From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83]) by c5ff346549e7 (Postfix) with ESMTPS id 387525D4 for ; Tue, 10 Mar 2020 14:29:16 +0000 (UTC) X-IronPort-AV: E=Sophos;i="5.70,537,1574118000"; d="scan'208,217";a="439679507" Received: from sympa.inria.fr ([193.51.193.213]) by mail2-relais-roc.national.inria.fr with ESMTP; 10 Mar 2020 15:29:14 +0100 Received: by sympa.inria.fr (Postfix, from userid 20132) id 30D377F456; Tue, 10 Mar 2020 15:29:14 +0100 (CET) Received: from mail3-relais-sop.national.inria.fr (mail3-relais-sop.national.inria.fr [192.134.164.104]) by sympa.inria.fr (Postfix) with ESMTPS id 0D36E7EEA4 for ; Tue, 10 Mar 2020 15:29:10 +0100 (CET) X-IronPort-AV: E=Sophos;i="5.70,537,1574118000"; d="scan'208,217";a="341895173" Received: from set.irisa.fr (HELO set) ([131.254.10.170]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 10 Mar 2020 15:28:56 +0100 From: Alan Schmitt To: "lwn" , "cwn" , caml-list@inria.fr, comp@lists.orbitalfox.eu Date: Tue, 10 Mar 2020 15:28:56 +0100 Message-ID: <87eeu0i8rb.fsf@polytechnique.org> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="=-=-=" Subject: [Caml-list] Attn: Development Editor, Latest OCaml Weekly News Reply-To: Alan Schmitt X-Loop: caml-list@inria.fr X-Sequence: 18048 Errors-to: caml-list-owner@inria.fr Precedence: list Precedence: bulk Sender: caml-list-request@inria.fr X-no-archive: yes List-Id: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: --=-=-= Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hello Here is the latest OCaml Weekly News, for the week of March 03 to 10, 2020. Table of Contents =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80 Non opam workflows First release of metapp OCaml 4.10 released Transept 0.1.0: Generalised Parser Combinators Multicore OCaml: Feb 2020 update owl 0.8.0 and 0.9.0 released Parser combinators vs. parser preprocessors? Dune 2.4.0 Tyxml 4.4.0 first release of oplsr: an OCaml wrapper to the pls R package - Partial Lea= st Squares (PLS) regression Old CWN Non opam workflows =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90 Archive: Manas asked =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80 Very recently, I learnt that there is a significant chunk of users in the OCaml community that does not use opam to install packages. As a small initiative to contribute to tooling, I want to ensure what I build is compatible with these workflows - workflows I'm not familiar with myself. I'd love to learn more - what does it look like? How do you setup your compiler, dune and merlin (and/or soon ocamllsp)? How do you configure your editor to find them and what would make it easier to do so? I'm told of Duniverse as one tool that being used in these non-opam workflows. Are there any more popular ones out there? Th=C3=A9o Zimmermann replied =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 I am one of these people. I mostly rely on Nix, whose package repository nixpkgs provides package sets for all (relatively recent) versions of OCaml. These package sets are not generally as complete as what you can find on opam, so it sometimes happens that I open a PR on the nixpkgs repository to add a new package (and in the meantime I use my local updated copy of the nixpkgs repo). You can see the list of available OCaml packages at: (This is for the default OCaml version, currently 4.07 in nixpkgs-unstable. Other package sets are called `ocaml-ng.ocamlPackages_4_0X' but are not shown in this web search.) Most OCaml packages are available at a single version in nixpkgs (even though you can choose your version of OCaml). To gain more flexibility on the exact version I use in one of my project, I am planning to test Duniverse. At that point, I would rely on Duniverse for library dependencies, but I would still rely on Nix to install OCaml, findlib, Dune, Duniverse (I'll have to take care of packaging it), utop, merlin, or ocamlformat. Nix is pretty straightforward to use. You generally provide a `default.nix' at the root of your repository, and it will list the dependencies that you use. When you want to go develop your project, you just enter a special shell (with the `nix-shell' command) and you are in an environment where the tools you need are in `PATH' and the libraries you need are in `OCAMLPATH'. There's just one tool that I needed special configuration for: `ocamlformat' (especially because some projects use it and some do not). When I use it, my `default.nix' contains: =E2=94=8C=E2=94=80=E2=94=80=E2=94=80=E2=94=80 =E2=94=82 shellHook =3D '' =E2=94=82 export OCAMLFORMAT_LOCATION=3D${ocamlformat} =E2=94=82 ''; =E2=94=94=E2=94=80=E2=94=80=E2=94=80=E2=94=80 which will export an environment variable when I enter the shell. And my `.emacs' contains: =E2=94=8C=E2=94=80=E2=94=80=E2=94=80=E2=94=80 =E2=94=82 (setq ocamlformat-location (getenv "OCAMLFORMAT_LOCATION")) =E2=94=82 (when (> (length ocamlformat-location) 0) =E2=94=82 (add-to-list 'load-path (concat ocamlformat-location "/share/e= macs/site-lisp")) =E2=94=82 (require 'ocamlformat) =E2=94=82 (add-hook 'tuareg-mode-hook =E2=94=82 (lambda () (add-hook 'before-save-hook 'ocamlformat-before-= save)))) =E2=94=94=E2=94=80=E2=94=80=E2=94=80=E2=94=80 I want to ensure what I build is compatible with these workflows If you mean as a library author, then all you have to ensure is that you use Dune as the build system (makes the Duniverse workflow better, and makes it easier to