- Haskell-Cafe - Haskell.org

PLMW at ICFP: Call for Scholarship Applications (due 17 May)
by Sam Tobin-Hochstadt 07 May '19

07 May '19

ACM SIGPLAN Programming Languages Mentoring Workshop Co-located with ICFP'19 PLMW web page: https://icfp19.sigplan.org/home/PLMW-ICFP-2019 The purpose of the programming languages mentoring workshop (PLMW) is to encourage senior undergraduate and early career (first or second year) to pursue careers in programming language research. We are specifically interested in attracting groups who have traditionally not had the opportunity to participate in research in functional programming. This workshop will be a combination of learning about the work being done in several areas of programming language research and mentoring with respect to helping students prepare for graduate school and the rest of their career. We will bring together leaders in programming language research from academia and industry to give talks on the kind of research typically performed after obtaining a Ph.D. The workshop will engage students, specifically interested in programming language research, in a process of imagining how they might contribute to the world. We especially encourage women and underrepresented minority students to attend PLMW. This workshop is part of the activities surrounding ICFP, the International Conference on Functional Programming, and takes place the day before the main conference. One goal of the workshop is to make ICFP conference more accessible to newcomers. We hope that participants will stay through the entire conference. ## Travel Scholarship Applications (Due 17 May) Please fill out this form by 17 May to apply for travel funding. https://forms.gle/QEvBateG7PRywB336 See the PLMW web page for additional details. The workshop registration is open to all. Students with alternative sources of funding are welcome.

1 0

Haskell Platform / GHC 8.6.5
by Philipp Hausmann 07 May '19

07 May '19

Hi All I noticed that the Windows Download Link on https://www.haskell.org/platform/windows.html points to the 8.6.3 version. When can we expect an updated Haskell Platform release to be available? To give some background, we had some trouble where students got Access Violation crashes on Windows machines using GHC 8.6.3 which is fixed on GHC 8.6.5. In the end we updated to GHC 8.6.5 using the Binary GHC release, but this is quite ugly as it requires fiddling with the PATH... Best, Philipp

