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OCaml Planet

The OCaml Planet aggregates various blogs from the OCaml community. If you would like to be added, read the Planet syndication HOWTO.

987 blog posts are available. You can read the 30 more recent ones below or view older ones.

ocaml-git 2.0 — Tarides (Romain C.), Oct 19, 2018

I'm very happy to announce a new major release of ocaml-git (2.0). This release is a 2-year effort to get a revamped streaming API offering a full control over memory allocation. This new version also adds production-ready implementations of the wire protocol: git push and git pull now work very reliably using the raw Git and smart HTTP protocol (SSH support will come soon). git gc is also implemented, and all of the basic bricks are now available to create Git servers. MirageOS support is a…


OCamlPro’s TZScan grant proposal accepted by the Tezos Foundation – joint press release — OCamlPro, Oct 17, 2018

Tezos Foundation and OCamlPro joint press release – October 17, 2018

We are pleased to announce  that the Tezos Foundation has issued a grant to OCamlPro to support its work on TzScan, a block explorer for the Tezos blockchain that will be made open-source.

OCamlPro is a French company and R&D lab, focused on OCaml and blockchain development. OCamlPro, which is an active community member and contributor to Tezos, has initiated several Tezos-related projects such as TzScan and Liquidit…


OCamlFormat 0.8 — Tarides (Guillaume P.), Oct 17, 2018

We are proud to announce the release of OCamlFormat 0.8 (available on opam). To ease the transition from the previous 0.7 release here are some highlights of the new features of this release. The full changelog is available on the project repository.

Precedence of options

In the previous version you could override command line options with .ocamlformat files configuration. 0.8 fixed this so that the OCamlFormat configuration is first established by reading .ocamlformat and .ocp-indent files:


Full Time: Software Developer (Functional Programming) at Jane Street in New York, NY; London, UK; Hong Kong — GitHub Jobs, Oct 01, 2018

Software Developer

Jane Street is a proprietary quantitative trading firm, focusing primarily on trading equities and equity derivatives. We use innovative technology, a scientific approach, and a deep understanding of markets to stay successful in our highly competitive field. We operate around the clock and around the globe, employing over 500 people in offices in New York, London and Hong Kong.

The markets in which we trade change rapidly, but our intellectual approach changes faster still…


Full Time: Compiler Engineer at Jane Street in New York & London — GitHub Jobs, Oct 01, 2018

Jane Street is a proprietary quantitative trading firm, focusing primarily on trading equities and equity derivatives. We use innovative technology, a scientific approach, and a deep understanding of markets to stay successful in our highly competitive field. We operate around the clock and around the globe, employing over 500 people in offices in New York, London and Hong Kong.

The markets in which we trade change rapidly, but our intellectual approach changes faster still. Every day, we have …


OCaml Workshop 2018 — Tarides (Romain C.), Sep 27, 2018

The OCaml Users and Developers Workshop brings together industrial users of OCaml with academics and hackers who are working on extending the language, type system and tools. OCaml 2018 was held on September 27th, 2018 in St. Louis, Missouri, USA, colocated with ICFP 2018.

Check Tarides' talks: RFCs, all the way down! and The OCaml Platform 1.0.

Coq 8.8.2 is out — Coq, Sep 26, 2018

The 8.8.2 release of Coq is available.

Main changes:

  • The kernel does not tolerate capture of global universes by polymorphic universe binders, fixing a soundness break (triggered only through custom plugins)
  • A PDF version of the reference manual is available once again.
  • The coq-makefile targets print-pretty-timed, print-pretty-timed-diff, and print-pretty-single-time-diff now correctly label the "before" and "after" columns, rather than swapping them.
  • The Windows installer now includes many mo…

opam 2.0.0 release and repository upgrade — OCamlPro, Sep 19, 2018

We are happy to announce the final release of opam 2.0.0.

A few weeks ago, we released a last release candidate to be later promoted to 2.0.0, synchronised with the opam package repository upgrade.