package your library in nixpkgs, cf. `buildDunePackage' documented at ). Rwmjones also replied =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 You might want to check out the Fedora OCaml packages. Unfortunately I don't have a convenient way to link to the whole list, but if you look at all the OCaml packages here: * and then if you substitute the `ocaml-' in two places in this URL: (example showing `ocaml-re' package), you can see how we build and package them in the `%prep', `%build' and `%install' sections. And yes, please make sure your software doesn't depend on opam. Building everything in your home directory is not suitable for enterprise software distribution. First release of metapp =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90 Archive: Thierry Martinez announced =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80= =E2=94=80 I am happy to announce the first release of `metapp', yet another preprocessor for OCaml. Similarly to [`ppx_optcomp'], `metapp' is a PPX rewriter. But instead of introducing a specific DSL for preprocessor directives, `metapp' provides a `[%meta ...]' extension, where the dots `...' are arbitrary OCaml expressions that are substituted at compile-time by the AST nodes they evaluate into. These expressions build AST nodes either by (anti-)quoting some code directly, or by using `compiler-libs' ([`Parsetree'], [`Ast_helper'], =E2=80=A6). In particular, this preprocessor is easy to use for conditional compilation, and is an alternative to [`cppo'] and [`ppx_optcomp']. =E2=94=8C=E2=94=80=E2=94=80=E2=94=80=E2=94=80 =E2=94=82 let option_get o =3D =E2=94=82 [%meta if Sys.ocaml_version >=3D "4.08.0" then =E2=94=82 [%e Option.get o] =E2=94=82 else =E2=94=82 [%e match o with =E2=94=82 | None -> invalid_arg "option_get" =E2=94=82 | Some x -> x]] =E2=94=94=E2=94=80=E2=94=80=E2=94=80=E2=94=80 In this example, the code between `[%e ... ]' is "anti-quoted": it is the code that is inserted (conditionally) in the rewritten module. Of course, the anti-quoted code can contain itself some `[%meta ...]' code. `[%meta ...]' can even itself contain other levels of `[%meta ...]' code for multi-stage programming. An example of usage of `metapp' is the [`metaquot'] package, which implements the same quoters as `ppx_tools.metaquot': `[%expr ...]', `[%type: ...]', etc. These quoters are implemented by meta-programming: the meta-code introspects `Parsetree.cmi' from `compiler-libs' to generate the code matching the current OCaml version. [`ppx_optcomp'] [`Parsetree'] [`Ast_helper'] [`cppo'] [`metaquot'] Rapha=C3=ABl Proust added =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80 To potentially save a few second to the next readers: seems to be the repo where it is hosted. Thierry Martinez then said =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80= =E2=94=80 Thanks, @raphael-proust! The package is also available via opam: `opam install metapp' (and `metaquot' is available via opam as well). OCaml 4.10 released =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90 Archive: octachron continued this thread =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80= =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 The Merlin team has just released a preview version of Merlin which is compatible with 4.10.0 (Merlin is an editor service that provides modern IDE features for OCaml) . This is a preview version: =E2=80=A2 the support for short-path is disabled =E2=80=A2 only OCaml 4.10.0 is supported in this preview It can be installed via opam with the usual =E2=94=8C=E2=94=80=E2=94=80=E2=94=80=E2=94=80 =E2=94=82 opam install merlin =E2=94=94=E2=94=80=E2=94=80=E2=94=80=E2=94=80 Transept 0.1.0: Generalised Parser Combinators =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90= =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90 Archive: Didier Plaindoux announced =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80= =E2=94=80 I=E2=80=99m happy to announce the first release of Transept an OCaml implementation of generalized parsers combinators. This implementation has been inspired by a 19 years old paper - written by Daan Leijen and Erik Meijer - titled =E2=80=9CParsec: Direct S= tyle Monadic Parser Combinators For The Real World=E2=80=9D [1]. The current implementation provides basic combinators dedicated to char, chars recognition but also conjunction, sequence, repetition and more. Since the current design relies on the abstract definition of manipulated element most of the parsers are generic and can be used with streams of chars or something else. Finally, with this library, I wanted to share my love of OCaml modules =F0=9F=A4=97 Opam: [1] Didier Wenzek then said =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 It good to see yet another parser combinator for OCaml, even if this makes more difficult the choice of one of them. I believe this highlights how well OCaml shines for this kind of applications where both high-level expressiveness and performance matter. [`angstrom'] is one the alternatives and provides a comparison with others. It would be good to position `transept' here. There is also a more recent article with a radically new approach: [A Typed, Algebraic Approach to Parsing] by Neelakantan R. Krishnaswami and Jeremy Yallop - PLDI 2019. This paper proposes a [library of parser combinators] for context-free expressions, an algebraic presentation of the context-free languages. The