OCaml Weekly News
Hello
Here is the latest OCaml Weekly News, for the week of April 28 to May 05, 2020.
Table of Contents
- Lwt now has let* syntax
- JOSE 0.3.0 - Now with 100% more encryption
- Are there learning materials for OCaml for those with no programming experience?
- The recent evolution of utop, lambda-term, zed and underneath projects
- Looking for "lovely, idiomatic" examples of Ocaml used for shell-scripting in the manner of Perl/Python (but esp. Perl)
- Old CWN
Lwt now has let* syntax
Anton Bachin announced
Lwt now has let*
and let+
syntax, which can be used like this:
open Lwt.Syntax let () = let request = let* addresses = Lwt_unix.getaddrinfo "google.com" "80" [] in let google = Lwt_unix.((List.hd addresses).ai_addr) in Lwt_io.(with_connection google (fun (incoming, outgoing) -> let* () = write outgoing "GET / HTTP/1.1\r\n" in let* () = write outgoing "Connection: close\r\n\r\n" in let* response = read incoming in Lwt.return (Some response))) in let timeout = let* () = Lwt_unix.sleep 5. in Lwt.return None in match Lwt_main.run (Lwt.pick [request; timeout]) with | Some response -> print_string response | None -> prerr_endline "Request timed out"; exit 1
This is now released in Lwt 5.3.0. Thanks to Rahul Kumar for
adding let*
, and @CraigFe for adding let+
!
Thomas Coopman asked
Awesome this looks great.
2 quick questions:
- I don't see this new version documented on ocsigen yet? Is that a build that needs to be done manually?
- Is
ppx_lwt
still recommend for some usecases liketry%
? For what cases is one preferred over the other?
Anton Bachin replied
Good questions :slight_smile:
- The docs generation is blocked on an Ocsigen "internal" package
wikidoc
, which has not been updated to support 4.08. So, effectively,let*
is exactly what is preventing docs generation for the time being. I'll post the docs as soon as that is fixed. ppx_lwt
is probably still the recommended way, because of better backtraces, and things liketry%lwt
.let*
is nice for people that don't want to use the PPX. They can still benefit from a monadic syntax.
JOSE 0.3.0 - Now with 100% more encryption
Ulrik Strid announced
I recently released a version 0.3.0 of JOSE.
https://github.com/ulrikstrid/reason-jose
https://ulrikstrid.github.io/reason-jose
It now includes some of the JWE (JSON Web Encryption) spec. A huge thank you goes out to @hannes for helping me
implementing one of the gnarlier combinations of decryption that I could then use as a base for encryption and more
alg
and enc
.
I also refactored the JWK (JSON Web Keys) implementation to unify and simplify the representation. It is now possible to use a private key for anything a public key can do since it's a superset.
A special thanks to @anmonteiro for helping me with the design and reviewing my code.
Are there learning materials for OCaml for those with no programming experience?
Aaron Christianson asked
OCaml is a language with some advanced features, but a very gentle learning curve. It seems like it would be well-suited to teaching beginners to program (a few tricky error messages notwithstanding), but I haven't seen many resources targeted at teaching programming from scratch. Does anyone here know any?
Daniel Bünzli replied
There is OCaml from the Very Beginning written by @JohnWhitington.
Nicolás Ojeda Bär also replied
An excellent (free) book is "LE LANGAGE CAML" https://caml.inria.fr/pub/distrib/books/llc.pdf.
Pierre also replied
There's also CS3110 from Cornell University. Here's the textbook. It's pretty great!
The recent evolution of utop, lambda-term, zed and underneath projects
ZAN DoYe announced
Hi, dear OCaml guys! We've been keeping quiet for more than one year though utop, lambda-term, zed and some related projects were still evolving during the period of time. This is because of two reasons:
The new feature had nothing to do with the fields where most OCaml developers are working on:
Recognizing, editing, fuzzy searching for Character Variation(mainly for ancient CJK characters).
Nevertheless, the new feature brought us a good side effect – the long-existing Issue with asian charset was resolved. UTop users will notice the refinement naturally, so no announcement was needed.
- I didn't deem the first few new editions of zed 2 and lambda-term 2 stable enough.
3.0 era
This time, we are entering zed 3, lambda-term 3 era. The features introduced since zed 2, lambda-term 2 are quite stable now and the new feature coming to us will have a bit more impact, especially to vim users. So it's worthwhile to draft an announcement:
List of notable changes:
- zed 2:
- wide, combined glyph(Character Variation, IPA, CJK …)
- add wanted_column support for wide width character
- lambda-term 2:
- wide, combined glyph(Character Variation, IPA, CJK …)
- add horizontal scrolling support for wide width character
- zed 3:
- add new actions for convenience
- lambda-term 3:
LTerm_read_line
: add initial support for vi editing mode:- motions:
- h l 0 ^ $
- j k gg G
- w W e E b B ge gE
- f F t T
- aw iw aW iW
- include or inner ( ), [ ], { }, < >, ' and "
- generic quote: aq? iq? where ? could be any character
- bracket matching: jump back and forth between matched brackets
- delete, change, yank with motions
- paste: p P
- line joining: J
for a full list of the changes, please visit the homepages of each project.
Projects underneath:
- charInfo_width: Determine column width for a character
- mew & mew_vi: Modal editing witch & Its VI interpreter complement. In a word, modal editing engine generators.
What's next
- VI Editing Mode
Visual mode
- register support and more vi compatible
- CJKV
We've recorded more then 100 thousand entries about the structure of CJK characters, what is a character consists of, how are the sub-assemblies glue together etc. And as a complement to charInfo_width, we may release a new project called charInfo_structure ;)
Looking for "lovely, idiomatic" examples of Ocaml used for shell-scripting in the manner of Perl/Python (but esp. Perl)
Chet Murthy announced
I wonder if there are people who have written nontrivial Ocaml code for shell-scripting, that they think exemplifies the right way to do it. I've been a Perl hacker for 25yr, and so when I reach for Ocaml to write stuff that should be Perl shell-scripts, I always find it a bit painful, and there's a significant overhead to getting the job done. Some of that is applying ocaml to a new domain, but some of it is that I'm just not using the right idioms and tools (and there are so many to choose from).
So if anybody has good pointers, I'd appreciate learning about them.
Bikal Lem
Haven't tried it myself, but this looks promising … https://github.com/janestreet/shexp.
At least it has the great Sean Connery in its README so possibly worth delving a bit. :)
Hezekiah Carty
bos seems like it can do a lot of what you're looking for. It's at least worth taking a look, though it may not be at Perl levels of concise for this kind of task.
Martin Jambon
I tried to summarize my take on the subject into this gist: https://gist.github.com/mjambon/bb07b24f89fa60c973735307ce9c6cb9
I'm not aware of the existence of such tool, but this is how I might design it. This should be reminiscent of camlp4's quotation and anti-quotation system, which allows alternating between two syntaxes within a source file.
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.