You are encouraged to update as soon as you see fit, to continue to get package updates: opam 2.0.0 supports the older formats, and 1.2.2 will no longer get regular updates. See the Upgrade Guide for details about the new features and changes.

The website opam.ocaml.org has been updated, with the full…


Continuous Benchmarking & Call for Benchmarks — KC Sivaramakrishnan, Sep 13, 2018

Over the past few weeks, at OCaml Labs, we’ve deployed continuous benchmarking infrastructure for Multicore OCaml. Live results are available at http://ocamllabs.io/multicore. Continuous benchmarking has already enabled us to make informed decisions about the impact of our changes, and should come in handy over the next few months where we polish off and tune the multicore runtime.

Currently, the benchmarks are all single-threaded and run on x86-64. Our current aim is to quantify the perfor…


Dune 1.2.0 — Tarides (Etienne M.), Sep 06, 2018

After a tiny but important patch release as 1.1.1, the dune team is thrilled to announce the release of dune 1.2.0! Here are some highlights of the new features in that version. The full list of changes can be found in the dune repository.

Watch mode

When developing, it is common to edit a file, run a build, read the error message, and fix the error. Since this is a very tight loop and developers are doing this hundreds or thousands times a day, it is crucial to have the quickest feedback possi…


How to implement type theory in an hour — Andrej Bauer, Aug 25, 2018

I was purging the disk on my laptop of large files and found a video lecture which I forgot to publish. Here it is with some delay. I lectured on how to implement type theory at the School and Workshop on Univalent Mathematics in December 2017, at the University of Birmingham (UK).

You may watch the video and visit the accompanying GitHub repository spartan-type-theory.

Ann: A new ppx for tyre and new version of ppx_regexp | Drup's thingies — Gabriel Radanne, Aug 21, 2018

Some times ago, I released Tyre, a library for Typed Regular Expressions that allows matching, printing and routing. While many people expressed interest, the syntax was (rightfully) considered too obtuse for practical usage. Thanks to Petter A. ‘paurkedal’ Urkedal, this should now be fixed!

Not-learning is a skill too — Gaius Hammond, Jul 29, 2018

To be successful in tech, it’s well known that you must keep your skills up to date. The onus is on each individual to do this, no-one will do it for you, and companies that provide ongoing personal development are few and far between. Many companies would rather “remix our skills”, which means laying off workers with one skill (on statutory minimum terms) and hiring people with the new skill. Which is short-termist in the extreme; the new workers are no better than the old, th…


opam 2.0.0 RC4-final is out! — OCamlPro, Jul 26, 2018

We are happy to announce the opam 2.0.0 final release candidate! 🍾

This release features a few bugfixes over Release Candidate 3. It will be promoted to 2.0.0 proper within a few weeks, when the official repository format switches from 1.2.0 to 2.0.0. After that date, updates to the 1.2.0 repository may become limited, as new features are getting used in packages.

It is safe to update as soon as you see fit, since opam 2.0.0 supports the older formats. See the Upgrade Guide for details about the …


frama-clang 0.0.6, compatible with Frama-C 17 Chlorine is out. Download ithere. — Frama-C, Jul 23, 2018

Algebraic effects and handlers at OPLSS 2018 — Andrej Bauer, Jul 22, 2018

I have had the honor to lecture at the Oregon Programming Language Summer School 2018 on the topic of algebraic effects and handlers. The notes, materials and the lectures are available online:

I gave four lectures which started with the mathematics of algebraic theories, explained how they can be used to model computational effects, how we make a programming langu…


OCamlPro’s Tezos block explorer TzScan’s last updates — OCamlPro, Jul 20, 2018

OCamlPro is pleased to announce the latest update of TZScan (http://tzscan.io), its Tezos block explorer to ease the use of the Tezos network. TzScan is now ready for the protocol update scheduled for tomorrow. In addition to some minor bugfixes, the main novelties are:


Station F — Tarides (Thomas G.), Jul 17, 2018

We are thrilled to have been accepted into the Founders Progam's 3rd batch at Station F! Station F is "the only startup campus gathering a whole entrepreneurial ecosystem under one roof" and is providing 3000+ desks and 26 international startup programs. Our Paris offices are now located in that incredible place, close to "métro Chevaleret" (Paris 13).

