- Haskell-Cafe - Haskell.org

An org backend to Haddock
by Yuchen Pei 21 Jul '22

21 Jul '22

Hello, I decided to write an Org backend to Haddock[1], so that haskell library documentation can be generated in org mode markup. Compared to the existing backends (html, latex and hoogle), the org format allows utilising features like the infinite levels of heading hierarchy, flexible folding / unfolding, cross-package linking, jumping to any declaration with org-goto and the endless potentials of emacs customisation. It seems to me most information and haskell language features one can find on displayed on hackage are supported by the org backend and included in the output org files, though there are still some rough edges and unsupported language features (like infix declarations and linear types) which I aim to fix. Some example output can be found at [2] (I will need to rename the "assets" part of the url as it is not accurate), including base[4], ghc-prim[5] and ghc-lib-parser[6] (I use it for reference of the GHC API as it is easier to build than GHC). For more information, check out the README file[3]. Given this is not the official version of haddock and my changes are in haddock-api, I'm calling it haddorg-api, for lack of a better name / approach. I'll be happy to contribute my changes upstream if a different license covering my contribution (AGPLv3+) is accepted. Let me know what you think. [1] https://g.ypei.me/haddock.git/tree/haddock-api [2] https://ypei.org/assets/haddorg-output/ [3] https://g.ypei.me/haddock.git/tree/haddock-api/README.org [4] https://ypei.org/assets/haddorg-output/base-4.16.1.0.org.gz [5] https://ypei.org/assets/haddorg-output/ghc-prim-0.8.0.org.gz [6] https://ypei.org/assets/haddorg-output/ghc-lib-parser-9.2.2.20220307.org.gz Best, Yuchen -- PGP Key: 47F9 D050 1E11 8879 9040 4941 2126 7E93 EF86 DFD0 <https://ypei.org/assets/ypei-pubkey.txt>

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Postdoc Vacancy at St Andrews
by Christopher Brown 20 Jul '22

20 Jul '22

The Programming Languages Group at the University of St Andrews seeks a post-doctoral research fellow for a fixed 12-month position. Details of the position can be found here: https://www.vacancies.st-andrews.ac.uk/Vacancies/W/4238/0/352367/889/resear… Vacancy Description School of Computer Science Salary: £34,304 per annum Start date: 1 October 2022 or as soon as possible thereafter Fixed-term: 12 months Applications are sought for a committed Post-doctoral Research Fellow to work with Dr Chris Brown conducting research for a EPSRC funded project entitled Energise: Refactorings and Skeletons for Energy-Aware Applications on High-Performance Embedded Systems. The primary duties will be to implementing refactorings for target languages such as C; proving general soundness of the refactorings using e.g. dependent types; developing new programming abstractions (skeletons) for abstracting common energy-reducing programming patterns; running experiments; writing proofs of correctness. The successful applicant will have (or be near to completion of) a PhD in Programming Languages with expertise in formal semantics of programming languages, compilers, program transformation, lightweight formal methods (including, e.g. dependent types) and/or knowledge of parallelism and non-functional properties, including energy. The post is available on a fixed-term basis for 12 months starting 1st October or as soon as possible thereafter. Further details of the project can be found by contacting Dr Christopher Brown (cmb21(a)st-andrews.ac.uk<mailto:cmb21@st-andrews.ac.uk>). Applications are particularly welcome from women, people from the Black, Asian and Minority Ethnic (BAME) community, and other protected characteristics who are under-represented in research posts at the University. Equality, diversity and inclusion are at the heart of the St Andrews experience. We strive to create a fair and inclusive culture demonstrated through our commitment to diversity awards (Athena Swan, Carer Positive, LGBT Charter, Race Charters and Stonewall). We celebrate diversity by promoting profiles of BAME, LGBTIQ+ staff and supporting networks including the Staff BAME Network; Staff with Disabilities Network; Staff LGBTIQ+ Network; and the Staff Parents & Carers Network. Full details available online: https://www.st-andrews.ac.uk/hr/edi/ Closing Date: 29 July 2022 Interview Date: 23 August 2022 Please quote ref:AR2699GB School of Computer Science Salary: £34,304 per annum Start date: 1 October 2022 or as soon as possible thereafter Fixed-term: 12 months

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Re: [Haskell-cafe] An org backend to Haddock
by Yuchen Pei 19 Jul '22

