haskell Platform 8.6.5 Now available at https://www.haskell.org/platform/ This includes GHC 8.6.5, cabal-install 2.4.1.0, and stack 1.9.3. It is an incremental release over 8.6.3 intended mainly to make available bugfixes for windows in subsequent revisions in the 8.6 series and otherwise leave everything the same. These windows fixes are important, and it is recommended all windows users upgrade to 8.6.5 whether through the platform installer or some other mechanism. For detail on these changes and fixes see https://www.haskell.org/ghc/blog/20190305-ghc-8.6.4-released.html https://www.haskell.org/ghc/blog/20190423-ghc-8.6.5-released.html As with the 8.6.3 release, we are only providing core builds. Further, in 8.6.3 we moved from generic linux installers to recommending users install ghc through ghcup. As discussed in the last announcement, we have now moved to recommending os x users also use ghcup rather than a dedicated binary installer. For more details, please see the 8.6.3 announcement at https://mail.haskell.org/pipermail/haskell-cafe/2018-December/130371.html Happy Haskell Hacking all, Gershom

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how to debug segfaults in ghc-compiled executable?
by Johannes Waldmann 08 May '19

08 May '19

Dear Cafe, I keep getting spurious segfaults from a dynamically linked executable compiled by ghc. In dmesg: [402186.145258] pure-matchbox:w[25362]: segfault at 7f98644a5c00 ip 00000000017ab65e sp 00007f98377f9988 error 4 [402186.145262] Code: b8 0a 7e 77 01 48 83 ec 08 48 89 df 48 89 c3 31 c0 ff d3 48 83 c4 08 48 8b 1c 25 50 90 a7 01 48 89 c1 48 6b c9 18 48 83 c1 10 <48> 83 3c 0b 00 74 30 48 8b 1c 25 50 90 a7 01 48 6b c0 18 48 83 c0 How can I find out what part of the program this refers to? The error might be related to external libraries (used by hmatrix-glpk) but I don't know how to verify this. When I look at the output of `nm´ for this executable, I am not seeing any address like 00017ab65e. I do not have a concrete reproducible test case, but the bug happens statistically (say, in one out of 1000 runs). - J.

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Journal of Functional Programming - Call for PhD Abstracts
by Graham Hutton 08 May '19

08 May '19

Dear all, If you or one of your students recently completed a PhD in the area of functional programming, please submit the dissertation abstract for publication in JFP: simple process, no refereeing, open access, deadline 31st May 2019. Please share! Best wishes, Graham Hutton ============================================================ CALL FOR PHD ABSTRACTS Journal of Functional Programming Deadline: 31st May 2019 http://tinyurl.com/jfp-phd-abstracts ============================================================ PREAMBLE: Many students complete PhDs in functional programming each year. As a service to the community, twice per year the Journal of Functional Programming publishes the abstracts from PhD dissertations completed during the previous year. The abstracts are made freely available on the JFP website, i.e. not behind any paywall. They do not require any transfer of copyright, merely a license from the author. A dissertation is eligible for inclusion if parts of it have or could have appeared in JFP, that is, if it is in the general area of functional programming. The abstracts are not reviewed. Please submit dissertation abstracts according to the instructions below. We welcome submissions from both the PhD student and PhD advisor/supervisor although we encourage them to coordinate. ============================================================ SUBMISSION: Please submit the following information to Graham Hutton <graham.hutton(a)nottingham.ac.uk> by 31st May 2019: o Dissertation title: (including any subtitle) o Student: (full name) o Awarding institution: (full name and country) o Date of PhD award: (month and year; depending on the institution, this may be the date of the viva, corrections being approved, graduation ceremony, or otherwise) o Advisor/supervisor: (full names) o Dissertation URL: (please provide a permanently accessible link to the dissertation if you have one, such as to an institutional repository or other public archive; links to personal web pages should be considered a last resort) o Dissertation abstract: (plain text, maximum 350 words; you may use \emph{...} for emphasis, but we prefer no other markup or formatting; if your original abstract exceeds the word limit, please submit an abridged version within the limit) Please do not submit a copy of the dissertation itself, as this is not required. JFP reserves the right to decline to publish abstracts that are not deemed appropriate. ============================================================ PHD ABSTRACT EDITOR: Graham Hutton School of Computer Science University of Nottingham Nottingham NG8 1BB United Kingdom ============================================================ This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please contact the sender and delete the email and attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. Email communications with the University of Nottingham may be monitored where permitted by law.

