We're happy to announce the release of opam-publish 2.5.0!

We're happy to announce the release of Odoc 2.4.4 which brings compatibility with OCaml 5.3!

After almost a year of work, OCamlformat 0.27.0 is finally available with support for 5.3 syntax!

This release includes the new function syntax from OCaml 5.2, the effect keyword from OCaml 5.3 and a large number of bug fixes and improvements.

An other notable change, is that comments are now formatted by default.

One month after the release of the first beta for OCaml 5.3.0, we are releasing a second and hopefully last beta release for OCaml 5.3.0 .

The most notable changes for this second beta are probably a handful of type system bugfixes. In particular, those fixes revert a change of behaviour in the first beta when pattern matching GADTs with non-injective type parameters.

We also have a C++ header compatibility fix and the restoration of some configuration variable in Makefiles for the sake of backward compatibility.

Overall, the release is converging and we are expecting to have a first release candidate around the middle of December. The progresses on stabilising the ecosystem are tracked on the opam readiness for 5.3.0 meta-issue.

Meanwhile, the second beta release of OCaml 5.3.0 is here to help you update your software and libraries ahead of the release (see below for the installation instructions).

The full release is expected before the end of December.

If you find any bugs, please report them on OCaml's issue tracker.

If you are interested in full list of features and bug fixes of the new OCaml version, the updated change log for OCaml 5.3.0 is available on GitHub.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.3.0~beta2

The source code for the beta is also available at these addresses:

• GitHub
• OCaml archives at Inria

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.3.0~beta2+options <option_list>

where option_list is a space separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.3.0~beta2+flambda+nffa ocaml-variants.5.3.0~beta2+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

We're happy to announce the release of Dune 3.17.0.

Among the list of chances, this release enables the Dune cache by default for known-safe operations, adds support for Wasm_of_ocaml, adds support for the -H compiler flag introduced in OCaml 5.2 and allows specifying code hosting services like Codeberg or Gitlab organizations.

We have the pleasure of announcing the release of OCaml 5.2.1, dedicated to the memory of Niels Bohr and Paul Éluard on the anniversary of their deaths.

OCaml 5.2.1 is a collection of safe but import runtime time bug fixes backported from the 5.3 branch of OCaml.

The full list of changes is available above for more details.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands:

opam update
opam switch create 5.2.1

The source code for the release is also directly available on:

• GitHub
• Inria archive

Discuss this post on Discuss!

Dune can install and run developer tools in the context of a project. This feature is available in the Dune Developer Preview and in the upcoming release of Dune 3.17. As with all of Dune's package management features, consider this feature to be unstable as its UI and semantics may change without notice.

The currently supported tools are ocamllsp and ocamlformat. Dune has a new command dune tools exec <TOOL> -- [ARGS]... which downloads and installs the given tool, and then runs it with the given arguments (note the -- which separates arguments to dune from arguments to the tool). Tools are installed locally to the project, in its _build directory, which makes it easy to use different versions of a tool in different projects. An unfortunate consequence of installing tools into _build is that for the time being all tools are uninstalled whenever dune clean is run.

Let's see it in action:

$ dune tools exec ocamlformat -- --version
Solution for dev-tools.locks/ocamlformat:
- ocamlformat.0.26.2+binary-ocaml-5.2.0-built-2024-11-07.0-x86_64-unknown-linux-musl
    Building ocamlformat.0.26.2+binary-ocaml-5.2.0-built-2024-11-07.0-x86_64-unknown-linux-musl
     Running 'ocamlformat --version'
0.26.2

Precompiled Binaries

Note that in the example above, Dune's package solver chose to install version 0.26.2+binary-ocaml-5.2.0-built-2024-11-07.0-x86_64-unknown-linux-musl of ocamlformat. This packages comes from a new repository of binary packages containing pre-built executables for a select few Opam packages. Dune will search this repository in addition to the default repositories when solving packages for tools only (if a project has ocamlformat in its dependencies, the binary repository won't be searched while solving the project's dependencies).

The goal of the binary repository is to reduce the time it takes to get started working on a new project. Without it, Dune would need to build ocamlformat from source along with all of its dependencies, which can take several minutes.

For now only a small number of package versions are contained in the binary repository. To demonstrate, here's what happens if we run dune tools exec ocamlformat in a project with version=0.26.1 in its .ocamlformat file:

 $ dune tools exec ocamlformat -- --version
Solution for dev-tools.locks/ocamlformat:
- astring.0.8.5
- base.v0.17.1
- base-bytes.base
- base-unix.base
- camlp-streams.5.0.1
- cmdliner.1.3.0
...
- ocamlformat.0.26.1
...
    Building base-unix.base
    Building ocaml-base-compiler.5.1.1
    Building ocaml-config.3
    Building ocaml.5.1.1
    Building seq.base
    Building cmdliner.1.3.0
...
    Building ocamlformat.0.26.1
     Running 'ocamlformat --version'
0.26.1

Dune parses .ocamlformat to determine which version of ocamlformat to install, and 0.26.1 is not in the binary repo so it needed to be built from source.

If your project requires a version of a package not available in the binary repository, or you're on an operating system or architecture for which no binary version of a package exists, the package will be built from source instead. Currently the binary repository contains binaries of ocamlformat.0.26.2, ocaml-lsp-server.1.18.0 and ocaml-lsp-server.1.19.0 for x86_64-unknown-linux-musl, x86_64-apple-darwin and aarch64-apple-darwin.

Note that Linux binaries are statically linked with muslc so they should work on all distros regardless of dynamic linker.

Running ocamllsp

The program ocamllsp from the package ocaml-lsp-server analyzes OCaml code and sends information to text editors using the Language Server Protocol. The tool is crucial to OCaml's editor integration and it has a couple of quirks that are worth mentioning here.

TL;DR: Install Dune with the install script on the Developer Preview page and you'll get an ocamllsp shell script that will install and run the correct version of ocamllsp for your project.

Firstly the ocamllsp executable can only analyze code that has been compiled with the same version of the OCaml compiler as was used to compile the ocamllsp executable itself. Different versions of the ocaml-lsp-server package are incompatible with some versions of the OCaml compiler (e.g. ocaml-lsp-server.1.19.0 must be built with at least 5.2.0 of the compiler). This means that when Dune is choosing which version of ocaml-lsp-server to install it needs to know which version of the compiler your project is using. This is only known after the project has been locked (by running dune pkg lock), so Dune will refuse to install ocamllsp in a project that doesn't have a lock directory or for a project that doesn't depend on the OCaml compiler.

$ dune tools exec ocamllsp
Error: Unable to load the lockdir for the default build context.
Hint: Try running 'dune pkg lock'

The ocaml-lsp-server packages in the binary repository contain metadata to ensure that the ocamllsp executable that gets installed was built with the same version of the compiler as your project. For example the ocaml-lsp-server package built with ocaml.5.2.0 contains this line:

conflicts: "ocaml" {!= "5.2.0"}

This prevents it from being chosen if the project depends on any version of the compiler other than 5.2.0.

