OCaml Weekly News

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Here is the latest OCaml Weekly News, for the week of May 14 to 21, 2024.

We Want Your Feedback on the odoc Developer Experience

We Want Your Feedback on the odoc Developer Experience

Archive: https://discuss.ocaml.org/t/we-want-yo= ur-feedback-on-the-odoc-developer-experience/14646/1

Sabine Schmaltz announced

Hey all, =F0=9F=A7=A1=F0=9F=90=AB

the documentation team at Tarides is lo= oking for input and feedback on odoc.

I would be super happy if everyone who uses odoc or would use odoc if it wo= rked for them can drop an answer in this feedback form:

https://docs.google.com/= forms/d/e/1FAIpQLSfpZHlnbQjWolAhKJvn41aT5QJc7Gb7uZJSdtTT7MZeAdyMow/viewform= ?usp=3Dsf_link

Windows compiler support in opam 2.2.0~beta2

Archive: https://discuss.ocaml.org/t/windows-compiler-sup= port-in-opam-2-2-0-beta2/14648/1

David Allsopp announced

On behalf of the entire opam team, but also with a personal sense of relief= , I'm very pleased to announce that the process of upstreaming support for = Windows OCaml to opam-repository in ocaml/opam-repository#25861 finally started on= Friday!

There's a full = blog post with details on how you can try this out now with opam 2.2.0~= beta2. The TL;DR, assuming you have winget on your Windows system (open the= Microsoft Store app and install the App Installer package from Microsoft if you don't)= then you can issue:

winget install Git.Git

if you don't have Git for Windows and:

winget install opam

if you don't yet have the 2.2.0~beta2 binary. You must then launch a fre= sh Command Prompt / PowerShell session. For there, you can then run:

opam init git+https://github.com/dra27/opam-repository.git#windows-initial

opam init -a --no-git-location --cygwin-internal-install git+https://github=
.com/dra27/opam-repository.git#windows-initial

if you'd like to be asked fewer questions. There is a known and big paus= e when updating the repository. However, after a little bit of time (co= ffee, or a sword battle, if that's yo= ur thing), you should then be faced with a fully initialised opam with ocam= l-base-compiler.5.2.0 installed for the mingw-w64 amd64 port of native Wind= ows opam.

Things with depexts will likely not work: the blog post contains details on= how to get started with PRs, but issues are also helpful.

The blog post covers what we regard as the "default use case" - that is a n= ative Windows user expecting to use this new OCaml thing they heard about n= atively. i.e. not running in WSL or Cygwin or MSYS2 or any other "are you s= ure can't just install Linux on that?" approach.

However, all the other use cases matter too! You're meant to be able to run= native Windows opam from your own Cygwin or MSYS2 mintty bash terminal; we= are aiming for the opam 2.2.0 binary to be a drop-in replacement (apart fr= om setting os-distribution to "cygwinports") for = "OCaml for Windows" for legacy use with the "sunset" repository; you're meant to b= e able to provide your own Cygwin or MSYS2 installation if you really need = to (and you really might!). But we do need help testing all of it =F0=9F=99= =82

We anticipate one further beta of opam 2.2.0 by the end of the month. From = the Windows perspective, this will fix a known bug in the environment varia= ble handling (see oca= ml/opam#5838) but will also hopefully straighten out the behaviour of <= code>opam init for some of these "non-default" use cases. We're then= hoping to rocket towards a release candidate in June =F0=9F=9A=80

Happy Windows hacking! Please open issues; please ask for further help; ple= ase have fun!

David, on behalf of the opam team.

OCaml Workshop 2024 at ICFP – announcement and call for= proposals

Archive: https://discuss.ocaml.org/t/o= caml-workshop-2024-at-icfp-announcement-and-call-for-proposals/14371/6

Continuing this thread, Sonja Heinze said

One more update, this time about hybrid modalities: We now have the confirm= ation from sigplan (the organizers behind ICFP) that we'll have the same hy= brid modalities as last year :tada: So in particular, speakers can give tal= ks remotely via a Zoom call. We'll also make sure this time that the remote= speaker can see the audience over the call. To promote a good atmosphere, = communication and engagement, we do prefer to have most talks in-person, bu= t remote talks will be most welcome as well. So, don't hesitate to submit a= talk even if you can't make it in person.

Cheers, @Arma=C3=ABl and @pitag

PD: Once the time comes closer, we'll give detail on youtube live and disco= rd links for remote attendance as well

Guillaume Munch-Maccagnoni then added

Thanks, this update about hybridity should also be true for the ML workshop.

Odoc syntax cheatsheet

Archive: https://discuss.ocaml.org/t/ann-odoc-syntax-cheatsheet/14658/1

Paul-Elliot announced

Hello!

I'm happy to announce the addition of a cheatsheet for odoc's syntax!

I hope it will make it less painful to learn or refresh yourself on the top= ic. The full= syntax reference is still useful to have some details.

Have {b fun} :slight_smile: !