1 0

Final CFP: Haskell Symposium due this Friday
by Richard Eisenberg 07 May '19

07 May '19

================================================================================ ACM SIGPLAN CALL FOR SUBMISSIONS Haskell Symposium 2019 Berlin, Germany 22--23 August, 2019 http://www.haskell.org/haskell-symposium/2019/ ================================================================================ The ACM SIGPLAN Haskell Symposium 2019 will be co-located with the 2019 International Conference on Functional Programming (ICFP). **NEW THIS YEAR**: We will be using a lightweight double-blind reviewing process. See further information below. The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. Topics of interest include: * Language design, with a focus on possible extensions and modifications of Haskell as well as critical discussions of the status quo; * Theory, such as formal semantics of the present language or future extensions, type systems, effects, metatheory, and foundations for program analysis and transformation; * Implementations, including program analysis and transformation, static and dynamic compilation for sequential, parallel, and distributed architectures, memory management, as well as foreign function and component interfaces; * Libraries, that demonstrate new ideas or techniques for functional programming in Haskell; * Tools, such as profilers, tracers, debuggers, preprocessors, and testing tools; * Applications, to scientific and symbolic computing, databases, multimedia, telecommunication, the web, and so forth; * Functional Pearls, being elegant and instructive programming examples; * Experience Reports, to document general practice and experience in education, industry, or other contexts; * System Demonstrations, based on running software rather than novel research results. Regular papers should explain their research contributions in both general and technical terms, identifying what has been accomplished, explaining why it is significant, and relating it to previous work, and to other languages where appropriate. Experience reports and functional pearls need not necessarily report original academic research results. For example, they may instead report reusable programming idioms, elegant ways to approach a problem, or practical experience that will be useful to other users, implementers, or researchers. The key criterion for such a paper is that it makes a contribution from which other Haskellers can benefit. It is not enough simply to describe a standard solution to a standard programming problem, or report on experience where you used Haskell in the standard way and achieved the result you were expecting. System demonstrations should summarize the system capabilities that would be demonstrated. The proposals will be judged on whether the ensuing session is likely to be important and interesting to the Haskell community at large, whether on grounds academic or industrial, theoretical or practical, technical, social or artistic. Please contact the program chair with any questions about the relevance of a proposal. Submission Details ================== Early and Regular Track ----------------------- The Haskell Symposium uses a two-track submission process so that some papers can gain early feedback. Strong papers submitted to the early track are accepted outright, and the others will be given their reviews and invited to resubmit to the regular track. Papers accepted via the early and regular tracks are considered of equal value and will not be distinguished in the proceedings. Although all papers may be submitted to the early track, authors of functional pearls and experience reports are particularly encouraged to use this mechanism. The success of these papers depends heavily on the way they are presented, and submitting early will give the program committee a chance to provide feedback and help draw out the key ideas. Formatting ---------- Submitted papers should be in portable document format (PDF), formatted using the ACM SIGPLAN style guidelines. Authors should use the `acmart` format, with the `sigplan` sub-format for ACM proceedings. For details, see: http://www.sigplan.org/Resources/Author/#acmart-format It is recommended to use the `review` option when submitting a paper; this option enables line numbers for easy reference in reviews. Functional pearls, experience reports, and demo proposals should be labelled clearly as such. Lightweight Double-blind Reviewing ---------------------------------- Haskell Symposium 2019 will use a lightweight double-blind reviewing process. To facilitate this, submitted papers must adhere to two rules: 1. Author names and institutions must be omitted, and 2. References to authors’ own related work should be in the third person (e.g., not “We build on our previous work …” but rather “We build on the work of …”). The purpose of this process is to help the reviewers come to an initial judgment about the paper without bias, not to make it impossible for them to discover the authors if they were to try. Nothing should be done in the name of anonymity that weakens the submission or makes the job of