Another quirk is that ocamllsp will try to invoke the binaries ocamlformat and ocamlformat-rpc, both found in the ocamlformat package. The ocaml-lsp-server package doesn't depend on ocamlformat as the specific version of ocamlformat needed by a project is implied by the project's .ocamlformat file, which package managers don't consider when solving dependencies. This means that in general (whether using Dune or Opam for package management) it's up to the user to make sure that the correct version of ocamlformat is installed in order to use the formatting features of ocamllsp.

Otherwise expect this error in your editor:

Unable to find 'ocamlformat-rpc' binary. Types on hover may not be well-formatted. You need to install either 'ocamlformat' of version > 0.21.0 or, otherwise, 'ocamlformat-rpc' package.

Even if ocamllsp and ocamlformat are both installed by Dune, if you run dune tools exec ocamllsp you will find that ocamllsp still can't find the ocamlformat or ocamlformat-rpc executables. This is because unlike Opam, Dune does not install tools into your $PATH, and for the sake of simplicity, the dune tools exec <TOOL> command does not modify the environment of the tool it launches. This can be fixed by adding _build/_private/default/.dev-tool/ocamlformat/ocamlformat/target/bin (the directory containing ocamlformat and ocamlformat-rpc when ocamlformat is installed by dune) to the start of your $PATH variable before running dune tools exec ocamllsp. For example starting ocamllsp with the following shell script:

OCAMLFORMAT_TARGET="_build/_private/default/.dev-tool/ocamlformat/ocamlformat/target"

if [ ! -f $OCAMLFORMAT_TARGET/cookie ]; then
    # Make sure that the ocamlformat dev tool is installed as it's needed by
    # ocamllsp. There's currently no command that just installs ocamlformat so
    # we need to run it and ignore the result.
    dune tools exec ocamlformat -- --help > /dev/null
fi

# Add ocamlformat to the environment in which ocamllsp runs so ocamllsp can invoke ocamlformat.
export PATH="$PWD/$OCAMLFORMAT_TARGET/bin:$PATH"

# Build and run ocamllsp.
dune tools exec ocamllsp -- "$@"

Of course, it's rare to manually start ocamllsp directly from your terminal. It's normally launched by text editors. It would be impractical to configure your text editor to modify $PATH and run a custom command to start ocamllsp via Dune, and doing so would make it impossible to edit any project that doesn't use Dune for package management. Instead, the Dune Developer Preview ships with a shell script which installs ocamlformat and adds its bin directory to $PATH before launching dune tools exec ocamllsp. The script is simply named ocamllsp, and the Dune Developer Preview install script adds it to ~/.dune/bin which should already be in your $PATH if you're using the Developer Preview. The ocamllsp script also attempts to fall back to an Opam-managed installation of ocamllsp if it doesn't detect a Dune lockdir so the same script should work for non-Dune projects. Because the script is named the same as the ocamllsp executable, most editors don't require special configuration to run it. See the "Editor Configuration" section of the Dune Developer Preview page for more information about setting up your editor.

Some parts of the ocamllsp shell script may eventually make their way into Dune itself, but for the time being the shell script is the recommended way to launch ocamllsp for users of the Dune Developer Preview. The net result is that as long as your project has a lockfile, the first time you edit some OCaml code in the project Dune will download and run the appropriate version of ocamllsp.

Feedback on this post is welcomed on Discuss!

As mentioned in our talk at the OCaml Workshop 2024, we decided to switch to a time-based release cycle (every 6 months), starting with opam 2.3.

As promised, we are very pleased to announce the release of opam 2.3.0, and encourage all users to upgrade. Please read on for installation and upgrade instructions.

Try it!

In case you plan a possible rollback, you may want to first backup your ~/.opam or $env:LOCALAPPDATA\opam directory.

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh)"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) }"

or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Major breaking change: extra-files

When loading a repository, opam now ignores files in packages' files/ directories which aren't listed in the extra-files field of the opam file. This was done to simplify the opam specification where we hope the opam file to be the only thing that you have to look at when reading a package specification. It being optional to list all files in the extra-files: field went against that principle. This change also reduces the surface area for potential file corruption as all extra-files must have checksums.

This is a breaking change and means that if you are using the files/ directory without listing them in the extra-files: field, you need to make sure that all files in that directory are included in the extra-files field. The resulting opam file remains compatible with all previous opam 2.x releases.

If you have an opam repository, you should make sure all files are listed so every packages continues to work without any issue, which can be done automatically using the opam admin update-extrafiles command.

Major changes

• Packages requiring an unsupported version of opam are now marked unavailable, instead of causing a repository error. This means an opam repository can now allow smoother upgrade in the future where some packages can require a newer version of opam without having to fork the repository to upgrade every package to that version as was done for the upgrade from opam 1.2 to 2.0

• Add a new opam list --latests-only option to list only the latest versions of packages. Note that this option respects the order options were given on the command line. For example: --available --latests-only will first list all the available packages, then choose only the latest packages in that set; while --latests-only --available will first list all the latest packages, then only show the ones that are available in that set

• Fix and improve opam install --check, which now checks if the whole dependency tree of the package is installed instead of only the root dependencies

• Add a new --verbose-on option to enable verbose output for specified package names. Thanks to @desumn for this contribution

• Add a new opam switch import --deps-only option to install only the dependencies of the root packages listed in the opam switch export file

• opam switch list-available no longer displays compilers flagged with avoid-version/deprecated unless --all is given, meaning that pre-release or unreleased OCaml packages no longer appear to be the latest version

• opam switch create --repositories now correctly infers --kind=git for URLs ending with .git rather than requiring the git+https:// protocol. This is consistant with other commands such as opam repository add. Thanks to @Keryan-dev for this contribution

• opam switch set-invariant now displays the switch invariant using the same syntax as the --formula flag

• The builtin-0install solver was improved and should now be capable of being your default solver instead of builtin-mccs+glpk. It was previously mostly only suited for automated tasks such as Continuous Integration. If you wish to give it a try, simply calling opam option solver=builtin-0install (call opam option solver= restores the default)

• Most of the unhelpful conflict messages were fixed. (#4373)

• Fix an opam 2.1 regression where the initial pin of a local VCS directory would store untracked and ignored files. Those files would usually be cleaned before building the package, however git submodules would not be cleaned and would cause issues when paired with the new behaviour added in 2.3.0~alpha1 which makes opam error when git submodules fail to update (it was previously a warning). (#5809)

• Fix the value of the arch variable when the current OS is 32bit on a 64bit machine (e.g. Raspberry Pi OS). (#5949)

• opam now fails when git submodules fail to update instead of ignoring the error and just showing a warning

• opam's libraries now compile with OCaml >= 5.0 on Windows

• Fix the installed packages internal cache, which was storing the wrong version of the opam file after a build failure. This could be triggered easily for users with custom repositories with non-populated extra-files. (#6213)

• Several improvements to the pre-built release binaries were made:

  • The Linux binaries are now built on Alpine 3.20
  • The FreeBSD binary is now built on FreeBSD 14.1
  • The OpenBSD binary is now built on OpenBSD 7.6 and loses support for OpenBSD 7.5 and earlier
  • Linux/riscv64 and NetBSD/x86_64 binaries are now available

And many other general, performance and UI improvements were made and bugs were fixed. You can take a look to previous blog posts. API changes and a more detailed description of the changes are listed in:

• the release note for 2.3.0~alpha1
• the release note for 2.3.0~beta1
• the release note for 2.3.0~beta2
• the release note for 2.3.0~rc1
• the release note for 2.3.0

This release also includes PRs improving the documentation and improving and extending the tests.

