OCaml Weekly News

Hello

Here is the latest OCaml Weekly News, for the week of August 27 to Septembe= r 03, 2024.

ppx_minidebug 2.0: verbosity levels

Archive: https://discuss.ocaml.org/t/ann-ppx-minidebug-2-0-verb= osity-levels/15212/1

Lukasz Stafiniak announced

I'm pleased to mention that ppx_minidebug 2.0 is available now. The README at ppx_minidebug - GitHub is the u= ser manual, and the runtime API is documented here: pp= x_minidebug.Minidebug_runtime.

Version 2.0 brings linear verbosity log levels. Both logging scopes and ind= ividual log statements can be either: at a default (omitted) log level, at = a compile-time log level (e.g. [%log2 "test"] logs test<= /code> at level 2), or at a runtime-provided log level (e.g. [%logN f= or_level; "test"] logs test at level for_level). When the level to log at is omitted, it is inherited from its direct= syntactic logging scope (i.e. the log entry that the log or log entry is s= yntactically in – not the log entry that the log is dynamically atta= ched to, if it's different). Providing a compile-time log level will prune = the generated code accordingly. See more here: ppx_minidebug: Using as a logging framework.




Version 1.6 brought support for local runtimes, where the runtime for loggi=
ng in a logging scope is fetched by a user-provided function. The function =
can for example use domain-local storage. See more here: ppx_minidebug: Dealing with concurrent execution.



Happy debugging!







Ppx by example - repo to help on ppx learning


Archive: https://discuss.ocaml.org/t/ppx-by-example-repo-t=
o-help-on-ppx-learning/15213/1




Pedro Braga announced


Over the past few weeks, I've started my journey to learn PPX, and during t=
his process, I found it challenging to find examples. So, I began creating =
my own examples and adding explanations for myself.



I realized that I could make my examples and explanations public because th=
is would push me to learn more deeply (as I=E2=80=99d need to provide bette=
r and clearer explanations) and could also help anyone else on this learnin=
g path. @davesnx also encouraged me to share my process (maybe through a bl=
og post in the future). So, I created this repository: github.com/pedrobslisboa/ppx-by-exa=
mple.



The idea is to have examples and an explanation for each detail on those. I=
t has also a brief explanation about the subject on every README.



I have a few notes:


It is a wip project, which means that there are parts in development. B=
ut sharing it is also a way to push me to improve this project.
As I said, I'm on the process of learning PPX, so probably I missed or =
added something wrongly, so please If you notice it, share it on the repo s=
o I can fix.
I am also in the process of learning OCaml. I started coding in OCaml t=
his year (professionally just last month), so this repository might not hav=
e the best code. If you think it can be improved, please let me know. :hear=
t:
I'm not a native English speaker or the best writer. I asked ChatGPT to=
 help fix some mistakes and improve cohesion, but if you notice anything th=
at needs to be improved, please let me know. :heart:



Besides that, any comments, help, or additions are welcome. I hope this can=
 be helpful :3
Thank you all!









Blog Post: Simple Example where Ocaml calls a C function


Archive: https://discuss.ocaml.org/t/blog-post=
-simple-example-where-ocaml-calls-a-c-function/15211/3




Deep in this thread, Tim McGilchrist said


My favourite example at the moment is this one from Retrofitting Effect Handlers onto OCaml. I=
t shows OCaml calling C, C calling an OCaml callback and exceptions crossin=
g those boundaries.


$ cat meander.ml



external ocaml_to_c
         : unit -> int =3D "ocaml_to_c"<=
/span>
exception E1
exception E2
let c_to_ocaml () =3D raise E1
let _ =3D Callback.=
register
          "c_to_ocaml" c_to_ocaml
let omain () =3D
  try (* h1 *)
    try (* h2 *) ocaml_to_c ()
    with E2 -> 0
  with E1 -> 42
let _ =3D assert (omain () =3D 42)



$ cat meander_c.c



#include <caml/mlvalues.h>
#include <caml/callback.h>

value value unit) {
    caml_callback(*caml_named_value
                  ("c_to_ocaml"), Va=
l_unit);
    return Val_in=
t(0);
}




Compile it with OCaml 5.2:


$ ocamlopt --version
5.2.0
$ ocamlopt meander_c.c meander.ml -o meander.exe
$ ./meander.exe
$ echo $?
0



Bonus you can use GDB/LLDB on this to set breakpoints in both OCaml and C.









Outreachy December 2024 Round


Archive: https://discuss.ocaml.org/t/outreachy-december-2024-round/15223=
/1




Patrick Ferris announced


With the conclusion of the previous Outreachy round (see Outreachy Demo Pres=
entation), the next round is fast approaching and the OCaml community h=
as signed up again to participate!




The Next Round


The deadline for mentors to submit a project is [date=3D2024-09-11 timezone=3D"Eur=
ope/London"]. If people are interested in mentoring and they maintain a=
n open-source project, then they can reach out directly to me and I can hel=
p scope a project, explain the contribution period and provide as much othe=
r help as we can! Co-mentoring is also an option for people who are interes=
ted in mentoring but do not have a specific project – do reply to th=
is thread if that's you!=20



When signing up mentors propose an open-source project where prospective in=
terns submit PRs during the =E2=80=9Ccontribution phases=E2=80=9D as part o=
f their application. Mentors will then choose an intern to work with for 3 =
months. A more detailed explanation is available on the Outreachy mentor section .



I'm particularly interested in projects from some of the larger OCaml pr=
ojects (e.g. dune, opam, ppxlib, miou, eio, cohttp, melange etc.). I'm =
very happy to help with co-mentoring on any of these projects. If you are i=
nterested and are a maintainer of a larger project, please do reach out. Of=
 course, smaller projects are still very much possible.=20





Funding


Funding for this upcoming Outreachy round is not =
yet finalised. We hope to have funding for three interns, I will rep=
ly to this thread once things are confirmed which should be soon. If any co=
mpany is interested in supporting the OCaml community Outreachy initative p=
lease do reach out to me.



I'd also like to take this moment to raise some awareness for the current <=
a href=3D"https://www.outreachy.org/blog/2024-08-14/outreachy-needs-your-he=
lp/">struggles Outreachy is facing. The OCaml community has benefited m=
assively from Outreachy. Both by participating directly as a community (see=
 https://ocaml.org/outreachy fo=
r some past projects) and via the participation of other communities. I'm v=
ery grateful for everyone who has taken part in some way, including non-men=
tors engaging with the interns.=20



As always if you have any general questions or mentoring ideas do comment o=
n this thread or reach out directly.



Thanks!










Other OCaml News



From the ocaml.org blog


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



The Biggest=
 Functional Programming Conference of the Year: What are we Bringing to ICF=
P?
ICFP 2024<=
/li>
Project-Wide Occurrences: A =
New Navigation Feature for OCaml 5.2 Users
What the interns have wrought, 2024 edition









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

ppx_minidebug 2.0: verbosity levels

Lukasz Stafiniak announced

Ppx by example - repo to help on ppx learning

Pedro Braga announced

Blog Post: Simple Example where Ocaml calls a C function

Deep in this thread, Tim McGilchrist said

Outreachy December 2024 Round

Patrick Ferris announced

The Next Round

Funding

Other OCaml News

From the ocaml.org blog

Old CWN