DkCoder 0.2 - Scripting in OCaml

Archive: https://discuss.ocaml.org/t/dkcoder-0-2-scripting-in-ocaml/145= 60/2

jbeckford announced

The 0.3 version is now available. It has a publicly accessible https://github.com/diskuv/dkcoder so = issues can be filed, and cohttp 6.0.0~beta2 is now bundled.

Most important, 0.3 was sufficient to build the real production service https:= //gitlab.com/diskuv/samples/devops/DkSubscribeWebhook. It has a Dockerf= ile and Docker Compose for easy deployment to production, and the Docker co= ntainer is based on Google's https://github.com/GoogleContainerTools/distroless#= readme for a "small" size (well, 100MB is not small but it is not big e= ither). The only executable in the container is ocamlrunx (no = /bin/sh, etc.). In an ideal world where I had more time the se= rvice would be embedded inside MirageOS instead.

Imandra SysML Transpiler Internship Opportunity!

Archive: https://discuss.ocaml.org/t/imandra-sysml-tra= nspiler-internship-opportunity/14660/1

Ben Bellick announced

I wanted to share an opportunity for a summer internship with Imandra!

If you're someone with an interest in writing production OCaml or using a b= attle-worn automated theorem prover in an industry setting, please apply!

It is based in Austin, TX.=20

You can find more details and apply here.=20

Thanks!

Bam - A property-based testing with internal shrinking

Archive: https://discuss.ocaml.org/t/ann-bam-= a-property-based-testing-with-internal-shrinking/14661/1

Fran=C3=A7ois Thir=C3=A9 announced

I am excited to introduce Bam, a robust and versatile property-based= testing (PBT) library. Bam simplifies the process of testing properties ac= ross a wide range of randomly generated values, making it easier to identif= y and debug issues in your code.

Key Features

Monad-like Generators: Create new generators easily with a monad= -like pattern that works seamlessly with shrinking mechanisms.
PPX Support: Automatically derive generators based on type descr= iptions. The customizable deriver ensures smooth integration into your code= base.
Tezt Integration: Integrates with the Tezt test framework, provi= ding a user-friendly experience, especially notable in debugging scenarios.=
Internal Shrinking: Various default shrinking strategies help ef= ficiently pinpoint minimal counterexamples. Internal shrinking ensures that= only 'smaller' values are used during the process, and this is done in a w= ay that is compatible with the monad-like operators.
Custom Shrinking: Define custom shrinkers that work well with th= e existing shrinking strategies.

Installation

You can install Bam using opam:

opam install bam tezt-bam

Getting started

Here is an example to get you started:

open Tezt_bam

type t =3D Foo of {a: int; b: string} | Bar of int list [@@deriving gen]=

(** The deriver creates=
 a value [val =
gen : t Bam.Std.t]. *)

let register () =3D
  let property =3D function
    | Foo=
 {a; b} ->
        if a >=
 1_000 && String.contains b 'z'<=
/span> then
          Error<=
/span> (`Fail "A counter-example was found")
        else Ok ()
    | Bar=
 [1; 2; 3; 4] ->
        Error `Bad_value<=
/span>
    | Bar=
 _ ->
        Ok ()
  in=20=20
  Pbt.register ~__FILE__ ~title:<=
span style=3D"color: #ca3400;">"Simple example of bam" ~tags:["bam"; "simple"]
    ~gen ~property ()

let _ =3D=20
    register ();
    Test.run ()

There are several more detailed examples in the repository to show you around= the library.

Contributions

Contributions from the community are welcome! If you have ideas, bug report= s, or improvements, feel free to share them!

Kakadu asked and Fran=C3=A7ois Thir=C3=A9 replied

Can it be compared to https:/= /github.com/c-cube/qcheck/ ?

My work around Bam started after using "QCheck" and especially "QChe= ck2" quite a lot for the Tezos project.

With respect to QCheck, QCheck2 came with "integrated" shrinking allowing t= o derive automatically shrinkers for generators. This aim to simplify debugging when a counter-example is found, so that a smaller ex= ample is reported to the user.

However, this came with a cost:

Performance-wise, there was a regression from "QCheck", especially the = time taken to report a counter-example because the shrinking process was ta= king a lot of time
At some point, we even faced an issue were the shrinking process never = ended. We started to implement an ad-hoc shrinker but it was not working ei= ther and we never really figured out. The solution was to deactivate shrink= ing
There are other UX considerations: debugging can be tedious (especially= "hello" debugging)

So basically Bam started as an experiment to understand shrinking an= d come up with something easier to understand and compose better. This is why bam relies mainly on monadic operators.

This makes the writing of generators easier, the shrinking is internal ensuring the shrinking won't create new value. If you use the mondic operator of QCheck2, last time I checked it was not the case. Th= is is why to create a generator for a pair, it is recommended to use tup2 instead of monadic operators.

Using monadic-operators allows you also to have a smaller kernel that is ho= pefully easier to maintain.