If you are in Paris, drop us an email to visit our beautiful campus!

OCaml 4.07.0 released — Caml INRIA, Jul 10, 2018

Coq 8.8.1 is out — Coq, Jul 09, 2018

The 8.8.1 release of Coq is available.

It includes four critical bug fixes, many other bug fixes, documentation improvements and user message improvements.

For details, see CHANGES and the 8.8.1 milestone. Feedback and bug reports are extremely welcome.

Bucket Sort — Shayne Fletcher, Jun 10, 2018

Bucket Sort

Bucket sort assumes input generated by a random process that distributes elements uniformly over the interval [0, 1).

The idea of bucket sort is to divide [0, 1) into n equal-sized subintervals or buckets, and then distribute the n input numbers into the buckets. To produce the output, sort the numbers in each bucket and then go through the buckets in order. Sorting a bucket can be done with insertion sort.

let rec insert x = function
| [] -> [x]
| h :: tl as ls ->
if x <…

Frama-C 17 - Chlorine is out. Download ithere. — Frama-C, May 31, 2018

An OCaml quine | Drup's thingies — Gabriel Radanne, May 30, 2018

(fun x -> Printf.printf "%s %S" x x) "(fun x -> Printf.printf \"%s %S\" x x)"

OCaml Users in Paris (OUPS) — Tarides (Thomas G.), May 23, 2018

Thomas Gazagnaire gave a presentation on MirageOS to the OCaml meetup in Paris.

Check the slides for more details.

MirageOS + Tezos funding — Tarides (Thomas G.), May 23, 2018

We are excited to announce that the Tezos Foundation will trust Tarides to package Tezos nodes as MirageOS unikernel, which will help participants establish nodes on the Tezos network in a more efficient and secure manner.

See the press release for more details.

opam 2.0.0 Release Candidate 2 is out! — OCamlPro, May 22, 2018

We are pleased to announce the release of a second release candidate for OPAM 2.0.0.

This new version brings us very close to a final 2.0.0 release, and in addition to many fixes, features big performance enhancements over the RC1.

Among the new features, we have squeezed in full sandboxing of package commands for both Linux and Mac OS, to protect our users from any misbehaving scripts.

NOTE: if upgrading manually from 2.0.0~rc, you need to run opam init --reinit -ni to enable sandboxing.

The ne…


simpl is less annoying than you think — GaGallium (Nathanaël Courant, Armaël Guéneau), May 22, 2018

In this blogpost we find out that it is possible to tweak the behavior of the Coq simpl tactic. We find it particularly useful when dealing with arithmetic goals on Z.

We just discovered an answer to a longstanding annoyance we faced when dealing with arithmetic Coq goals. Consider the following Coq goal, using integers on Z:

Require Import ZArith.
Open Scope Z_scope.

Goal forall a, 2 * a = 0 * a + a * 2.
  intros. simpl.

We call the simpl tactic to simplify 0 * a + ... into .... Unfort…


Dijkstra's algorithm — Shayne Fletcher, May 20, 2018

Shortest Path

This article assumes familiarity with Dijkstra's shortest path algorithm. For a refresher, see [1]. The code assumes open Core is in effect and is online here.

The first part of the program organizes our thoughts about what we are setting out to compute. The signature summarizes the notion (for our purposes) of a graph definition in modular form. A module implementing this signature defines a type vertex_t for vertices, a type t for graphs and type extern_t


Irmin usability enhancements — Tarides (Zach S.), May 18, 2018

Zach Shipko is working on improving the UI/UX for Irmin. He is looking for feedback to make Irmin more accessible to potential users and clean up the rough edges for existing users.

Invited lecture at ENS — Tarides (Thomas G.), May 17, 2018

Thomas Gazagnaire gave an invited lecture at the computer science department of ENS, in Paris. This was part of the system and network L3 course.

Check the slides (in english) and the exercices (in french).

View older blog posts.