[Caml-list] Attn: Development Editor, Latest OCaml Weekly News

[Alan Schmitt <alan.schmitt@polytechnique.org>]

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Hello

Here is the latest OCaml Weekly News, for the week of September 06 to
13, 2022.

Table of Contents
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Caqti 1.9.0 and Plans for 2.0.0
Outreachy summer ’22 closing commemoration session on 23rd Sept
MirageOS for B2B SaaS
Tuareg and Caml modes for Emacs: what are the differences?
Engineer position at Imandra (Austin TX/UK)
Acme plumbing rules for OCaml
Other OCaml News
Old CWN


Caqti 1.9.0 and Plans for 2.0.0
═══════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/ann-caqti-1-9-0-and-plans-for-2-0-0/10448/1>


Petter A. Urkedal announced
───────────────────────────

  First I would like to announce the 1.9.0 minor release, see the
  release notes below for details.

  There is also ongoing work in the [caqti2 branch] targeted for the
  next major release. If someone have an opinion on directions, we can
  discuss it here, or in the issue tracker ([meta-issue]), see my brief
  notes below.

  I will attend parts of the ICFP 2022 virtually next week so there may
  be time to discuss over audio.


[caqti2 branch] <https://github.com/paurkedal/ocaml-caqti/tree/caqti2>

[meta-issue] <https://github.com/paurkedal/ocaml-caqti/issues/90>

Release Notes for 1.9.0
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

  New features:

  • Allow unquoted semicolons in query strings in the new API. There are
    corner cases where it is needed, as reported in issue #87, and a
    parser which rejects semicolons are still available for loading
    schema files statement by statement.

  • Add support for MySQL and MariaDB configuration files, as a solution
    to issue #86.

  • Add a limit to the number of times a database connection is reused
    when pooling connections (#94). Thanks to Peter Mondlock for
    investigating resource usage server side motivating this addition.

  • Provide access to the raw SQLite3 connection handle for the purpose
    of defining custom functions (#56).

  Fixes:

  • Add missing dune dependency on unix (GPR#85 by David Allsopp).

  • Documentation fixes (GPR#82, GPR#83, GPR#84 by Reynir Björnsson,
    GPR#88 by Jonathan Duarte, and GPR#92 by Jim Tittsler).

  Deprecations:

  • `Caqti_type.field' was deprecated in favour of `Caqti_type.Field.t'.

  Other:

  • Replace deprecated core_kernel dependency with core.


Notes on 2.0.0 Development
╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌

  The main addition is pgx and mirage support. It is already functional,
  but not very useful for production, since it lacks TLS. The trick here
  is that PostgreSQL uses STARTTLS, so we can’t use conduit-lwt as-is.

  Another thing in progress, but unpublished, is [per-connection
  configuration]. Up till now, configuration has only been possible
  through the connection URL or behind-the-scene via C libraries (now
  also for MariaDB). However, this will no longer be practical for
  delivering CA certificates to pgx. Two design issues which you may
  have an opinion about:

  • Driver specific options can be defined in the `caqti' package or in
    `caqti-driver-*' packages. In the former case, the configuration can
    be manipulated without depending on specific drivers, but the
    downside is that we will pull in dependencies on `x509',
    `domain-name', `ipaddr' and possibly `tls' and `sexplib0'.
  • My current sketch provides sexp-serialisation, a choice mainly
    motivated by the availability of such serialization for client
    configuration of `tls', but I hope to find a more generic solution
    which allows easy embedding of Caqti configuration in application
    configuration independent of which format is used.

  An example of how an sexp-formatted configuration might look like:
  ┌────
  │ (connection
  │  (pool
  │   (max-use-count 20)
  │   (max-idle-size 10))
  │  (driver postgresql)
  │  (endpoints
  │   (inet pg1.example.org)
  │   (inet pg2.example.org))
  │  (target-session-attrs read-write))
  └────
  where the `(pool ...)' clause is driver-indepnedent and the `(driver
  ...)' clause determines which DB-specific options are valid. In the
  current draft, order does not matter despite this dependency.

  (I could also mention plans of wrapping modules, but this will be done
  first as a forward-compatible module in parallel to the current
  modules preferably at the beginning of a major release cycle. The
  reason I haven’t written that main `Caqti' module yet, is that I would
  like to take the opportunity to tidy up the namespace to make it
  easier for newcomers to discover the main entry points.)


[per-connection configuration]
<https://github.com/paurkedal/ocaml-caqti/issues/89>


Outreachy summer ’22 closing commemoration session on 23rd Sept
═══════════════════════════════════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/outreachy-summer-22-closing-commemoration-session-on-23rd-sept/10450/1>


Moazzam Moriani announced
─────────────────────────

  I, along with Jay, were the two [Outreachy] interns working with the
  OCaml :camel: community this summer. I worked on [Multicore
  Applications] and Jay on [TopoJSON]. Our internship, of course, was
  only made possible because @sudha and @patricoferris generously chose
  to volunteer to mentor us–as our respective mentors–throughout the
  summer. We are grateful to the both of them :heart:.