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[TFPIE'19] Final call for papers: Trends in Functional Programming in Education 2019, 11 June 2019, Vancouver, BC, CA
by Peter Achten 08 May '19

08 May '19

TFPIE 2019 Call for papers http://www.staff.science.uu.nl/~hage0101/tfpie2019/index.html (June 11th, University of British Columbia, Vancouver Canada, co-located with TFP 2019) TFPIE 2019 welcomes submissions describing techniques used in the classroom, tools used in and/or developed for the classroom and any creative use of functional programming (FP) to aid education in or outside Computer Science. Topics of interest include, but are not limited to: FP and beginning CS students FP and Computational Thinking FP and Artificial Intelligence FP in Robotics FP and Music Advanced FP for undergraduates FP in graduate education Engaging students in research using FP FP in Programming Languages FP in the high school curriculum FP as a stepping stone to other CS topics FP and Philosophy The pedagogy of teaching FP FP and e-learning: MOOCs, automated assessment etc. Best Lectures - more details below In addition to papers, we are requesting best lecture presentations. What's your best lecture topic in an FP related course? Do you have a fun way to present FP concepts to novices or perhaps an especially interesting presentation of a difficult topic? In either case, please consider sharing it. Best lecture topics will be selected for presentation based on a short abstract describing the lecture and its interest to TFPIE attendees. The length of the presentation should be comparable to that of a paper. On top of the lecture itself, the presentation can also provide commentary on the lecture. Submissions Potential presenters are invited to submit an extended abstract (4-6 pages) or a draft paper (up to 16 pages) in EPTCS style. The authors of accepted presentations will have their preprints and their slides made available on the workshop's website. Papers and abstracts can be submitted via easychair at the following link: https://easychair.org/conferences/?conf=tfpie2019 After the workshop, presenters will be invited to submit (a revised version of) their article for review. The PC will select the best articles that will be published in the Electronic Proceedings in Theoretical Computer Science (EPTCS). Articles rejected for presentation and extended abstracts will not be formally reviewed by the PC. Dates Submission deadline: May 14th 2019, Anywhere on Earth. Notification: May 20th Workshop: June 11th Submission for formal review: August 18th 2019, Anywhere on Earth Notification of full article: October 6th Camera ready: November 1st Program Committee Alex Gerdes - University of Gothenburg / Chalmers Jurriaan Hage (Chair) - Utrecht University Pieter Koopman - Radboud University, the Netherlands Elena Machkasova - University of Minnesota, Morris, USA Heather Miller - Carnegie Mellon University and EPFL Lausanne Prabhakar Ragde - University of Waterloo, Waterloo, Ontario, Canada Simon Thompson - University of Kent, UK Sharon Tuttle - Humboldt State University, Arcata, USA Note: information on TFP is available at https://www.tfp2019.org/index.html

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[TFP'19] final call for papers (deadline extension): Trends in Functional Programming 2019, 12-14 June 2019, Vancouver, BC, CA
by Peter Achten 08 May '19