Please report any issues to the bug-tracker.

We hope you will enjoy the new features of opam 2.3!

The release of OCaml version 5.2.1 is imminent.

OCaml 5.2.1 is a collection of safe but import runtime time bug fixes backported from the 5.3 branch of OCaml. The full list of bug fixes is available above.

In order to ensure that the future release works as expected, we are planning to test a release candidate during the upcoming week.

If you find any bugs, please report them here on GitHub.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 5.2.1~rc1

The source code for the release candidate is available on

• GitHub
• Inria archives

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.2.1~rc1+options <option_list>

where <option_list> is a space-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.2.1~rc1+flambda+nffa ocaml-variants.5.2.1~rc1+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

One month and half after the release of the first alpha for OCaml 5.3.0, the release of OCaml 5.3.0 is drawing near.

The internal API of the compiler libraries has been frozen, and most core developer tools support (or will support soon) the new version of the compiler.

We have thus released a first beta version of OCaml 5.3.0 to help you update your software and libraries ahead of the release (see below for the installation instructions). More information about the whole release process is now available in the compiler repository.

Compared to the first alpha release, this beta contains a few runtime or typechecker fixes, a handful of fixes for the runtime event library and other miscellaneous fixes.

Exceptionally, this beta release also introduces a new flag -keywords for the compiler. This backward compatibility flag aims to help compiling old code that are using effect as a normal identifier, now that effect is a keyword in the new effect handler syntax.

The progresses on stabilising the ecosystem are tracked on the opam readiness for 5.3.0 meta-issue.

The full release is expected in the end of November or beginning of December, see the new prospective calendar for more information.

If you find any bugs, please report them on OCaml's issue tracker.

If you are interested in full list of features and bug fixes of the new OCaml version, the updated change log for OCaml 5.3.0 is available on GitHub.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.3.0~beta1

The source code for the beta is also available at these addresses:

• GitHub
• OCaml archives at Inria

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.3.0~beta1+options <option_list>

where option_list is a space separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.3.0~beta1+flambda+nffa ocaml-variants.5.3.0~beta1+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

Feedback on this post is welcomed on Discuss!

We're happy to announce the first and hopefully only release candidate of opam 2.3.0.

This version does not have any significant change compared to the previous 2.3.0~beta2 release and we hope the final release to also have no significant change. Regardless, we invite users to test this version to make sure there isn't any regressions.

Unless a regression is spotted or another problem arises, we hope to have the final release of 2.3.0 out on the 12th of November.

Try it!

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.3.0~rc1"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) } -Version 2.3.0~rc1"

or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Happy hacking!

We're happy to announce the release of Dune 3.16.1.

This is a patch release that fixes an issue with OCaml.5.3.0 and C++ flags.

Discuss this post on Discuss!

Support for dune shell completions for bash and zsh has just landed in the Dune Developer Preview!

Running the installer adds a snippet to your shell config (e.g. ~/.bashrc) that installs a completion handler for dune. The completion script was taken from here, and that page has some information about how the script was generated. Once it's installed the completions will work any time dune is typed at the start of a command, so you can still use the completions when running a version of Dune installed with Opam or your system package manager after installing the Dune Developer Preview.

Currently only command completions are supported. So you can run:

$ dune c<TAB>
cache  clean  coq

...or:

$ dune build -<TAB>
--action-stderr-on-success
--action-stdout-on-success
--always-show-command-line
--auto-promote
--build-dir
--build-info
--cache
...

But if you run dune build <TAB> then it will still suggest local files rather than build targets.

Try it out!

Getting started is easy:

$ curl -fsSL https://get.dune.build/install | sh
$ source ~/.bashrc  # or: source ~/.zshrc
$ dune <TAB>
build
cache
clean
coq
describe
diagnostics
exec
...

Feedback on this post is welcomed on Discuss!

We're happy to announce the second beta release of opam 2.3.0.

As this version is a beta, we invite users to test it to spot previously unnoticed bugs as we head towards the stable release.

Changes

Compared to the previous 2.3.0~beta1 release, the main change is:

• Fix a regression in the detection of the current terminal size that leads to opam output that tries to fit itself into 80 columns regardless of the current terminal size (#6243).

• A NetBSD/x86_64 pre-built release binary is now available

You can view the full list of changes, including API changes, in the release note.

Try it!

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.3.0~beta2"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) } -Version 2.3.0~beta2"

or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Happy hacking!

Feedback on this post is welcome on Discuss!

We're happy to announce the first beta release of opam 2.3.0. Compared to the previous 2.3.0~alpha1 release, you can view the full list of changes in the release note.

This version is a beta, so we invite users to test it to spot previously unnoticed bugs as we head towards the stable release.

Changes

• Fix an opam 2.1 regression where the initial pin of a local VCS directory would store untracked and ignored files. Those files would usually be cleaned before building the package; however, Git submodules would not be cleaned and would cause issues when paired with the new behaviour added in 2.3.0~alpha1, which makes an opam error when Git submodules fail to update (it was previously a warning). (#5809)

• Fix a regression which would make opam crash on platforms where getconf LONG_BIT is not available (e.g., OpenBSD). (#6215)

• Fix the installed packages internal cache, which was storing the wrong version of the opam file after a build failure. This could be triggered easily for users with custom repositories with non-populated extra-files. (#6213)

• Fix a regression in lint W59 with local URLs that are not archives. (#6218)

• Fix the compilation of opam on Windows with OCaml >= 5.0 (again)

• Several improvements to the prebuilt release binaries were made:

  • The Linux binaries are now built on Alpine 3.20
  • The FreeBSD binary is now built on FreeBSD 14.1
  • The OpenBSD binary is now built on OpenBSD 7.6 and loses support for OpenBSD 7.5 and older
  • A Linux/riscv64 binary is now available

API changes are denoted in the release note linked above. This release also includes a couple of PRs improving and extending the tests.

Try It!

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.3.0~beta1"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) } -Version 2.3.0~beta1"

or download manually from the GitHub "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Happy hacking!

Tarides' OCaml Infrastructure team has been hard at work over the last few months, focusing on improving the stability, reliability, and user experience of the OCaml ecosystem's core infrastructure. We are preparing for more substantive changes to come. We will have more fruit from this work to share soon, but updates on our efforts are overdue and we wanted to get you all caught up.

