OCaml Weekly News

Hello

Here is the latest OCaml Weekly News, for the week of July 23 to 30, 2024.

.mlx syntax dialect

Archive: https://discuss.ocaml.org/t/ann-mlx-syntax-dialect/15035/1

Andrey Popp announced

Dear OCaml community,

it is my pleasure to announce a release of .mlx dialect.

The .mlx dialect extends OCaml syntax with JSX expression construct, follow= ing the example of JSX in JavaScript/ReasonML. A brief snippet:

let page ?(encoding=3D"utf=
8") ~title ~content =3D
  <html>
    <head>
      <meta charset=3Dencoding />
      <title>title</title>
    </head>
    <body>
      content
    </body>
  </html>

let _ =3D <page title=3D"Hello" content=3D"World" />

The main use case is to make it easier to describe user interfaces with OCa= ml, which can range from generating HTML (example with Dream) or describing interactive UIs with ReasonRea= ct (example).

Installation and usage

Install the packages from opam:

opam install mlx ocamlmerlin-mlx

Then configure dune to use the mlx preprocessor:

(dialect
 (name mlx)
 (implementation
  (extension mlx)
  (merlin_reader mlx)
  (preprocess
   (run mlx-pp %{input-file}))))

Now files with .mlx extension will be treated as OCaml modules.

The merlin/ocamllsp users will get roughly the same level of support for .mlx syntax as they get for .ml but some additional= text editor/IDE configuration is needed to associate .mlx fil= es with merlin/ocamllsp.

For neovim users there's a plugin ocaml-mlx/ocaml_mlx.nvim, which does that bit of a confi= guration and provides highlighting for .mlx files based on a t= ree-sitter parser.

heml, a HEEx-inspired HTML templating ppx for OCaml

Archive: https://discuss.ocaml.org/t/ann-heml-a= -heex-inspired-html-templating-ppx-for-ocaml/15037/1

Petri-Johan Last announced

I've been working on heml, a= PPX extension that allows you to build complex HTML templates directly in = your OCaml code.

It's a direct implementation of Elixir Phoenix's HEEx templates.

The README on GitHub has an example video of what it looks like in the edit= or and a bunch of example code, but here's a short snippet for convenience:

(* layouts=
.ml *)
let layout ~title contents =3D {%heml|<!DOCTYPE htm=
l>
<html lang=3D"en">
  <head><title><%s=3D=
 title %></title></head&=
gt;
  <body>
    <%raw=3D contents %>
  </body>
</html>|}

(* main.ml *)
let heading ~text =3D {%heml|<h1><%s=
=3D text %></h1>|}

let greet ~user =3D {%heml|<p>Hello, <%s=3D u=
ser %></p>|}

let () =3D
  let title =3D "Hell=
o, OCaml!" in
  print_endline {%heml|<Layouts.layout title=3D{title}>
    <.heading text=3D"Hello!" /&g=
t;

    <%=3D List.iter (fun user -> %>
      <.greet user=3D{user} />
    <%=3D ) ["Steve"; "Becca";=
 "John"]; %>

</Layouts.layout>|}

heml differs from other templating solutions by allowing you to call OCaml = code directly in the template, which is extremely useful for looping and co= nditional rendering. You can also create and call your own components/layou= ts.

heml leverages the OCaml LSP for accurate in-line errors, and the templates= are parsed and compiled into a series of Buffer writes which returns a str= ing at runtime.

I'm still waiting for it to be released on opam, but thought I'd share it in the m= eantime in case anyone would be willing to check it out and provide feedbac= k :slight_smile: .

Forester 4.2

Archive: h= ttps://discuss.ocaml.org/t/ann-forester-4-2/15043/1

Jon Sterling announced

I am pleased to announce the release of Forester 4.2 on opam, which is an O= Caml utility to develop =E2=80=9CForests=E2=80=9D, which are densely interl= inked mathematical websites / Zettelk=C3=A4sten similar to the Stacks project or Kerodon. You can see the changelog on my own Forest.

This release adds many new features and improvements, including:

First-class functions and lazy arguments, which can be used to implemen= t more ergonomic MathML macros.
A new query language, which is now expressive enough to encode the back= matter
Improved performance of graph analysis (2x overall speedup rendering my= own forest)

To see other features and documentation of breaking changes, please view th= e Forester 4.2 Release= Notes.

My thanks to @kentookura and Jinser Kafka for their contributions to this r= elease.

First Robotics and OCaml - Do you know any local teams?

Archive: https://discuss.ocaml.org/t/first-roboti= cs-and-ocaml-do-you-know-any-local-teams/15051/1

jbeckford announced

For those who don't know, First Robotics is a competitive, international hi= gh school league for robotics: https://www.firstinspires.org/robotics/frc.

I've helped a couple students write "scouting" software partially in OCaml = and partially in Java: https://github.com/diskuv/scout= apps/tree/main?tab=3Dreadme-ov-file#sonic-scout-apps

It is a very very slow season for robotics teams, but if your local = high school participates now is a great time for the mentors of that team t= o get ready. If you know a team that needs scouting software and want to he= lp spread OCaml to your local neighborhoods … please direct message = me.

2nd editor tooling dev-meeting: 25th of July =F0=9F=A7=99

Archive: https://discuss.ocaml.org/t/ann-2nd-editor-to= oling-dev-meeting-25th-of-july/14953/4

Continuing this thread, vds announced

Thanks a lot to all participants and speakers, it was a very nice and inter= esting meeting !

You can find the meeting notes here: https://github.com/ocaml/merlin/wiki= /Public-dev%E2%80%90meetings

With the summer (/winter) break coming for a lot of us, the next meeting wi= ll take place in September. We will implement a call-for-presentation and a= poll to choose meeting times by then.

Don't hesitate to tell us right away if you would like to give a presentati= on or if you have subjects that you would like us to take on. (@andreypopp = would you be interested in talking about melange and how it integrates with= editor tooling ?)

Other OCaml News

From the ocaml.org blog

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

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