key points are =E2=80=A2 the use of types to statically reject any language which cannot= be parsed unambiguously and linearly; =E2=80=A2 the use of staging, with OcamlBER, to produce parsers which performance are close to those of hand-written code. [`angstrom'] [A Typed, Algebraic Approach to Parsing] [library of parser combinators] Multicore OCaml: Feb 2020 update =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90= =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90 Archive: Continuing this thread, Rwmjones asked =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80= =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 Hi Anil (or anyone!). Is there a place I can find more about breaking changes that might be made to C extensions? As you may know we have a lot of C code which interfaces with OCaml, both as ordinary extensions written in C, but also embedding OCaml in C programs (although that's much more rare), and I'd like a heads up about what's likely to change. Anil Madhavapeddy replied =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 Hi @rwmjones! In a nutshell: no breaking C changes. The longer version is that we implemented two different minor collectors in order to evaluate various tradeoffs systematically: =E2=80=A2 a concurrent minor collector that requires a read barrier and s= ome C API changes in order to create more safe points =E2=80=A2 a stop-the-world minor collector that doesn't require a read ba= rrier and no extra C API changes, but would probably cause longer pauses The good news is that our STW collector scales up much better than we expected (tested to 24 cores), and so our first domains patchset will almost certainly use that version now. We expect to shift to a concurrent (and possibly pauseless) collection algorithm at some future point, but in terms of upstreaming it looks like we should be able to delay any C API changes until after the first version of multicore has landed. Do you have any nice standalone candidate programs using the C FFI we could add to Sandmark? owl 0.8.0 and 0.9.0 released =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90= =E2=95=90=E2=95=90=E2=95=90 Archive: Marcello Seri announced =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 We are happy to announce *two* new releases of `owl': a dedicated system for scientific and engineering computing in OCaml. Since our previous announcement in July last year, there has been an [enormous amount of work] going on to cleanup and extend owl's internals and its interfaces. In this period we have been trying to release often and keep disruption to a minimum. Owl 0.8.0 and 0.9.0 are exceptional in this respect: =E2=80=A2 `owl.0.8.0': =E2=80=A2 the discrepancy between `owl-base' (pure ocaml) and `owl' (li= nks cblas/lapacke) interfaces started becoming a problem in few places. In this release many interfaces have been unified and reused. The algodiff module has undergone a similar refactoring. Although most users should be shielded from these changes, they may break existing code, requiring an upper bound on owl and some localized updates. This should mostly boil down to changes like =E2=94=8C=E2=94=80=E2=94=80=E2=94=80=E2=94=80 =E2=94=82 -module CGraph_D =3D Owl_computation_engine.Make_Graph (Owl= _computation_cpu_device.Make (Dense.Ndarray.D)) =E2=94=82 +module CGraph_D =3D Owl_computation_engine.Make_Graph (Owl= _computation_cpu_device.Make (Owl_algodiff_primal_ops.D)) =E2=94=94=E2=94=80=E2=94=80=E2=94=80=E2=94=80 =E2=80=A2 this is the last edition supporting OCaml compiler versions < 4.10.0 (more on this later). =E2=80=A2 `owl.0.9.0': the main difference between `0.8.0' and `0.9.0' is= that owl now requires OCaml 4.10.0. This release of OCaml introduces *extended indexing operators*. With them we can now write things like `x.%{0;3}' (for indexing) and `x.${[0:2];[2;4]}' (for slicing) instead of the more cumbersome `x.%{[|0;3|]}' and `x.${[[0:2];[2;4]]}'. The project is thoroughly documented at [ocaml.xyz ] where you can find multiple examples of use. A lot of work has (and is) been going into improving the documentation, you can find the results in the new [owl book]: . This is currently targeting the development version of owl, so using `master' or `0.9.0' is the best bet if you want to try the examples out. One of the issue of the old documentation was that it was getting stale very fast: the book is reusing some of the infrastructure of RWO, so all examples get recompiled and retested continuously to ensure their correctness. As a final note, we would like to send a huge thank to the [OCaml Software Foundation], see also the [announcement made on this forum], which has given us some funding that will support a retreat of the maintainers and a development sprint that will take place at the end of March. We meant to announce the retreat and sprint for some time now, but the size and publicity of the event may depend on updates to the various governmental and institutional recommendation in regards to COVID-19 spreading. If a public event will be possible, we will make a separate announce on this forum. We want to also thank all the contributors for the increasing number of comments, fixes and discussions that are helping us shape the next releases of owl. The Owl Dev Team [enormous amount of work] [ocaml.xyz ] [owl book] [OCaml Software Foundation] [announcement made on this forum] Parser combinators vs. parser