reviewing the paper more difficult (e.g., important background references should not be omitted or anonymized). In addition, authors should feel free to disseminate their ideas or draft versions of their paper as they normally would. For instance, authors may post drafts of their papers on the web or give talks on their research ideas. A reviewer will learn the identity of the author(s) of a paper after a review is submitted. Page Limits ----------- The length of submissions should not exceed the following limits: Regular paper: 12 pages Functional pearl: 12 pages Experience report: 6 pages Demo proposal: 2 pages There is no requirement that all pages are used. For example, a functional pearl may be much shorter than 12 pages. In all cases, the list of references is not counted against these page limits. Deadlines --------- Early track: Submission deadline: 15 March 2019 (Fri) Notification: 19 April 2019 (Fri) Regular track and demos: Submission deadline: 10 May 2019 (Fri) Notification: 21 June 2019 (Fri) Camera-ready deadline for accepted papers: 30 June 2019 (Sun) Deadlines are valid anywhere on Earth. Submission ---------- Submissions must adhere to SIGPLAN's republication policy (http://sigplan.org/Resources/Policies/Republication/) and authors should be aware of ACM's policies on plagiarism (https://www.acm.org/publications/policies/plagiarism) The paper submission deadline and length limitations are firm. There will be no extensions, and papers violating the length limitations will be summarily rejected. Papers should be submitted through HotCRP at: https://haskell19.hotcrp.com/ Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. Supplementary material: Authors have the option to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at it. This supplementary material should not be submitted as part of the main document; instead, it should be uploaded as a separate PDF document or tarball. Supplementary material should be uploaded at submission time, not by providing a URL in the paper that points to an external repository. Authors are free to upload both anonymized and non-anonymized supplementary material. Anonymized supplementary material will be visible to reviewers immediately; non-anonymized supplementary material will be revealed to reviewers only after they have submitted their review of the paper and learned the identity of the author(s). Resubmitted Papers: Authors who submit a revised version of a paper that has previously been rejected by another conference have the option to attach an annotated copy of the reviews of their previous submission(s), explaining how they have addressed these previous reviews in the present submission. If a reviewer identifies him/herself as a reviewer of this previous submission and wishes to see how his/her comments have been addressed, the principal editor will communicate to this reviewer the annotated copy of his/her previous review. Otherwise, no reviewer will read the annotated copies of the previous reviews. Travel Support ============== Student attendees with accepted papers can apply for a SIGPLAN PAC grant to help cover travel expenses. PAC also offers other support, such as for child-care expenses during the meeting or for travel costs for companions of SIGPLAN members with physical disabilities, as well as for travel from locations outside of North America and Europe. For details on the PAC program, see its web page (http://pac.sigplan.org) Proceedings =========== Accepted papers will be included in the ACM Digital Library. Authors must grant ACM publication rights upon acceptance (http://authors.acm.org/main.html) Authors are encouraged to publish auxiliary material with their paper (source code, test data, etc.); they retain copyright of auxiliary material. Accepted proposals for system demonstrations will be posted on the symposium website but not formally published in the proceedings. All accepted papers and proposals will be posted on the conference website one week before the meeting. Publication date: The official publication date of accepted papers is the date the proceedings are made available in the ACM Digital Library. This date may be up to two weeks prior to the first day of the conference. The official publication date affects the deadline for any patent filings related to published work. Program Committee ================= Ki-Yung Ahn Hannam University Christiaan Baaij QBayLogic B.V. José Manuel Calderón Trilla Galois, Inc Benjamin Delaware Purdue University Richard Eisenberg (chair) Bryn Mawr College Jennifer Hackett University of Nottingham Kazutaka Matsuda Tohoku University Trevor McDonell Utrecht University Ivan Perez NIA / NASA Formal Methods Nadia Polikarpova University of California, San Diego Norman Ramsey Tufts University Christine Rizkallah University of New South Wales Eric Seidel Bloomberg LP Alejandro Serrano Mena Utrecht University John Wiegley Dfinity Foundation Thomas Winant Well-Typed LLP Ningning Xie University of Hong Kong If you have questions, please contact the chair at: rae(a)richarde.dev ================================================================================