08 May '19

-------------------------------- F I N A L C A L L F O R P A P E R S -------------------------------- ====== TFP 2019 ====== 20th Symposium on Trends in Functional Programming 12-14 June, 2019 Vancouver, BC, CA https://www.tfp2019.org/index.html == Important Dates == Sumbission Deadline for Draft Papers Thursday, May 16, 2019 ** extended deadline ** Notification for Draft Papers Tuesday, May 21, 2019 ** extended deadline ** TFPIE Tuesday, June 11, 2019 Symposium Wednesday, June 12, 2019 – Friday, June 14, 2019 Notification of Student Paper Feedback Friday June 21, 2019 Submission Deadline for revised Draft Papers (post-symposium formal review) Thursday, August 1, 2019 Notification for post-symposium submissions Thursday, October 24, 2019 Camera Ready Deadline (both pre- and post-symposium) Friday, November 29, 2019 The symposium on Trends in Functional Programming (TFP) is an international forum for researchers with interests in all aspects of functional programming, taking a broad view of current and future trends in the area. It aspires to be a lively environment for presenting the latest research results, and other contributions (see below at scope). Please be aware that TFP uses two distinct rounds of submissions (see below at submission details). TFP 2019 will be the main event of a pair of functional programming events. TFP 2019 will be accompanied by the International Workshop on Trends in Functional Programming in Education (TFPIE), which will take place on June 11. == Scope == The symposium recognizes that new trends may arise through various routes. As part of the Symposium's focus on trends we therefore identify the following five article categories. High-quality articles are solicited in any of these categories: Research Articles: Leading-edge, previously unpublished research work Position Articles: On what new trends should or should not be Project Articles: Descriptions of recently started new projects Evaluation Articles: What lessons can be drawn from a finished project Overview Articles: Summarizing work with respect to a trendy subject Articles must be original and not simultaneously submitted for publication to any other forum. They may consider any aspect of functional programming: theoretical, implementation-oriented, or experience-oriented. Applications of functional programming techniques to other languages are also within the scope of the symposium. Topics suitable for the symposium include, but are not limited to: Functional programming and multicore/manycore computing Functional programming in the cloud High performance functional computing Extra-functional (behavioural) properties of functional programs Dependently typed functional programming Validation and verification of functional programs Debugging and profiling for functional languages Functional programming in different application areas: security, mobility, telecommunications applications, embedded systems, global computing, grids, etc. Interoperability with imperative programming languages Novel memory management techniques Program analysis and transformation techniques Empirical performance studies Abstract/virtual machines and compilers for functional languages (Embedded) domain specific languages New implementation strategies Any new emerging trend in the functional programming area If you are in doubt on whether your article is within the scope of TFP, please contact the TFP 2019 program chairs, William J. Bowman and Ron Garcia. == Best Paper Awards == To reward excellent contributions, TFP awards a prize for the best paper accepted for the formal proceedings. TFP traditionally pays special attention to research students, acknowledging that students are almost by definition part of new subject trends. A student paper is one for which the authors state that the paper is mainly the work of students, the students are listed as first authors, and a student would present the paper. A prize for the best student paper is awarded each year. In both cases, it is the PC of TFP that awards the prize. In case the best paper happens to be a student paper, that paper will then receive both prizes. == Instructions to Author == Papers must be submitted at: https://easychair.org/conferences/?conf=tfp2019 Authors of papers have the choice of having their contributions formally reviewed either before or after the Symposium. == Pre-symposium formal review == Papers to be formally reviewed before the symposium should be submitted before an early deadline and receive their reviews and notification of acceptance for both presentation and publication before the symposium. A paper that has been rejected in this process may still be accepted for presentation at the symposium, but will not be considered for the post-symposium formal review. == Post-symposium formal review == Papers submitted for post-symposium review (draft papers) will receive minimal reviews and notification of acceptance for presentation at the symposium. Authors of draft papers will be invited to submit revised papers based on the feedback received at the symposium. A post-symposium refereeing process will then select a subset of these articles for formal publication. == Paper categories == There are two types of submission, each of which can be submitted either for pre-symposium or post-symposium review: Extended abstracts. Extended abstracts are 4 to 10 pages in length. Full papers. Full papers are up to 20 pages in length. Each submission also belongs to a category: research position project evaluation overview paper Each submission should clearly indicate to which category it belongs. Additionally, a draft paper submission—of either type (extended abstract or full paper) and any category—can be considered a student paper. A student paper is one for which primary authors are research students and the majority of the work described was carried out by the students. The submission should indicate that it is a student paper. Student papers will receive additional feedback from the PC shortly after the symposium has taken place and before the post-symposium submission deadline. Feedback is only provided for accepted student papers, i.e., papers submitted for presentation and post-symposium formal review that are accepted for presentation. If a student paper is rejected for presentation, then it receives no further feedback and cannot be submitted for post-symposium review. == Format == Papers must be written in English, and written using the LNCS style. For more information about formatting please consult the Springer LNCS web site (http://www.springer.com/lncs) == Program Committee == Program Co-chairs William J. Bowman University of British Columbia Ronald Garcia University of British Columbia Matteo Cimini University of Massachusetts Lowell Ryan Culpepper Czech Technical Institute Joshua Dunfield Queen's University Sam Lindley University of Edinburgh Assia Mahboubi INRIA Nantes Christine Rizkallah University of New South Wales Satnam Singh Google AI Marco T. Morazán Seton Hall University John Hughes Chalmers University and Quviq Nicolas Wu University of Bristol Tom Schrijvers KU Leuven Scott Smith Johns Hopkins University Stephanie Balzer Carnegie Mellon University Viktória Zsók Eötvös Loránd University

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ANN: tensor-safe-0.1.0.1
by Leonardo Piñeyro 08 May '19

08 May '19

Hello everyone, I’m happy to announce a preliminary release of what I called TensorSafe, a library to build structurally correct deep neural networks using dependent types in Haskell. Currently, it also provides the option to compile the models to external frameworks like Keras for Python or Keras JavaScript. I’ve built this as a part of what it is my capstone project to get my degree in computer engineering this year. I’ve learned a ton in a few months, especially thanks to projects like Grenade and the MM Haskell blogs 🙌 I’m still working on details but I think it’s ready for anyone to take a look at it. Any feedback is welcome! • http://hackage.haskell.org/package/tensor-safe • https://github.com/leopiney/tensor-safe Thanks!

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