preprocessors? =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90= =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90 Archive: Continuing this thread, yallop said =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80= =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80 Gasche said: Combinators also describe a grammar; they can build a representation that is then processed. I think it would be perfectly reasonable to provide combinators to describe a L(AL)R grammar, and then a function from such a grammar to a parsing automaton, along with the result of various analyses. This would solve the =E2=80=9Cadditional tooling=E2=80=9D problem of typical parser generators, and also the =E2=80=9Clack of conflict analysis=E2=80=9D problem of typical parser combinator libraries. But it may require support for staging for performance reasons. Readers of this thread may be interested in the [asp] (*algebraic staged parsing*) library (also described in the [Transept post] linked above), which is built on an approach along the lines @gasche describes: =E2=80=A2 combinators that describe a grammar (using context-free express= ions) =E2=80=A2 an analysis (formulated as a type system) that ensures determin= istic parsing =E2=80=A2 staging to eliminate performance overhead The interface is pretty standard, with combinators for alternation, sequencing, etc., and performance is quite good (better than `ocamlyacc' on our benchmarks). There's a paper, [A typed algebraic approach to parsing], that describes the design in more detail. Chet_Murthy said: Also, I=E2=80=99m personally a massive LL(1) (over LALR) bigot Grammars built using `asp' are essentially LL(1). (The weasel word "essentially" isn't hiding much here, but the paper has the details.) [asp] [Transept post] [A typed algebraic approach to parsing] Dune 2.4.0 =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90 Archive: Rudi Grinberg announced =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 On behalf of the dune team, I'm pleased to announce the release of dune 2.4.0. This releases features support for [mdx], an interesting take on the notebook paradigm by the RWO team. This release also includes a crucial fix to polling mode which makes it usable in environments with finite memory :slight_smile:. Happy hacking! [mdx] 2.4.0 (06/03/2020) =E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2= =95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95=8C=E2=95= =8C=E2=95=8C =E2=80=A2 Add `mdx' extension and stanza version 0.1 (#3094, @NathanReb) =E2=80=A2 Allow to make Odoc warnings fatal. This is configured from the = `(env ...)' stanza. (#3029, @Julow) =E2=80=A2 Fix separate compilation of JS when findlib is not installed. (#3177, @nojb) =E2=80=A2 Add a `dune describe' command to obtain the topology of a dune workspace, for projects such as ROTOR. (#3128, @diml) =E2=80=A2 Add `plugin' linking mode for executables and the `(embed_in_plugin_libraries ...)' field. (#3141, @nojb) =E2=80=A2 Add an `%{ext_plugin}' variable (#3141, @nojb) =E2=80=A2 Dune will no longer build shared objects for stubs if `supports_shared_libraries' is false (#3225, fixes #3222, @rgrinberg) =E2=80=A2 Fix a memory leak in the file-watching mode (`dune build -w') (#3220, @snowleopard and @aalekseyev) Tyxml 4.4.0 =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90 Archive: Gabriel Radanne announced =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80 I have the pleasure to announce the release of [TyXML 4.4.0], with special Reason support! [TyXML] is a library for building statically correct HTML and SVG documents. TyXML provides a set of combinators which use the OCaml type system to ensure the validity of the HTML. TyXML is now a stable library and this release comes with a few newly supported elements and attributes (such as ARIA elements) and associated bug fixes. However, the main novelty of this release is a long awaited feature: the support for [Reason=E2=80=99s JSX syntax] in the brand new `tyxml-jsx' package. See the complete announcement for code examples and details: [TyXML 4.4.0] [TyXML] [Reason=E2=80=99s JSX syntax] first release of oplsr: an OCaml wrapper to the pls R package - Partial Lea= st Squares (PLS) regression =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90= =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90= =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90= =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2= =95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95= =90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90= =E2=95=90=E2=95=90 Archive: UnixJunkie announced =E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2= =94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80 It is my great pleasure to release one more hackish wrapper to use some R package from within OCaml: For some background: Cf. test.ml in the sources for a usage example. Old CWN =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90 If you happen to miss a CWN, you can [send me a message] and I'll mail it to you, or go take a look at [the archive] or the [RSS feed of the archives]. If you also wish to receive it every week by mail, you may subscribe [online]. [Alan Schmitt] [send me a message] [the archive] [RSS feed of the archives] [online] [Alan Schmitt] --=-=-= Content-Type: text/html; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable OCaml Weekly News