Platform Support

We've expanded and updated our platform support to keep pace with the evolving OCaml ecosystem:

• As part of the compiler release readiness, we've added support for OCaml 5.2 and the upcoming 5.3, currently in alpha.
• We're now publishing Windows Server 2022 Docker images to the OCaml Dockerhub. See for instance windows-server-msvc-ltsc2022-ocaml-4.14
• Dropped support for the post-LTS distro versions Debian 10 and 11, focusing our resources on the OCaml compiler's Tier 1 platform.

These updates ensure that our systems continue to support OCaml developers on a broad range of systems, in particular by testing package publication to the opam repository and publishing Docker images.

Opam Repository Publishing Experience

We've made improvements to enhance the experience of publishing packages to the opam repository:

• Implemented a linting check for package maintainer email addresses, ensuring package maintainers can be reliably contacted when needed.
• Mitigated solver timeout errors in the opam repo CI system, reducing frustrating delays in the package publishing process.
• Fixed an uncaught exception that sometimes occurred during linting checks in the opam repo CI.
• Improved error reporting and added instructions for running lint checks locally, making it easier for package authors to identify and resolve issues before submitting to the repository.
• We are generating documentation of the platforms under test in opam CI, allowing package authors a clear overview of the extensive build matrix we are providing.

We hope these changes will make package publication experience smoother. We're committed to improving the experience for newcomers and existing repository contributors alike, stay tuned for more improvements!

Security and Reliability

Maintaining the security and reliability of the OCaml infrastructure remains a top priority:

• Updated our systems to address CVE-2024-6387.
• We maintained 99.9% availability for the opam repo CI over the last two months, providing a stable and reliable service for the OCaml community.

Forging Ahead

Much has been done but much more is in the works! Expect updates more regularly going forward, and don't hesitate to reach out on ocaml/infrastructure/issues or discuss.ocaml.org if you have questions, requests, or ideas!

Related Changes

• Added continuous deployment for service configuration (by @mtelvers, https://github.com/ocurrent/ocurrent-configurator)
• Implemented linting for package maintainer email addresses (by @punchagan, https://github.com/ocurrent/opam-ci-check/pull/30)
• Mitigated solver timeout errors in opam repo CI (by @mtelvers and @shonfeder, https://github.com/ocaml/infrastructure/issues/147)
• Fixed uncaught exception in opam repo CI linting checks (by @shonfeder, https://github.com/ocurrent/opam-repo-ci/pull/341)
• Updated systems to address CVE-2024-6387 (by @mtelvers, https://github.com/ocaml/infrastructure/issues/140)
• Added support for OCaml 5.2 and 5.3 (by @mtelvers, https://github.com/ocurrent/opam-repo-ci/issues/268 and https://github.com/ocurrent/opam-repo-ci/issues/363)
• Improved Windows support (by @mtelvers, https://github.com/ocurrent/docker-base-images/issues/241)
• Added support for GCC 14 (by @mtelvers, https://github.com/ocurrent/docker-base-images/issues/279)
• Dropped support for Debian 10 and 11 (by @mtelvers and @shonfeder, https://github.com/ocurrent/ocaml-dockerfile/pull/220 and https://github.com/ocurrent/ocaml-dockerfile/pull/210)
• Generated documentation of CI test platforms and deployed services (by @benmandrew, https://github.com/ocurrent/opam-repo-ci/blob/master/doc/platforms.md and https://github.com/ocurrent/ocurrent-deployer/blob/master/doc/services.md)
• Improved error reporting and local lint check instructions in opam CI (by @punchagan, https://github.com/ocurrent/opam-repo-ci/issues/359 and https://github.com/ocurrent/opam-repo-ci/issues/360)

We are happy to announce the joint release of Merlin 5.2.1-502 and 4.17.1. This release adds many new features to Merlin including the ability to add hints to a source tree, serch for values using a type signature and expanding PPX annotations to preview their source code. There are also bug fixes for both the Merlin binary and editor modes.

More information can be found in the Discuss announcement.

Contributions are always welcome at Merlin | Issues

Hello folks! 👋

We'd like to welcome everyone to try and play with the Dune Developer Preview! 🎉

This experimental nightly release of dune includes a lot of improvements, including the much expected package management features, and it can be installed from that website or by using the new installation script:

$ curl -fsSL https://get.dune.build/install | bash

In a few seconds you should be ready to OCaml by calling dune:

You can also watch and share this demo on X and Mastodon.

Please try it out and let us know what you think 🙏

📅 You can book a feedback call with us here

📝 You can submit feedback using this form

🐛 You can submit issues to Github on ocaml/dune

Changes since last update

The Dune shared cache has been enabled by default. We're starting off by caching all downloads and dependencies.

We have improved support for dev tools. We're working to streamline this but in the latest binary you can:

• Configure your LSP (in Neovim, Vim, Emacs, etc) to call dune tools exec ocamllsp to get LSP support for your projects out of the box – this may take a little bit the first time it builds the LSP for a compiler version, but it's pretty much instant afterwards.

• Call dune fmt to get your project formatted – remember to add an .ocamlformat file if you don't have one yet. An empty one is enough.

• Call dune ocaml doc to get documentation built

What's next?

We're looking forward to streamlining the DX, working on better dependency locks, and looking into supporting Windows.

In particular, we're considering work on a few things:

• dune create <repo> – to let the community create templates that can be easily used from within dune
• dune pkg fetch – to prefetch packages and prepare a repository for working in offline mode
• dune build @deps - to build all dependencies, useful for staged builds in Dockerfiles
• dune pkg add <name> - to make adding packages straightforward
• a short-hand syntax for pins on github
• and more!

If you've got any ideas, we'd love to hear them, so please open a feature request on Github 🙏

Other updates

FunOCaml Presentation

At FunOCaml we had a last-minute opportunity to present the work being done on Dune and we used it to introduce the Developer Preview to the community, and even tested Package Management live with suggestions from the audience (thanks @anmonteiro and Paul-Elliot for participating!) – you can watch it on Twitch.

New design

We're working with @Claire_Vandenberghe on redesigning the Developer Preview website so that it'd feel like a seamless extension of OCaml.org – in this current iteration we've made it easier to get started and we're putting the FAQ front and center.

We'll be iterating on this design in the coming weeks until it fits perfectly within the OCaml.org design system 🎨

You can check the new website here: https://preview.dune.build

Upcoming Blog posts

In the near future we'll be publishing blog posts about the Developer Preview and Package Management, which we're working on with @professor.rose 👏

Four months after the release of OCaml 5.2.0, the set of new features for the future version 5.3.0 of OCaml has been frozen. We are thus happy to announce the first alpha release for OCaml 5.3.0.

This alpha version is here to help fellow hackers join us early in our bug hunting and opam ecosystem fixing fun (see below for the installation instructions). More information about the whole release process is now available in the compiler repository, and we will try to propagate this information to ocaml.org shortly.