  Our three-month long Outreachy internship just ended relatively
  recently and, personally, I have really enjoyed working on my project
  and learning OCaml. So much so that Jay and I would like to share our
  experiences with the rest of the community. :sparkles:

  To carry forward a tradition established by the [previous Outreachy
  cohort], we will host a virtual session that will consist of two short
  presentations from the both of us followed by a Q&A. The session will
  be on Friday 23rd September 2-3pm CET.

  It is open to whoever wishes to join. A recording will be shared later
  online as well.

  We hope you will join us! :raised_hands:


[Outreachy] <https://www.outreachy.org/>

[Multicore Applications] <https://github.com/ocaml-bench/sandmark>

[TopoJSON] <https://github.com/geocaml/ocaml-topojson>

[previous Outreachy cohort]
<https://discuss.ocaml.org/t/friday-03-04-intern-presentations-open-attendance/9429>


Marcus Rohrmoser asked and Moazzam Moriani replied
──────────────────────────────────────────────────

        I suppose you mean CEST i.e.
        2022-09-23T14:00:00+02:00/PT1H

  Yes I do. Thank you for pointing it out.


MirageOS for B2B SaaS
═════════════════════

  Archive: <https://discuss.ocaml.org/t/mirageos-for-b2b-saas/10454/1>


Volodymyr Melnyk asked
──────────────────────

  I have an idea to build a SaaS for corporate blogging (like Medium,
  but for companies) and I want to try MirageOS as a total platform for
  services. I have no production experience with OCaml (only Golang, JS,
  Ruby) and have no experience with MirageOS and unikernels (only
  Docker, Linux, and a little bit k8s), but I’m very interested in both.
  Could you please help me to clarify possible issues with such an
  approach?

  Also I’m interested about a hosting for MirageOS services. I don’t
  like containers and k8s stuff and I prefer dedicated and virtual
  servers instead of cloud stuff because I have no resources to pay up
  to 5x more for hosting.

  Thank you for your help!


Calascibetta Romain replied
───────────────────────────

  Thank you for your interest in MirageOS. MirageOS is first and
  foremost a framework for creating an application (such as a blog) for
  several targets. One of these targets is [Solo5] which allows to
  create an entire system which includes everything necessary for OCaml
  (its runtime). Thus, one can deploy a MirageOS application on:
  • KVM (with the target `hvt')
  • [Xen]
  • or produce a simple executable taking advantage of [seccomp] (and
    thus finely controlling access to the executable).
  • we can also mention the experimental target for [Raspberry Pi 4]

  The objective of MirageOS is to make the choice of targets transparent
  to the application. This means that for a given application, deploying
  for KVM or Xen should not be an upstream choice (which would govern
  the development of the application) but the last of the choices which
  can, of course, be left to third party users.

  This reverses the development logic of an application thanks to
  abstraction mechanisms (specific to OCaml) (the [functors]) that allow
  to get rid of any specialisation to a given system (Solo5, Unix,
  Raspberry Pi, etc.).

  This is of course the theory and in practice, it works quite well :) .

  To take the example of the blog, you can see [Hannes’ blog] or [mine]
  which runs on MirageOS (KVM). The latter have a similar architecture:
  a unikernel managing TLS certificates and redirecting HTTP connections
  to unikernels on a local network ([tlstunnel] or [contruno]) and a
  unikernel ([unipi]) that only transmits what appears in a Git
  repository via the HTTP protocol (http/1.1 and h2).

  Deployment depends of course on what you have. Regarding KVM, you can
  follow the tutorials [here] (quite general) and [there]. You can
  deploy your unikernels on Google Cloud with this (probably a bit old)
  [tutorial]. Finally, a deployment with seccomp is possible, it is a
  simple executable.

  Of course, most of these unikernels are already available for download
  [here] thanks to the excellent work of [robur.io]. It is ensured that
  the generated image is reproducible regardless of the context.

  There is of course a whole series of unikernels made by the community
  that you can mainly find on GitHub. We can talk about several services
  like [DNS] or [emails].

  I would like to specify that all this is still experimental. We are
  gradually reaching the stage where our unikernels are used in
  production domains, but it still requires a lot of work and a lot of
  skills for such a small team :) . Of course, we are open to everyone’s
  participation and we are especially here to help newcomers.