OCaml Weekly News

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Hello

Here is the latest OCaml Weekly News, for the week of March 03 to 10, 2020.

Non opam workflows

Archive: = https://discuss.ocaml.org/t/non-opam-workflows/5232/1

Manas asked

Very recently, I learnt that there is a significant chunk of users in the O= Caml community that does not use opam to install packages. As a small initi= ative to contribute to tooling, I want to ensure what I build is compatible with = these workflows - workflows I'm not familiar with myself.

I'd love to learn more - what does it look like? How do you setup your comp= iler, dune and merlin (and/or soon ocamllsp)? How do you configure your edi= tor to find them and what would make it easier to do so?

I'm told of Duniverse as one tool that being used in these non-opam workflo= ws. Are there any more popular ones out there?

Th=C3=A9o Zimmermann replied

I am one of these people. I mostly rely on Nix, whose package repository ni= xpkgs provides package sets for all (relatively recent) versions of OCaml. = These package sets are not generally as complete as what you can find on opam, so= it sometimes happens that I open a PR on the nixpkgs repository to add a n= ew package (and in the meantime I use my local updated copy of the nixpkgs rep= o).

You can see the list of available OCaml packages at: https://nixos.org/nixos/packages.html?channel=3Dnixpkgs-unstable&= query=3DocamlPackages (This is for the default OCaml version, currently 4.07 in nixpkgs-unstable.= Other package sets are called ocaml-ng.ocamlPackages_4_0X but= are not shown in this web search.)

Most OCaml packages are available at a single version in nixpkgs (even thou= gh you can choose your version of OCaml). To gain more flexibility on the e= xact version I use in one of my project, I am planning to test Duniverse. At tha= t point, I would rely on Duniverse for library dependencies, but I would st= ill rely on Nix to install OCaml, findlib, Dune, Duniverse (I'll have to take c= are of packaging it), utop, merlin, or ocamlformat.

Nix is pretty straightforward to use. You generally provide a default= .nix at the root of your repository, and it will list the dependenci= es that you use. When you want to go develop your project, you just enter a special shell (w= ith the nix-shell command) and you are in an environment where= the tools you need are in PATH and the libraries you need are in OCAML= PATH.

There's just one tool that I needed special configuration for: ocamlf= ormat (especially because some projects use it and some do not). Whe= n I use it, my default.nix contains: 

shellHook =3D ''
  export OCAMLFORMAT_LOCATION=3D${ocamlformat}
'';

which will export an environment variable when I enter the shell.

And my .emacs contains: 

(setq ocamlformat-location (getenv "OCAMLFORM=
AT_LOCATION"))
(when (> (length ocamlformat-loca=
tion) 0)
 (add-to-list 'load-path (concat ocamlformat-location "/share/emacs/site-lisp"))
 (require 'ocamlformat)
 (add-hook 'tuareg-mode-hook
           (lambda () (add-hook 'bef=
ore-save-hook 'ocamlformat-before-save))))

I want to ensure what I build is compatible with these workflows

If you mean as a library author, then all you have to ensure is that you us= e Dune as the build system (makes the Duniverse workflow better, and makes = it easier to package your library in nixpkgs, cf. buildDunePackage documented at https://nixos.org/nixpkgs/manual/#sec-language-ocaml).