The progresses on stabilising the ecosystem are tracked on the opam readiness for 5.3.0 meta-issue.

The full release is expected around November, see the new prospective calendar for more information.

If you find any bugs, please report them on OCaml's issue tracker.

If you are interested in the ongoing list of new features and bug fixes, the updated change log for OCaml 5.3.0 is available on GitHub.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.3.0~alpha1

The source code for the alpha is also available at these addresses:

• GitHub
• OCaml archives at Inria

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.3.0~alpha1+options <option_list>

where option_list is a space separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.3.0~alpha1+flambda+nffa ocaml-variants.5.3.0~alpha1+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

Feedback on this post is welcomed on Discuss!

As mentioned in our talk at the OCaml Workshop 2024, we decided to switch to a time-based release cycle (every 6 months), starting with opam 2.3.

As promised, we are happy to announce the first alpha release of opam 2.3.0. You can view the full list of changes in the release note.

This version is an alpha, we invite users to test it to spot previously unnoticed bugs as we head towards the stable release.

Major breaking change

When loading a repository, opam now ignores files in packages' files/ directories which aren't listed in the extra-files field of the opam file. This was done to simplify the opam specification where we hope the opam file to be the only thing that you have to look at when reading a package specification. The optionality of the extra-files: field goes against that principle. This change also reduces the surface area for potential file corruption as it ensures that extra-files are checked against their checksums.

This is a breaking change and means that if you are using the files/ directory without the extra-files: field, you need to make sure that all files in that directory are listed in the extra-files field. Once done, the resulting opam file is backward-compatible and you don't need to worry about anything else.

If you have an opam repository, you should make sure all files are listed so every packages continues to work without any issue, which can be done automatically using the opam admin update-extrafiles command.

Major changes

• Packages requiring an unsupported version of opam are now marked unavailable, instead of causing a repository error. This means an opam repository can now allow smoother upgrade in the future where some packages can require a newer version of opam without having to fork the repository to upgrade every package to that version as was done for the upgrade from opam 1.2 to 2.0

• Add a new opam list --latests-only option to list only the latest versions of packages. Note that this option is respects the order options were given on the command line. For example: --available --latests-only will first list all the available packages, then choose only the latest packages in that set; while --latests-only --available will first list all the latest packages, then only show the ones that are available in that set

• Fix and improve opam install --check, which now checks if the whole dependency tree of the package is installed instead of only the root dependencies

• Add a new --verbose-on option to enable verbose output for specified package names. Thanks to @desumn for this contribution

• Add a new opam switch import --deps-only option to install only the dependencies of the root packages listed in the opam switch export file

• opam switch list-available will now not display compilers flagged with avoid-version/deprecated unless --all is given, meaning that the "trunk" build of OCaml no longer appears to be the latest version

• opam switch create --repos now accepts git URLs suffixed with .git instead of requiring the git+https:// protocol prefix. This is consistant with other commands such as opam repository add. Thanks to @Keryan-dev for this contribution

• opam switch set-invariant now displays the switch invariant using the same syntax as the --invariant flag

• The builtin-0install solver was improved and should now be capable of being your default solver instead of builtin-mccs+glpk. It was previously mostly only suited for automated tasks such as Continuous Integration. If you wish to give it a try, simply call opam option solver=builtin-0install

• Most of the unhelpful conflict messages were fixed

• Fix the value of the arch variable when the current OS is 32bit on a 64bit machine (e.g. Raspberry Pi OS)

• opam now fails when git submodules fail to update instead of ignoring the error and just showing a warning

• opam's libraries now compile with OCaml >= 5.0 on Windows

Various performance and other improvements were made and bugs were fixed. API changes are denoted in the release note linked above. This release also includes a handful of PRs improving the documentation and more two dozen PRs improving and extending the tests.

Try it!

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.3.0~alpha1"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) } -Version 2.3.0~alpha1"

or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Happy hacking!

We're happy to announce the release of Odoc 2.4.3!

This release includes three key fixes: we restored missing KaTeX headers for proper mathematical rendering, resolved an issue where ][ characters in code blocks were incorrectly interpreted as "code blocks with result" (now requiring explicit delimiters), and corrected the misprinting of type variables from ML files in OCaml 4.14 and later versions where multiple instances of the same type variable could be displayed with different names.

As we prepare for the public beta, we're ramping up the DX interviews and ensuring the first few users will have a fun, productive experience with the Developer Preview.

📥 If you signed up for the Dev Preview back in May, check your inbox for a link and instructions to schedule your DX interview with us.

Here's a sample video on (Mastodon or X) where you can see us building the Riot project on a machine that does not have OCaml installed. It is pretty neat!

Seriously, big shoutout to the Dune team at Tarides[0] and Jane Street[1] who have been doing a phenomenal job 👏 ✨ 🐫

So here's what getting started with OCaml looks like using the Dune Developer Preview as of today (August 19 2024):

1. get dune from our binary distribution – we'll soon make this public!
2. run dune pkg lock in your favorite project
3. run dune build

That's it. No need to install anything else! Dune will see that lock file, fetch, and build all necessary dependencies.

🗺️ These are some strong steps towards the OCaml Platform vision for 2026 that we are actively working towards. If you have any thoughts or feedback please let us know!

There are more improvements coming that will help remove friction to get started and create a delightful experience. Both of these things we strongly believe will help onboard new users to the OCaml world.

Here's a few in the works:

• Various DX improvements – from new outputs to simplified workflows, we want to make using Dune just delightful.

• Bundled support for dev tools (OCamlFormat, odoc, LSP) – the default toolset will be available without any extra steps! Just call dune fmt and it works. No need to manually install anything else.

• Automatic dependency locking – when building, and even in watch mode, Dune will lock your dependencies by default and keep the lock up to date.

• Cross-project caching – by default we'll enable a local Dune cache across the system, so you never rebuild the same dependency, even across projects.

• Signed binaries with certificates of origin – we care deeply about security and want to make sure that any binary we ship can be easily verified and tracked back to its sources.

Stay tuned! 👋

PS: here's a longer video on (Mastodon or X) showing you the setup for OCaml from zero, creating a new project, and adding a dependency, all within ~5 minutes

[0] @emillon @Leonidas @gridbugs @tmattio @maiste . Ambre Suhamy, Alpha Diallo [1] @rgrinberg

Feedback on this post is welcomed on Discuss!

We are pleased to announce the release of opam 2.2.1.

We've fixed a couple of regressions and would like to encourage users of opam 2.2 to upgrade.

Changes

The three main changes are:

• Fixe a regression in opam install --deps-only where the direct dependencies were not set as root packages (spotted in the wild by @rjbou and also reported on Discuss)
• Fix a regression when fetching Git packages where the resulting Git repository could lead to unexpected outputs of Git commands, by disabling shallow clone by default except when fetching opam repositories (#6145)
• Mitigate curl/curl#13845 by falling back from --write-out to --fail if exit code 43 is returned by Curl. In particular, this fixes opam init when run from cmd/PowerShell on Windows 11 23H2 (#6120)

A couple more improvements and additions to the testsuite were made. You can view the full list of changes in the release note.