1 0

ARM builds of GHC
by Vanessa McHale 06 May '19

06 May '19

Hi all, Are there any plans to release/distribute ARM builds of GHC for the 8.8.* series? The most recent GHC to have ARM binaries distributed seems to be 8.4.2, which regrettably has a bug that makes it unsuitable for my purposes. Cheers, Vanessa McHale

1 0

[ANNOUNCEMENT] 11th International School on Rewriting (ISR'19), 1-6 July 2019, MINES ParisTech, France
by Johannes Waldmann 06 May '19

06 May '19

Dear Cafe - if your're using Haskell, you are using (term) rewriting: both first order (pattern matching on algebraic data types) and higher order (lambda calculus). Here is your chance to get the fundamentals right, and see more applications: the 11th International School on Rewriting (ISR'19), 1-6 July 2019, MINES ParisTech, France. https://isr2019.mines-paristech.fr/ Deadline for early registration: May 17 full text of call for participation http://lists.tcs.ifi.lmu.de/pipermail/loginf/2019/001723.html - J.W.

1 0

Call for Participation: Compose Conference [NYC, Jun 22- 23 2019]
by Gershom B 03 May '19

03 May '19

=============================================== Call for Participation Compose Conference 2019 Mon June 24 - Tue June 25 2019 (Unconference on Sat Jun 22 - Sun Jun 23) New York, NY http://www.composeconference.org/2019 =============================================== The practice and craft of functional programming :: Conference Compose is a conference for typed functional programmers, focused specifically on Haskell, OCaml, F#, SML, and related technologies. Typed functional programming has been taken up widely, by industry and hobbyists alike. For many of us it has renewed our belief that code should be beautiful, and that programming can be as enjoyable as it is practical. Compose is about bringing together functional programmers of all levels of skill and experience — from technical leads to novices, and from long-time hackers to students just getting started. It will feature a two days of great and wide-ranging talks * Invited Keynotes Donya Quick - Making Algorithmic Music David Spivak - Compositional Graphical Logic * Accepted Talks and Tutorials Kenny Foner - Functors of the World, Unite! Phillip Carter - The anatomy of the F# tools for Visual Studio Sebastien Mondet - Genspio: Generating Shell Phrases In OCaml Justin Le - Applicative Regular Expressions using the Free Alternative Gaetano Checinski - Buckaroo SAT - Solving a partially revealed SAT problem for Package Management Richard Feldman - From Rails to Elm and Haskell Samuel Gélineau - Stuck macros: deterministically interleaving macro-expansion and typechecking Vaibhav Sagar - Yes, IHaskell Can Do That! Fintan Halpenny - Bowl Full of Lentils Aditya Siram - A Tase Of ATS Ward Wheeler, Alex Washburn, Callan McGill - Phylogenetic Software in Haskell Igor Trindade Oliveira - Type Driven Secure Enclave Development using Idris David Christiansen - Bidirectional Type Checking Chris Smith - Teaching the intersection of mathematics and functional programming Brandon Kase - Fast Accumulation on Streams James Koppel - The Best Refactoring You’ve Never Heard Of Allister Beharry - Using Dependent Types in an F# DSL for Linear Algebra Diego Balseiro - Bridge Haskell and ReasonML in Production * Full abstracts: http://www.composeconference.org/2019/program * Conference Registration: https://www.eventbrite.com/e/new-york-compose-2019-tickets-56751182314 * Unconference Registration: https://www.eventbrite.com/e/new-york-compose-unconference-2019-tickets-603… * Follow @composeconf on twitter for news: https://twitter.com/composeconf * On freenode irc, chat with fellow attendees at #composeconference * Corporate sponsorships are welcome. Current sponsors list forthcoming. * Policies (diversity and anti-harassment): http://www.composeconference.org/conduct * Email us with any questions at info(a)composeconference.org * Please forward this announcement to interested parties and lists.