Rwmjones also replied

You might want to check out the Fedora OCaml packages.

Unfortunately I don't have a convenient way to link to the whole list, but = if you look at all the OCaml packages here: https://koji.fedoraproject.org/koji/search?ma= tch=3Dglob&type=3Dpackage&terms=3Docaml* and then if you substi= tute the ocaml-<packagename> in two places in this URL: https://src.fedoraproject.org/rpms/ocaml-re/blob/master/f/oca= ml-re.spec (example showing ocaml-re package), you can see= how we build and package them in the %prep, %build and %install se= ctions.

And yes, please make sure your software doesn't depend on opam. Building e= verything in your home directory is not suitable for enterprise software distribution.

First release of metapp

Archive: https://discuss.ocaml.org/t/ann-first-release-of-metapp/5250/1

Thierry Martinez announced

I am happy to announce the first release of metapp, yet anothe= r preprocessor for OCaml. Similarly to ppx_optcomp, metapp is a P= PX rewriter. But instead of introducing a specific DSL for preprocessor di= rectives, metapp provides a [%meta ...] extension= , where the dots ... are arbitrary OCaml expressions that are = substituted at compile-time by the AST nodes they evaluate into. These expr= essions build AST nodes either by (anti-)quoting some code directly, or by = using compiler-libs (Parsetree, Ast_helper, …).

In particular, this preprocessor is easy to use for conditional compilation= , and is an alternative to cppo and ppx_optcomp. 

let option_get o =3D
  [%meta =
if S=
ys.ocaml_version >=3D "4.08.0" then
     [%e Option.get o]
  else
     [%e match o with
     | None -> invalid_arg "option_get"
     | Some x -> x]]

In this example, the code between [%e ... ] is "anti-quoted": = it is the code that is inserted (conditionally) in the rewritten module. O= f course, the anti-quoted code can contain itself some [%meta ...] code. [%meta ...] can even itself contain other levels of [%meta = ...] code for multi-stage programming.

An example of usage of metapp is the metaquot package, which im= plements the same quoters as ppx_tools.metaquot: [%expr = ...], [%type: ...], etc. These quoters are implemented by meta-programming: the meta-code introspect= s Parsetree.cmi from compiler-libs to generate th= e code matching the current OCaml version.

Rapha=C3=ABl Proust added

To potentially save a few second to the next readers: https://github.com/thierry-martinez/metap= p seems to be the repo where it is hosted.

Thierry Martinez then said

Thanks, @raphael-proust! The package is also available via opam: opam= install metapp (and metaquot is available via opam as = well).

OCaml 4.10 released

Archive: https://discuss.ocaml.org/t/ocaml-4-10-released/5194/5

octachron continued this thread

The Merlin team has just released a preview version of Merlin which is comp= atible with 4.10.0 (Merlin is an editor service that provides modern IDE features for OCaml) .

This is a preview version:

  • the support for short-path is disabled
  • only OCaml 4.10.0 is supported in this preview

It can be installed via opam with the usual 

opam install merlin

Transept 0.1.0: Generalised Parser Combinators

Archive: https://discuss.ocaml.org/t/ann-transept-0-1= -0-generalised-parser-combinators/5262/1

Didier Plaindoux announced

I=E2=80=99m happy to announce the first release of Transept an OCaml implem= entation of generalized parsers combinators.

This implementation has been inspired by a 19 years old paper - written by = Daan Leijen and Erik Meijer - titled =E2=80=9CParsec: Direct Style Monadic = Parser Combinators For The Real World=E2=80=9D [1]. The current implementation pro= vides basic combinators dedicated to char, chars recognition but also conju= nction, sequence, repetition and more. Since the current design relies on the abstr= act definition of manipulated element most of the parsers are generic and c= an be used with streams of chars or something else.

Finally, with this library, I wanted to share my love of OCaml modules =F0= =9F=A4=97

Opam: = https://opam.ocaml.org/packages/transept/transept.0.1.0/

[1] https://www.microsoft.com/en-us/research/w= p-content/uploads/2016/02/parsec-paper-letter.pdf

Didier Wenzek then said

It good to see yet another parser combinator for OCaml, even if this makes = more difficult the choice of one of them. I believe this highlights how wel= l OCaml shines for this kind of applications where both high-level expressiveness a= nd performance matter.

angstrom= is one the alternatives and provides a comparison with others. It woul= d be good to position transept here.