Try it!

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.2.1"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) }"

(or via winget upgrade OCaml.opam) or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Happy hacking!

We're happy to announce the release of opam-publish 2.4.0!

We are pleased to announce the release of OCaml LSP 1.19.0. This version brings official support for OCaml 5.2. It also includes a new custom query to get

documentation and a fix regarding the handling of OCamlFormat processes.

The Ppxlib dev team is happy to announce the release of ppxlib.0.33.0.

This release's main feature is a series of improvement to flags controlling unused value/module/type warnings silencing. The ppxlib driver generates warning silencing items to prevent [@@deriving ...] generated code to trigger unused code warnings. Three warnings are disabled that way:

• Warning 32: unused value
• Warning 60: unused module
• Warning 34: unused type The first two are disabled for values and modules generated by the deriver while the third is disabled for the types in the type declaration to which the [@@deriving ...] attribute is attached. This feature was added a long time ago to avoid manually disabling those warnings when working with derivers that generate a set of values and modules only to use a subset of those. Alternatively, the unused type warning silencing was added to allow defining an alias type only to be consumed by a deriver (e.g., type error = [`Not_found | `Invalid_arg] [@@deriving to_string]). We since then believe that we should not disable warnings lightly, as this behaviour makes it difficult to find and remove deadcode. The right approach in those situations should be to fix the PPX derivers so that they are more configurable and can be used without triggering such warnings. We will start to move toward removing this feature, but since it is still useful in some places, we came up with a plan to do this iteratively. In ppxlib.0.31.0 we added the -unused-code-warnings driver flag and the ?unused_code_warnings Deriving.V2.make optional argument to control whether to silence Warnings 32 and 60. When both are set to true, by the user and the deriver authors, the warnings are not silenced. As of ppxlib.0.33.0, these also control the silencing of Warning 34 (unused type). force can now be passed to the -unused-code-warnings flag in order to disable warnings silencing, regardless of the derivers opting in. This allows users to test whether their codebase and their set of derivers rely on warning silencing or not and to use those results to eliminate deadcode and/or report issues upstream to the derivers they use. We also added a separate -unused-type-warnings flag that works similarly to -unused-code-warnings (i.e., depends on the value of the ?unused_code_warnings argument), but it only controls Warning 34 silencing, as it turns out it is less likely to cause unwanted warnings than with the other two. This will allow users to disable it more easily, without having to deal with Warnings 32 and 60 straight away. We want to encourage users to try those on their codebase in order to see the impact it has. Did you have deadcode lying around that slipped past undetected? Does this trigger unwanted warnings because of deriver's generated code? The plan is to give the ecosystem some time to try those features and adapt by fixing individual derivers and flipping setting ?unused_code_warnings to true as they do. After a while, we will swap the default value of the driver flag to true so that only derivers that haven't opted in will enable warning silencing. Then as time goes we will swap the default of the Deriving.make argument so that derivers will instead have to explicitly opt out to get the warning silencing. Finally, once we are confident the ecosystem is in a good enough state, we will remove this feature altogether.

ppxlib.0.33.0 also comes with a couple of new features for PPX authors:

• A couple new Ast_builder functions: elist_tail and plist_tail that can be used to build list expressions and patterns with a custom tail: elist_tail [expr1; expr2] tail_expr returns the expression for expr1::expr2::tail_expr.
• Context_free.special_function', a new version of special_function that allows passing a Longident.t directly rather that relying on parsing the string argument to a Longident.t.

Finally, the release includes a few bug fixes to Longident.parse and Code_path.main_module_name and fixes the location-check flag so it is not required to also pass -check to enable location checks. It also fixes the 5.2 migrations locations, as we used to build nodes with inconsistent locations when migrating Pexp_function nodes.

We would like to thank our external contributors who have been a huge part of this release: @octachron, @vg-b, and @jchavarri, and a special mention to @mbarbin, who has not only contributed a lot to the warning silencing features but has been extensively testing and providing very useful feedback on them.

And of course, as usual, we'd like to thank the OCaml Software Foundation who has been funding my work on Ppxlib and on this release, making all of this possible!

We are pleased to announce the release of OCaml LSP 1.18.0. This version comes with a lot of fixes and new features.

Notable features that are included in this release are:

• Improved hover behavior with less noisy hovers on some parse tree nodes such as keywords, comments, etc., along with support for hovering over PPX annotations and preview the generated code.
• Some additional custom queries, particularly TypeEnclosing
• Folding ifthenelse expressions
• A new configuration option to control Dune diagnostics
• Improved document symbols

...and many fixes to a handful of issues.

Feedback is very much welcomed on the the Discuss Announcement post and do not hesistate to report issues in the issue tracker.

We're happy to announce the release of opam-publish 2.3.1!

Feedback on this post is welcomed on Discuss!

We are very pleased to announce the release of opam 2.2.0, and encourage all users to upgrade. Please read on for installation and upgrade instructions.

Try it!

In case you plan a possible rollback, you may want to first backup your ~/.opam or $env:LOCALAPPDATA\opam directory.

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.2.0"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) }"

or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Changes

Major change: Windows support

After 8 years' effort, opam and opam-repository now have official native Windows support! A big thank you is due to Andreas Hauptmann (@fdopen), whose WODI and OCaml for Windows projects were for many years the principal downstream way to obtain OCaml on Windows, Jun Furuse (@camlspotter) whose initial experimentation with OPAM from Cygwin formed the basis of opam-repository-mingw, and, most recently, Jonah Beckford (@jonahbeckford) whose DkML distribution kept - and keeps - a full development experience for OCaml available on Windows.

OCaml when used on native Windows requires certain tools from the Unix world which are provided by either Cygwin or MSYS2. We have engineered opam init so that it is possible for a user not to need to worry about this, with opam managing the Unix world, and the user being able to use OCaml from either the Command Prompt or PowerShell. However, for the Unix user coming over to Windows to test their software, it is also possible to have your own Cygwin/MSYS2 installation and use native Windows opam from that. Please see the previous blog post for more information.

There are two "ports" of OCaml on native Windows, referred to by the name of provider of the C compiler. The mingw-w64 port is GCC-based. opam's external dependency (depext) system works for this port (including providing GCC itself), and many packages are already well-supported in opam-repository, thanks to the previous efforts in opam-repository-mingw. The MSVC port is Visual Studio-based. At present, there is less support in this ecosystem for external dependencies, though this is something we expect to work on both in opam-repository and in subsequent opam releases. In particular, it is necessary to install Visual Studio or Visual Studio BuildTools separately, but opam will then automatically find and use the C compiler from Visual Studio.

Major change: opam tree / opam why

opam tree is a new command showing packages and their dependencies with a tree view. It is very helpful to determine which packages bring which dependencies in your installed switch.