1 0

Static linking against X11
by Vanessa McHale 01 May '19

01 May '19

Hi all, I'm trying to cross-compile xmobar for aarch64-linux-gnu. The cross compiler that comes with my version of Ubuntu works with a later GLIBC than the host platform, so I figured I'd make a static executable instead - this approach had worked with e.g. cabal-install. Unfortunately, I get the following: Resolving dependencies... Build profile: -w ghc-8.6.4 -O1 In order, the following will be built (use -v for more details): - xmobar-vanessa-0.1.0.0 (exe:xmobar) (first run) Preprocessing executable 'xmobar' for xmobar-vanessa-0.1.0.0.. Building executable 'xmobar' for xmobar-vanessa-0.1.0.0.. Linking /home/vanessa/programming/haskell/done/xmobar-vanessa/dist-newstyle/build/aarch64-linux/ghc-8.6.4/xmobar-vanessa-0.1.0.0/x/xmobar/build/xmobar/xmobar ... /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/local/lib/aarch64-linux-gnu-ghc-8.6.4/rts/libHSrts.a(Linker.o): in function `internal_dlopen': /home/vanessa/cross/ghc-8.6.4/rts/Linker.c:600:0: error: warning: Using 'dlopen' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /home/vanessa/.cabal/store/ghc-8.6.4/network-3.1.0.0-b60cf17d11d7eda024959ae28f710f94d7565bcd8e3372f04f32d2600769c2c1/lib/libHSnetwork-3.1.0.0-b60cf17d11d7eda024959ae28f710f94d7565bcd8e3372f04f32d2600769c2c1.a(HsNet.o): in function `hsnet_getaddrinfo': HsNet.c:(.text+0x10): warning: Using 'getaddrinfo' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_io.o): in function `require_socket': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:68:0: error: undefined reference to `xcb_take_socket' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_io.o): in function `poll_for_event': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:245:0: error: undefined reference to `xcb_poll_for_event' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:243: undefined reference to `xcb_poll_for_queued_event' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_io.o): in function `poll_for_response': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:284:0: error: undefined reference to `xcb_poll_for_reply64' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_io.o): in function `_XSend': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:499:0: error: undefined reference to `xcb_writev' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_io.o): in function `_XEventsQueued': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:364:0: error: undefined reference to `xcb_connection_has_error' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_io.o): in function `_XReadEvents': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:441:0: error: undefined reference to `xcb_connection_has_error' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:400: undefined reference to `xcb_wait_for_event' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_io.o): in function `_XAllocIDs': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:549:0: error: undefined reference to `xcb_generate_id' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_io.o): in function `_XReply': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_io.c:609:0: error: undefined reference to `xcb_wait_for_reply64' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(ClDisplay.o): in function `XCloseDisplay': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/ClDisplay.c:71:0: error: undefined reference to `xcb_disconnect' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(OpenDis.o): in function `OutOfMemory': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/OpenDis.c:705:0: error: undefined reference to `xcb_disconnect' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(OpenDis.o): in function `XOpenDisplay': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/OpenDis.c:255:0: error: undefined reference to `xcb_get_setup' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/OpenDis.c:498: undefined reference to `xcb_get_maximum_request_length' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/lib/../lib/libX11.a(xcb_disp.o): in function `_XConnectXCB': /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_disp.c:69:0: error: undefined reference to `xcb_parse_display' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_disp.c:76: undefined reference to `xcb_connect_to_display_with_auth_info' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_disp.c:81: undefined reference to `xcb_get_file_descriptor' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_disp.c:84: undefined reference to `xcb_generate_id' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_disp.c:92: undefined reference to `xcb_connection_has_error' /usr/lib/gcc-cross/aarch64-linux-gnu/8/../../../../aarch64-linux-gnu/bin/ld: /tmp/cpkg-2c6d48cdbb4678ca/libX11-1.6.7/src/xcb_disp.c:78: undefined reference to `xcb_connect' collect2: error: ld returned 1 exit status `aarch64-linux-gnu-gcc' failed in phase `Linker'. (Exit code: 1) I looked in libX11.a with nm /usr/aarch64-linux-gnu/lib/libX11.a | rg 'xcb_take_socket' which yields U xcb_take_socket which, as I understand, means that something is screwed up in the X11 static linking (but I know less about systems programming and linkers than Haskell). Does anyone know how to fix such a problem? Cheers, Vanessa McHale

2 1

Trying to find a Haskell unikernel project which is not HaLVM.
by Magicloud Magiclouds 01 May '19

01 May '19

Hi, About half an year ago, while I was digging a sanity check issue in 8.6.1, I accidently got a Trac mentioning a Haskell unikernel project. The name is H prefixed (apparently), and a bit of long. Now I am trying to dig more on that project, but could not find it anywhere. Does anyone have a clue? Thanks. -- 竹密岂妨流水过山高哪阻野云飞 And for G+, please use magiclouds#gmail.com.

3 5

Repa array and Data.Vector.Storable.Mutable.
by PICCA Frederic-Emmanuel 01 May '19

01 May '19

Hello I would like a function which allows to freeze a Mutable Vector into a Repa array. of type Array F DIM2 a It seems to me that the the foreignPtr ownership should be transfer to the Repa Array, but I can not find a way to do this... So what is the proper way to achieve this ? thansk for your help. Frederic

2 1

Agda's BUILTIN Naturals in Haskell
by Georgi Lyubenov 30 Apr '19

30 Apr '19

Hey, Is there any way to do something similar to what Agda does with natural numbers via BUILTIN pragmas? More precisely I want to have correct-by-construction natural numbers, that at runtime are treated as `Integer`s. My initial idea was to abuse rewrite rules to turn `data N = Z | S N` into `Integer` terms somehow, but I'm not sure if this is possible. ======= Georgi

4 3