There is also a more recent article with a radically new approach: A Typed, Algebraic Approac= h to Parsing by Neelakantan R. Krishnaswami and Jeremy Yallop - PLDI 2019. This paper propo= ses a library of parser co= mbinators for context-free expressions, an algebraic presentation of the context-free lan= guages. The key points are

  • the use of types to statically reject any language which cannot be pars= ed unambiguously and linearly;
  • the use of staging, with OcamlBER, to produce parsers which performance= are close to those of hand-written code.

Multicore OCaml: Feb 2020 update

Archive: https://discuss.ocaml.org/t/multicore-ocaml-feb-2020-update/52= 27/3

Continuing this thread, Rwmjones asked

Hi Anil (or anyone!). Is there a place I can find more about breaking chan= ges that might be made to C extensions? As you may know we have a lot of C= code which interfaces with OCaml, both as ordinary extensions written in C, but = also embedding OCaml in C programs (although that's much more rare), and I'= d like a heads up about what's likely to change.

Anil Madhavapeddy replied

Hi @rwmjones! In a nutshell: no breaking C changes. The longer version is t= hat we implemented two different minor collectors in order to evaluate vari= ous tradeoffs systematically:

  • a concurrent minor collector that requires a read barrier and some C AP= I changes in order to create more safe points
  • a stop-the-world minor collector that doesn't require a read barrier an= d no extra C API changes, but would probably cause longer pauses

The good news is that our STW collector scales up much better than we expec= ted (tested to 24 cores), and so our first domains patchset will almost cer= tainly use that version now. We expect to shift to a concurrent (and possibly pau= seless) collection algorithm at some future point, but in terms of upstream= ing it looks like we should be able to delay any C API changes until after the fir= st version of multicore has landed.

Do you have any nice standalone candidate programs using the C FFI we could= add to Sandmark?

owl 0.8.0 and 0.9.0 released

Archive: https://discuss.ocaml.org/t/ann-owl-0-8-0-and-0-9-0-released/= 5281/1

Marcello Seri announced

We are happy to announce two new releases of owl: a ded= icated system for scientific and engineering computing in OCaml.

Since our previous announcement in July last year, there has been an enormous amount= of work going on to cleanup and extend owl's internals and its interfaces.

In this period we have been trying to release often and keep disruption to = a minimum. Owl 0.8.0 and 0.9.0 are exceptional in this respect:

  • owl.0.8.0:

    • the discrepancy between owl-base (pure ocaml) and owl (links cblas/lapacke) interfaces started becoming a problem in few pla= ces. In this release many interfaces have been unified and reused. The algo= diff module has undergone a similar refactoring. Although most users should= be shielded from these changes, they may break existing code, requiring an= upper bound on owl and some localized updates. This should mostly boil dow= n to changes like 

      -module CGraph_D =3D Owl_comp=
utation_engine.Make_Graph (Owl_computation_cpu_device.Make (Dense.Ndarray.D=
))
+module CGraph_D =3D Owl_computation_engine.Make_Graph (Owl_computation_cpu=
_device.Make (Owl_algodiff_primal_ops.D))
    • this is the last edition supporting OCaml compiler versions < 4.10.0= (more on this later).
  • owl.0.9.0: the main difference between 0.8.0 = and 0.9.0 is that owl now requires OCaml 4.10.0. This release = of OCaml introduces extended indexing operators. With them we can no= w write things like x.%{0;3} (for indexing) and x.${[0:2= ];[2;4]} (for slicing) instead of the more cumbersome x.%{[|0;= 3|]} and x.${[[0:2];[2;4]]}.

The project is thoroughly documented at ocaml.= xyz where you can find multiple examples of use.

A lot of work has (and is) been going into improving the documentation, you= can find the results in the new owl book: https://ocaml.xyz/book/toc.html= . This is currently targeting the development version of owl, so using = master or 0.9.0 is the best bet if you want to try the examples out.

One of the issue of the old documentation was that it was getting stale ver= y fast: the book is reusing some of the infrastructure of RWO, so all examp= les get recompiled and retested continuously to ensure their correctness.

As a final note, we would like to send a huge thank to the OCaml Software Foundation, see also the announceme= nt made on this forum, which has given us some funding that will support a retreat of t= he maintainers and a development sprint that will take place at the end of March.

We meant to announce the retreat and sprint for some time now, but the size= and publicity of the event may depend on updates to the various government= al and institutional recommendation in regards to COVID-19 spreading. If a public event will be possible, we will make a separate announce on thi= s forum.