$ opam tree cppo
cppo.1.6.9
├── base-unix.base
├── dune.3.8.2 (>= 1.10)
│   ├── base-threads.base
│   ├── base-unix.base [*]
│   └── ocaml.4.14.1 (>= 4.08)
│       ├── ocaml-base-compiler.4.14.1 (>= 4.14.1~ & < 4.14.2~)
│       └── ocaml-config.2 (>= 2)
│           └── ocaml-base-compiler.4.14.1 (>= 4.12.0~) [*]
└── ocaml.4.14.1 (>= 4.02.3) [*]

Reverse-dependencies can also be displayed using the new opam why command. This is useful to examine how dependency versions get constrained.

$ opam why cmdliner
cmdliner.1.2.0
├── (>= 1.1.0) b0.0.0.5
│   └── (= 0.0.5) odig.0.0.9
├── (>= 1.1.0) ocp-browser.1.3.4
├── (>= 1.0.0) ocp-indent.1.8.1
│   └── (>= 1.4.2) ocp-index.1.3.4
│       └── (= version) ocp-browser.1.3.4 [*]
├── (>= 1.1.0) ocp-index.1.3.4 [*]
├── (>= 1.1.0) odig.0.0.9 [*]
├── (>= 1.0.0) odoc.2.2.0
│   └── (>= 2.0.0) odig.0.0.9 [*]
├── (>= 1.1.0) opam-client.2.2.0~alpha
│   ├── (= version) opam.2.2.0~alpha
│   └── (= version) opam-devel.2.2.0~alpha
├── (>= 1.1.0) opam-devel.2.2.0~alpha [*]
├── (>= 0.9.8) opam-installer.2.2.0~alpha
└── user-setup.0.7

Special thanks to @cannorin for contributing this feature.

Major change: with-dev-setup

There is now a way for a project maintainer to share their project development tools: the with-dev-setup dependency flag. It is used in the same way as with-doc and with-test: by adding a {with-dev-setup} filter after a dependency. It will be ignored when installing normally, but it's pulled in when the package is explicitly installed with the --with-dev-setup flag specified on the command line.

For example

opam-version: "2.0"
depends: [
  "ocaml"
  "ocp-indent" {with-dev-setup}
]
build: [make]
install: [make "install"]
post-messages:
[ "Thanks for installing the package"
  "as well as its development setup. It will help with your future contributions" {with-dev-setup} ]

Major change: opam pin --recursive

When pinning a package using opam pin, opam looks for opam files in the root directory only. With recursive pinning, you can now instruct opam to look for .opam files in subdirectories as well, while maintaining the correct relationship between the .opam files and the package root for versioning and build purposes.

Recursive pinning is enabled by the following options to opam pin and opam install:

• With --recursive, opam will look for .opam files recursively in all subdirectories.
• With --subpath <path>, opam will only look for .opam files in the subdirectory <path>.

The two options can be combined: for instance, if your opam packages are stored as a deep hierarchy in the mylib subdirectory of your project you can try opam pin . --recursive --subpath mylib.

These options are useful when dealing with a large monorepo-type repository with many opam libraries spread about.

New Options

• opam switch -, inspired by git switch -, makes opam switch back to the previously selected global switch.

• opam pin --current fixes a package to its current state (disabling pending reinstallations or removals from the repository). The installed package will be pinned to its current installed state, i.e. the pinned opam file is the one installed.

• opam pin remove --all removes all the pinned packages from a switch.

• opam exec --no-switch removes the opam environment when running a command. It is useful when you want to launch a command without opam environment changes.

• opam clean --untracked removes untracked files interactively remaining from previous packages removal.

• opam admin add-constraint <cst> --packages pkg1,pkg2,pkg3 applies the given constraint to a given set of packages

• opam list --base has been renamed into --invariant, reflecting the fact that since opam 2.1 the "base" packages of a switch are instead expressed using a switch invariant.

• opam install --formula <formula> installs a formula instead of a list of packages. This can be useful if you would like to install one package or another one. For example opam install --formula '"extlib" |"extlib-compat"' will install either extlib or extlib-compat depending on what's best for the current switch.

Miscellaneous changes

• The UI now displays a status when extracting an archive or reloading a repository
• Overhauled the implementation of opam env, fixing many corner cases for environment updates and making the reverting of package environment variables precise. As a result, using setenv in an opam file no longer triggers a lint warning.
• Fix parsing pre-opam 2.1.4 switch import files containing extra-files
• Add a new sys-ocaml-system default global eval variable
• Hijack the "%{var?string-if-true:string-if-false-or-undefined}%" syntax to support extending the variables of packages with + in their name (conf-c++ and conf-g++ already exist) using "%{?pgkname:var:}%"
• Fix issues when using fish as shell
• Sandbox: Mark the user temporary directory (as returned by getconf DARWIN_USER_TEMP_DIR) as writable when TMPDIR is not defined on macOS
• Add Warning 69: Warn for new syntax when package name in variable in string interpolation contains several '+' (this is related to the "hijack" item above)
• Add support for Wolfi OS, treating it like Alpine family as it also uses apk
• Sandbox: /tmp is now writable again, restoring POSIX compliance
• Add a new opam admin: new add-extrafiles command to add/check/update the extra-files: field according to the files present in the files/ directory
• Add a new opam lint -W @1..9 syntax to allow marking a set of warnings as errors
• Fix bugs in the handling of the OPAMCURL, OPAMFETCH and OPAMVERBOSE environment variables
• Fix bugs in the handling of the --assume-built argument
• Software Heritage fallbacks is now supported, but is disabled-by-default for now. For more information you can read one of our previous blog post

And many other general and performance improvements were made and bugs were fixed. You can take a look to previous blog posts. API changes and a more detailed description of the changes are listed in:

• the release note for 2.2.0~alpha
• the release note for 2.2.0~alpha2
• the release note for 2.2.0~alpha3
• the release note for 2.2.0~beta1
• the release note for 2.2.0~beta2
• the release note for 2.2.0~beta3
• the release note for 2.2.0~rc1
• the release note for 2.2.0

This release also includes PRs improving the documentation and improving and extending the tests.

Please report any issues to the bug-tracker.

We hope you will enjoy the new features of opam 2.2! 📯

We are pleased to announce the release of Merlin 5.1-502. This is an important release that brings a lot of backend changes and a major new feature: project-wide occurrences queries.

Try it by running dune build @ocaml-index (since dune 3.16.0) and performing a reference query!

More information can be found in the discuss announcement and the wiki.

Feedback on this post is welcomed on Discuss!

We are very excited to announce the first (and hopefully only) release candidate for opam 2.2.0.

We've squashed a few more bugs and we consider this to be ready for the final release. You can view the full list of changes in the release note.

We invite users to test it one final time just in case there are any previously unnoticed bugs!