I also developped the integration of bam with Tezt in a way to avoid= currently pitfalls we had with QCheck2:

You can easily control the stopping condition of the test

The test can be easily run in parallel or in a loop mode to help you fi= nd a counter-example quicker

The runner can fail if not enough values were generated or execution wa= s too long (likely due to a regression)

It captures the output, so that only the one for the counter-example pr= inted is shown. This is very handy during debugging. Otherwise, it is quite= tedious to understand which line comes from which attempt

It is easy to opt-out from shrinking if it takes too much time. Can be = useful for a CI. Shrinking only needs to be executed locally (assuming the = property is deterministic) with a given seed

I also had some fun trying to define shrinking strategies allowing you to s= kip elements in a list. This is very handy when your property is about running a scenario made of a list of actions (a use-case = very close to the monolith library from Fran=C3=A7ois Pottier). In general the initial counter-example contains superfluous actions. Such a= strategy allows you to remove them to easy the debugging.

I don't have concrete data to compare Bam with QCheck2 at the moment. Let m= e know if you have ideas to make an objective comparison between those two libraries.

Stitch - Note Managing for Unorganized Minimalists

Archive: https://discuss.ocaml.org/t/stitch-note-mana= ging-for-unorganized-minimalists/14664/1

Marc Coquand announced

Hey everyone!

I wanted to share a cli tool built in OCaml I've been working on, that was = only possible with the help of the community. :slight_smile:=20

The tool is called stitch, and is a minimal note-managing tool that aims to= be a good unix citizen. It allows you to take notes in whatever format/edi= tor you want while spending minimal time organizing them.

I built it using Cmdliner, Notty and Shexp. I'm drafting a longer writeup t= o share the challenges and general experience, but in short all three libra= ries were a bit short on examples but ultimately excellent and very easy to= work with. Afterward, packaging everything turned out to be a bit harder.

Some screenshots: overview, t= odo, fu= ll-notes.

And link to repo:

https://git.mccd.space= /pub/stitch/about/

It's still in it's early days and the code-base is a bit messy. But I use i= t as my daily driver for notes. :slight_smile:

7 OCaml Gotchas

Archive: https://discuss.ocaml.org/t/blog-7-ocaml-gotchas/14667/1

Dmitrii Kovanikov announced

Hi everyone! :wave:=20

I've been using OCaml for a while, and I'm quite enjoying the language. In = my not-so-long journey, I discovered a few surprising OCaml behaviours, so = I decided to share them with everyone in a blog post.

7 OCaml Gotcha= s

I hope it reduces frustration for newcomers when they see something unexpec= ted for the first time!

Using OCaml on windows with WSL

Archive: https://discuss.ocaml.org/t/blog-using-ocaml-on-windows-= with-wsl/14671/1

PizieDust announced

When I got started in OCaml, my setup was basically a dual boot of Windows = 11 and Ubuntu. I had a few issues setting up OCaml on windows at the time a= nd started looking up WSL and if it was a good alternative (I really dislik= ed having to dual boot always). So I wrote this article detailing exactly h= ow I setup OCaml on WSL and have been using it for the past 12 months with = no issues. So if you are looking to get started with programming in OCaml o= n windows, this article is for you.

How to setup OCaml on Windows with WSL

Note: opam 2.2 makes it a breeze using OCaml on windows natively so = if you are particularly interested about using OCaml without WSL you should= check it out.

Other OCaml News

From the ocaml.org blog

Here are links from many OCaml blogs aggregated at the ocaml.org blog.

The MirageOS re= treat 2024

The OCaml 5.2 Release: Features and Fixes!

Beta release of= Frama-C 29.0~beta (Copper)

Bye Opam,= Hello Nix

How to Setup OCaml on Windows with WSL

Announcing D= BCaml, Silo, Serde Postgres and a new driver for postgres

Fixing and Optimizing the GnuCOBOL Preprocessor

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 <= a href=3D"https://alan.petitepomme.net/cwn/cwn.rss">RSS feed of the archive= s.

If you also wish to receive it every week by mail, you may subscribe to the= caml-list.

Alan Schmitt

OCaml Weekly News

Table of Contents

We Want Your Feedback on the odoc Developer Experience

Sabine Schmaltz announced

Windows compiler support in opam 2.2.0~beta2

David Allsopp announced

OCaml Workshop 2024 at ICFP – announcement and call for= proposals

Continuing this thread, Sonja Heinze said

Guillaume Munch-Maccagnoni then added

Odoc syntax cheatsheet

Paul-Elliot announced

DkCoder 0.2 - Scripting in OCaml

jbeckford announced

Imandra SysML Transpiler Internship Opportunity!

Ben Bellick announced

Bam - A property-based testing with internal shrinking

Fran=C3=A7ois Thir=C3=A9 announced

Key Features

Installation

Getting started

Contributions

Kakadu asked and Fran=C3=A7ois Thir=C3=A9 replied

Stitch - Note Managing for Unorganized Minimalists

Marc Coquand announced

7 OCaml Gotchas

Dmitrii Kovanikov announced

Using OCaml on windows with WSL

PizieDust announced

Other OCaml News

From the ocaml.org blog

Old CWN