We want to also thank all the contributors for the increasing number of com= ments, fixes and discussions that are helping us shape the next releases of= owl.

The Owl Dev Team

Parser combinators vs. parser preprocessors?

Archive: https://discuss.ocaml.org/t/parser-combinators-vs-p= arser-preprocessors/5263/4

Continuing this thread, yallop said

Gasche said:

Combinators also describe a grammar; they can build a representation that i= s then processed. I think it would be perfectly reasonable to provide combi= nators to describe a L(AL)R grammar, and then a function from such a grammar to a = parsing automaton, along with the result of various analyses. This would so= lve the =E2=80=9Cadditional tooling=E2=80=9D problem of typical parser generators, = and also the =E2=80=9Clack of conflict analysis=E2=80=9D problem of typical= parser combinator libraries. But it may require support for staging for performance reasons.

Readers of this thread may be interested in the asp (algebraic staged parsing) library (al= so described in the Transept post linked above), which is built on an a= pproach along the lines @gasche describes:

  • combinators that describe a grammar (using context-free expressions)
  • an analysis (formulated as a type system) that ensures deterministic pa= rsing
  • staging to eliminate performance overhead

The interface is pretty standard, with combinators for alternation, sequenc= ing, etc., and performance is quite good (better than ocamlyacc on our benchmarks).

There's a paper, A typed algebraic approach to parsing, that describes the design in more detail.

Chet_Murthy said:

Also, I=E2=80=99m personally a massive LL(1) (over LALR) bigot

Grammars built using asp are essentially LL(1). (The weasel w= ord "essentially" isn't hiding much here, but the paper has the details.)

Dune 2.4.0

Archive: http= s://discuss.ocaml.org/t/ann-dune-2-4-0/5288/1

Rudi Grinberg announced

On behalf of the dune team, I'm pleased to announce the release of dune 2.4= .0. This releases features support for mdx, an interesting t= ake on the notebook paradigm by the RWO team. This release also includes a = crucial fix to polling mode which makes it usable in environments with finite memory :slig= ht_smile:.

Happy hacking!

2.4.0 (06/03/2020)

  • Add mdx extension and stanza version 0.1 (#3094, @NathanRe= b)
  • Allow to make Odoc warnings fatal. This is configured from the (e= nv ...) stanza. (#3029, @Julow)
  • Fix separate compilation of JS when findlib is not installed. (#3177, @= nojb)
  • Add a dune describe command to obtain the topology of a du= ne workspace, for projects such as ROTOR. (#3128, @diml)
  • Add plugin linking mode for executables and the (emb= ed_in_plugin_libraries ...) field. (#3141, @nojb)
  • Add an %{ext_plugin} variable (#3141, @nojb)
  • Dune will no longer build shared objects for stubs if supports_shared_libraries is false (#3225, fixes #3222, @rgrin= berg)
  • Fix a memory leak in the file-watching mode (dune build -w) (#3220, @snowleopard and @aalekseyev)

Tyxml 4.4.0

Archive: htt= ps://discuss.ocaml.org/t/ann-tyxml-4-4-0/5290/1

Gabriel Radanne announced

I have the pleasure to announce the release of TyXML 4.4.0, with special Reason su= pport!

TyXML is a library for bui= lding statically correct HTML and SVG documents. TyXML provides a set of co= mbinators which use the OCaml type system to ensure the validity of the HTML. TyXML is now a st= able library and this release comes with a few newly supported elements and attributes (such as ARIA elements) and associated bug fixes. However, the m= ain novelty of this release is a long awaited feature: the support for Reason=E2=80=99s JSX syntax in the brand new tyxml-jsx package.

See the complete announcement for code examples and details: https://drup.github.io/2020/03/06= /tyxml440/

first release of oplsr: an OCaml wrapper to the pls R package= - Partial Least Squares (PLS) regression

Archive: https://discuss.ocaml.org/t/ann-first-release-of-oplsr-an-ocaml-wra= pper-to-the-pls-r-package-partial-least-squares-pls-regression/5293/1

UnixJunkie announced

It is my great pleasure to release one more hackish wrapper to use some R package from within OCaml:

https://github.com/UnixJunk= ie/oplsr

For some background: = https://en.wikipedia.org/wiki/Partial_least_squares_regression

Cf. test.ml in the sources for a usage example.

Old CWN

If you happen to miss a CWN, you can send me a message and I'll mail it to you, or go take a loo= k at the archive or the RSS feed of the archives<= /a>.

If you also wish to receive it every week by mail, you may subscribe online.

Alan Schmitt

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