19 Jul '22

On Tue 2022-07-19 21:58:26 +0800, Ihor Radchenko wrote: > Yuchen Pei <id(a)ypei.org> writes: > >> Given this is not the official version of haddock and my changes are in >> haddock-api, I'm calling it haddorg-api, for lack of a better name / >> approach. I'll be happy to contribute my changes upstream if a >> different license covering my contribution (AGPLv3+) is accepted. >> >> Let me know what you think. > > I am pretty sure that you are asking the Haskell people for upstreaming > ;) Yes - I sent the email to both haskell-cafe and emacs-orgmode, but upstream here means haddock / haddock-api indeed, thanks for clarifying. > > From Org side, it is always welcome when other Free software projects > are making use of Org. > > Also, I looked into > https://g.ypei.me/haddock.git/tree/haddock-api/src/Haddock/Backends/Org/Typ… > > Beware of possible edge cases with "*/~|" in formatting. I am not > sure if text containing such symbols is possible as an input for your > library, but if it is, things may get formatted wrongly. > > For example, text containing "|" anywhere inside a table field must have > "|" escaped using \vert entity. The markup can be escaped using > zero-width space. True. I have not addressed these edge cases in my code, except a quick hack to prepend a space whenever any line a src block / result block has a leading star. Tables on the other hand are extremely rare in Haskell package documentation strings, and having a | in them is even rarer. I do wonder what is the best way to handle cross-package links. Currently I'm using CUSTOM_ID in the format of package-name-x.y.z.Module.Name.IdentifierName, as well as Module.Name.IdentifierName. But this is a "one big org file" approach, and can make navigation slow when say the org file reaches 15+MB in size. Ideally one should be able to navigate the a hackage worth of documentations easily, with working cross-package links and low latency org-goto to jump to any identifier or module, but I don't see how to achieve that. To be further investigated. > > Best, > Ihor Best, Yuchen -- PGP Key: 47F9 D050 1E11 8879 9040 4941 2126 7E93 EF86 DFD0 <https://ypei.org/assets/ypei-pubkey.txt>

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2nd CFP - IFL22 - The 34th Symposium on Implementation and Application of Functional Languages
by Pieter Koopman 15 Jul '22

15 Jul '22

*CALL FOR PAPERS: * The 34th Symposium on Implementation and Application of Functional Languages (IFL 2022) *Submission and registration are open.* See https://ifl22.github.io/. Copenhagen, August 31st-September 2nd, 2022 *Important dates * Draft paper submission: August 7th, 2022 Draft paper notification: August 9th, 2022 Early registration deadline: August 12th, 2022 Late registration deadline: September 2nd, 2022 Symposium: August 31st-September 2nd, 2022 (3 days) *Scope * The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2022 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. Topics of interest to IFL include, but are not limited to: * language concepts * type systems, type checking, type inferencing * compilation techniques * staged compilation * run-time function specialization * run-time code generation * partial evaluation * abstract interpretation * metaprogramming * generic programming * automatic program generation * array processing * concurrent/parallel programming * concurrent/parallel program execution * embedded systems * web applications * embedded domain specific languages * security * novel memory management techniques * run-time profiling performance measurements * debugging and tracing * virtual/abstract machine architectures * validation, verification of functional programs * tools and programming techniques * industrial applications *Submissions and peer-review * Following IFL tradition, IFL 2022 will use a post-symposium review process to produce the formal proceedings. Before the symposium authors submit draft papers. These draft papers will be screened by the program chair to make sure that they are within the scope of IFL. The draft papers will be made available to all participants at the symposium. Each draft paper is presented by one of the authors at the symposium. Notice that it is a requirement that accepted draft papers are presented physically at the symposium. After the symposium, a formal review process will take place, conducted by the program committee. Reviewing is single blind. There will be at least 3 reviews per paper. The reviewers have 6 weeks to write their reviews. For the camera-ready version the authors can make minor revisions which are accepted without further reviewing. Contributions submitted for the draft paper deadline must be between two and twelve pages long. For submission details, please consult the IFL 2022 website at https://ifl22.github.io/. *Where * IFL 2022 will be held physically in Copenhagen, Denmark, arranged by DIKU at the University of Copenhagen. See the IFL 2022 website at https://ifl22.github.io/ for more information. [image: beacon]

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What is the exponential version of dependently-typed Vector and Tensor?
by Johannes Riecken 15 Jul '22

15 Jul '22

I noticed that the definitions of Vector and Tensor have a parallel structure. Vector is an ornamentation of the Peano natural numbers, and Tensor is the parallel construction with multiplication and the multiplicative identity, except that the factors are stored in a list instead of directly multiplying, so that the dependent typing can ensure that the number of elements in the tensor is indeed equal to the product of these factors. (To make it more parallel, the Nat in Vector could be replaced with a list of ones.) ```haskell {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE TypeOperators #-} import GHC.TypeLits import Data.Kind import Numeric.Natural import Data.Proxy data Vector (n :: Nat) a where Nil :: Vector 0 a Cons :: a -> Vector n a -> Vector (n + 1) a data Tensor :: forall n. Vector n Nat -> Type -> Type where Scalar :: a -> Tensor Nil a Dimension :: Vector n (Tensor d a) -> Tensor (Cons n d) a ``` That made me wonder what the exponential version with functions would look like and if that is a useful concept, too, or one that also exists in maths? As going from Vector to Tensor isn't completely mechanical, I had trouble figuring out myself how to go from Tensor to the next higher data structure. Cheers, Johannes