[Solo5] <https://github.com/Solo5/solo5/>

[Xen] <https://xenproject.org/>

[seccomp]
<https://code.google.com/archive/p/seccompsandbox/wikis/overview.wiki>

[Raspberry Pi 4] <https://github.com/dinosaure/gilbraltar/>

[functors] <https://ocaml.org/docs/functors>

[Hannes’ blog] <https://hannes.nqsb.io/>

[mine] <https://blog.osau.re>

[tlstunnel] <https://github.com/roburio/tlstunnel>

[contruno] <https://github.com/dinosaure/contruno>

[unipi] <https://github.com/roburio/unipi>

[here] <https://robur.coop/Projects/Reproducible_builds>

[there] <https://blog.osau.re/articles/blog_requiem.html>

[tutorial]
<https://github.com/aantron/dream/tree/master/example/w-mirage>

[here] <https://builds.robur.coop/>

[robur.io] <https://robur.io/>

[DNS] <https://github.com/roburio/dns-primary-git>

[emails] <https://mirage.io/blog/2022-04-01-Mr-MIME>


Tuareg and Caml modes for Emacs: what are the differences?
══════════════════════════════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/tuareg-and-caml-modes-for-emacs-what-are-the-differences/10285/12>


Deep in this thread, Tim McGilchrist announced
──────────────────────────────────────────────

  I wrote up a longer form version of my setup at
  <https://lambdafoo.com/posts/2022-09-07-ocaml-with-emacs-2022.html>
  There are still some bits I am not happy with but I have been using it
  daily. Also @bbatsov wrote his version at
  <https://batsov.com/articles/2022/08/23/setting-up-emacs-for-ocaml-development/>


Engineer position at Imandra (Austin TX/UK)
═══════════════════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/engineer-position-at-imandra-austin-tx-uk/10465/1>


Simon Cruanes announced
───────────────────────

  [Imandra] is looking for a full time engineer in the UK or in Austin,
  Texas.

  The job offers can be found [here].Imandra is an AI startup developing
  a cloud-native automated reasoning engine for analysis of algorithms
  and data. Whether you’re writing mission-critical code or need to
  understand the countless complex decisions that a system may make, use
  Imandra to ensure the algorithms you create are safe, explainable and
  fair. OCaml is the main language used at Imandra.


[Imandra] <https://imandra.ai/>

[here] <https://apply.workable.com/imandra/>


Acme plumbing rules for OCaml
═════════════════════════════

  Archive:
  <https://discuss.ocaml.org/t/acme-plumbing-rules-for-ocaml/10467/1>


David A. Arroyo announced
─────────────────────────

  I am sure that the intersection of OCaml users and [Acme] users is
  small, but I have reason to believe it is a non-zero set :) . For
  those of you using this spartan editor, here are some plumbing rules
  that I use that allow me to right-click on error messages returned by
  the OCaml compilers, and jump to the referenced location in acme:

  ┌────
  │ # example: in file "foo/bar.ml", line 155, characters 30-62
  │ type	is	text
  │ data	matches	'.*[Ff]ile "([^"]+)", line ([0-9]+), characters ([0-9]+)-([0-9]+).*'$nl'?'
  │ arg	isfile	$1
  │ data	set	$file
  │ attr	add	addr=$2-#0+#$3,$2-#0+#$4
  │ plumb	to	edit
  │ plumb	client	$editor
  │ 
  │ # example: File "tests/dune", line 2, characters 7-22:
  │ type	is	text
  │ data	matches	'.*[Ff]ile "([^"]+)", lines ([0-9]+)-([0-9]+).*'$nl'?'
  │ arg	isfile	$1
  │ data	set	$file
  │ attr	add	addr=$2,$3
  │ plumb	to	edit
  │ plumb	client	$editor
  └────

  It could probably be extended to search `~/.opam' so you could plumb
  errors in files outside of your project, but I do not use opam, so I
  haven’t needed to do it.

  Here is a short demo of its use: <https://youtu.be/Evl-N0oNNd0>

  It’s not in OCaml, but I also wrote
  <https://github.com/droyo/acme-autoformat> and put an `OcamlFmt'
  script in acme’s $PATH like so:

  ┌────
  │ #!/bin/sh
  │ exec /usr/local/bin/acme-autoformat -r '\.mli?$' \
  │ 	-- ocamlformat --name='{{.Basename}}' --enable-outside-detected-project -
  └────

  This calls `ocamlformat' whenever I Put an .ml[i] file. This is
  probably obviated by combining acme-lsp and ocaml-lsp, but these two
  bits work well enough that I haven’t felt a need to pursue it.


[Acme] <https://acme.cat-v.org/>


Other OCaml News
════════════════

>From the ocaml.org blog
───────────────────────

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

  • [Tarides Sponsors Girls Can Code]
  • [Introducing the Jane Street Graduate Research Fellowship]


[the ocaml.org blog] <https://ocaml.org/blog/>

[Tarides Sponsors Girls Can Code]
<https://tarides.com/blog/2022-09-06-tarides-sponsors-girls-can-code>

[Introducing the Jane Street Graduate Research Fellowship]
<https://blog.janestreet.com/graduate-research-fellowship/>


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 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] <mailto:alan.schmitt@polytechnique.org>

[the archive] <https://alan.petitepomme.net/cwn/>

[RSS feed of the archives] <https://alan.petitepomme.net/cwn/cwn.rss>

[online] <http://lists.idyll.org/listinfo/caml-news-weekly/>

[Alan Schmitt] <https://alan.petitepomme.net/>


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