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stack and package candidates
by Henning Thielemann 15 Jul '22

15 Jul '22

In a project my stack.yaml contains this line: - url: https://hackage.haskell.org/package/foobar-0.0/candidate/foobar-0.0.tar.gz This works, but if I update the foobar release candidate then Stack will not notice and stick to the old version. How can I invalidate or remove the cached foobar version?

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Folding nested foldables -- Known pattern?
by Ivan Perez 12 Jul '22

12 Jul '22

Spam detection software, running on the system "mail.haskell.org", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Hi cafÃ© TL;DR: In Copilot, we have an ad-hoc notion of a nestable data structure that can be folded into a list. I'm trying to rely on standard classes as much as possible. Is there a known class to capture the idea of folding nested data structures (e.g., transitive foldable?) [...] Content analysis details: (5.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (ivanperezdominguez[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.0 BAYES_40 BODY: Bayes spam probability is 20 to 40% [score: 0.2680] 5.0 UNWANTED_LANGUAGE_BODY BODY: Message written in an undesired language 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid The original message was not completely plain text, and may be unsafe to open with some email clients; in particular, it may contain a virus, or confirm that your address can receive spam. If you wish to view it, it may be safer to save it to a file and open it with an editor.

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mastered Haskell and need a new challenge???
by Anand, Christopher 11 Jul '22

11 Jul '22

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Call for Reviewers APLAS 2022 Artifact Evaluation Committee
by Arpita Dutta 01 Jul '22

01 Jul '22

Dear all, The /20th Asian Symposium on Programming Languages and Systems/ (APLAS'22) is going to be holding its first /Artifact Evaluation Committee/ (AEC). The artifact evaluation process aims to promote, share, and catalogue the research artifacts of papers accepted to the APLAS research track. We are looking for motivated researchers at all academic stages (Ph.D. Students, Researchers, Lecturers, & Professors) to join us on the inaugural APLAS'22 AEC. The self-nomination form is available at: https://forms.gle/rJREG9DiFQHegZmD9 To nominate other people please use the following form: https://forms.gle/KFiQYLjELMsEjGLp8 As a committee member, your primary responsibility will be to review artifacts submitted by authors of accepted papers and ensure that the artifact is a faithful representation of the accepted paper's results. This will involve interacting with some tooling provided by the authors, check if the results of the main paper are consistent with the claims in the paper, and are also reproducible for researchers to come. APLAS will use a three-phase artifact review process: Kick-The-Tyres; Review the Artifact; and Iron-out-the-Wrinkles. Reviewing guidance for committee members will be made available once the committee has been formed. We will close nominations on: Friday 08 July 2022 (AOE) and notify the selected committee members on: Friday 15 July 2022 (AOE) We expect most of the reviewing process to be performed between 22nd August 2022 and 19th September 2022. We expect each artifact to take around eight hours to review and we will look to assign each reviewer three to four reviews. For each artifact, we will assign a Lead Reviewer to lead the reviewing process. Salient information about the reviewing process can be found online: https://2022.splashcon.org/track/aplas-2022-aec#Reviewer-Information<https://2022.splashcon.org/track/aplas-2022-aec#Reviewer-Information> Come join us to improve the quality of research in our field! Thanks Arpita Dutta and Jan de Muijnck-Hughes APLAS'22 AEC Co-Chairs. This call was adapted from the PLDI'22 AEC Call for Nominations.

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Where does η-equivalence stop?
by Hécate 29 Jun '22

29 Jun '22

Hi Café! I was wondering if anyone knew of a centralised list of occurrences where GHC Haskell stops upholding η-equivalence. I am interested in both type changes and operational semantics. So far I've collected the following things: * Rank-2 types * Monomorphism restriction * The presence of seq * Non-pedantic bottoms One source is the GHC Manual¹, and Neil Mitchell pointed me to the list of bugs and limitations of HLint². If you have other examples, or explanations of the mechanisms at play here, I would be very interested, and intend to upstream those in the GHC manual. Cheers, Hécate [¹] https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/bugs.html#e… [²] https://github.com/ndmitchell/hlint#bugs-and-limitations -- Hécate ✨ 🐦: @TechnoEmpress IRC: Hecate WWW: https://glitchbra.in RUN: BSD

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