Changes

• Fix opam upgrade wanting to keep rebuilding the compiler (as now it contains an x-env-path-rewrite field)
• Provide defaults so opam init -y no longer asks questions on Windows
• Fix OpamConsole.menu when there are more than 9 options (can happen on Windows)

A couple more improvements were made and bugs were fixed. The single API change is also denoted in the release note. This release also includes PRs extending the tests.

Try it!

In case you plan a possible rollback, you may want to first backup your ~/.opam or $env:LOCALAPPDATA\opam directory.

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.2.0~rc1"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) }"

or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Thanks for trying this new release out, and we hope you will enjoy the new features of opam 2.2!

We're happy to announce the release of Dune 3.16.0.

Among the list of chances, this release contains improvements to Melange support and a way to look for references in a whole project using Merlin and OCaml LSP.

We are pleased to announce the release of Merlin 4.16-414 and 4.16-501.

These releases expose additional functions for packages using merlin-lib that need to manually parse merlin commands.

Feedback on this post is welcomed on Discuss!

We are very pleased to announce the third and final beta release of opam 2.2.0.

We've done our best to polish everything and squash as many bugs as possible in order to be ready for the final release. You can view the full list of changes in the release note.

This version is a beta, we invite users to test it to spot previously unnoticed bugs as we near the stable release.

Changes

• Greatly enhance the opam init user experience on Windows, and the number of recognised configurations
• New option opam init --cygwin-extra-packages=CYGWIN_PKGS --cygwin-internal-install, to specify additional packages for the internal Cygwin installation
• Redirect the opam root to C:\opamroot\opam-xxx when the opam root contains spaces on Windows
• Out-of-the-box UTF-8 paged --help on Windows
• Fix a performance regression when calling opam install --deps-only on an already installed package
• Fix several edge cases related to environment reverting
• Fixed some issues that could appear when upgrading from previous versions of opam
• Fix various issues with opam tree --with-test
• Fix parsing opam 2.1 switch import files containing extra-files
• Fix download URLs containing invalid characters on Windows
• Fix some failure cases when extracting tarballs which contain symlinks on Windows

Various other general and performance improvements were made and bugs were fixed. API changes are denoted in the release note. This release also includes PRs improving the documentation and improving and extending the tests.

Try it on Windows!

BEWARE: the command shown below is experimental, use caution and please do report any issues that you are experiencing. If you prefer to not use our experimental script, feel free to get the Windows binary directly from the Release Page and put it in your directory of choice instead.

Now that the Windows support was merged in opam-repository, testing is as simple as calling the following command from a PowerShell terminal:

Invoke-Expression "& { $(Invoke-RestMethod https://raw.githubusercontent.com/kit-ty-kate/opam/windows-installer/shell/install.ps1) }"

opening a new terminal, and a simple opam init will work out-of-the-box.

Try it on other platforms!

In case you plan a possible rollback, you may want to first backup your ~/.opam directory.

The upgrade instructions are unchanged:

1. Either from binaries: run

   bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.2.0~beta3"
   

   or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Thanks for trying this new release out, and we hope you will enjoy the new features!

We are pleased to announce the release of Merlin 4.15-414 and 4.15-501.

These releases bring a handful of bug fixes and improvements, notably to the destruct feature, that were already released for OCaml 5.2 in Merlin 5.0-502.

We just released version 3.15.3 with some bug fixes.

Feedback on this post is welcomed on Discuss!

We are pleased to announce the patch release of opam 2.1.6.

This opam release consists of backported bug fixes and improvements:

• Changes necessary for opam-repository (see ocaml/opam-repository#23789)
  • Warn if GNU patch is not detected when a patch is applied (#5893)
  • Use gpatch by default instead of patch on NetBSD and DragonFlyBSD (#5893)
  • Use gpatch if it exists and is detected as GNU patch when patch is not GNU patch (#5893)
• Better recognize depexts on Gentoo, NetBSD, OpenBSD (#5065)
• Upgrade the vendored dune to 3.14.0 (#5869)
• Fix debug logs showing up regardless of verbosity on macOS 12.7.1 / 13.6.3 / 14.2 and FreeBSD (#5769)

Opam installation instructions (unchanged):

1. From binaries: run

   bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.1.6"
   

   or download manually from the Github "Releases" page to your PATH. In this case, don't forget to run opam init --reinit -ni to enable sandboxing if you had version 2.0.0~rc manually installed or to update you sandbox script.

2. From source, using opam:

   opam update; opam install opam-devel
   

   (then copy the opam binary to your PATH as explained, and don't forget to run opam init --reinit -ni to enable sandboxing if you had version 2.0.0~rc manually installed or to update your sandbox script)

3. From source, manually: see the instructions in the README.

We hope you enjoy this new minor version, and remain open to bug reports and suggestions.

We are pleased to announce the release of Merlin 5.0-502!

This release brings official support for OCaml 5.2. Substantial backend changes were required to adapt to this release, especially for features such as occurrences and get-documentation. Do not hesitate to report any suspicious behavior in the issue tracker!

This release also fixes a handful of issues, two of them improving the behaviour of Merlin's destruct feature.

We have the pleasure of celebrating Inge Lehmann's birthday by announcing the release of OCaml version 5.2.0.

Some of the highlights in OCaml 5.2.0 are:

• Reintroduced GC compaction
• Restored native backend for POWER 64 bits
• Thread sanitiser support
• New Dynarray module
• New -H flag for hidden include directories
• Project-wide occurrence metadata support for developer tools
• Raw identifiers
• Local open in type expressions

And a lot of incremental changes:

• Around 20 new functions in the standard library
• Many fixes and improvements in the runtime
• Many bug fixes

OCaml 5.2.0 is still a somewhat experimental release compared to the OCaml 4.14 branch. In particular:

• The Windows MSVC port is still unavailable.
• Ephemeron performances need to be investigated.
• statmemprof is being tested in the developer branch.
• There are a number of known runtime concurrency or GC performance bugs (that trigger under rare circumstances).

Since the Windows MSVC port and statmemprof are still missing, the maintenance support for OCaml 4.14 will be extended until at least the end of the year.

Please report any unexpected behaviours on the OCaml issue tracker and post any questions or comments you might have on our discussion forums.

The full list of changes can be found in the changelog below.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands:

opam update
opam switch create 5.2.0

The source code for the release candidate is also directly available on:

• GitHub
• OCaml archives at Inria

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.2.0+options <option_list>

where <option_list> is a space separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.2.0+flambda+nffa ocaml-variants.5.0.0+options ocaml-option-flambda ocaml-option-no-flat-float-array

The release of OCaml 5.2.0 is imminent. As a final step, we are publishing a release candidate to check that everything is in order before the release in the upcoming week(s).

If you find any bugs, please report them on OCaml's issue tracker.

Compared to the second beta, this release contains one small compiler-libs printer fix and one configuration tweak.

The full change log for OCaml 5.2.0 is available on GitHub. A short summary of the changes since the second beta release is also available below.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.2.0~rc1

The source code for the release candidate is also directly available on:

• GitHub
• OCaml archives at Inria

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.2.0~rc1+options <option_list>

where <option_list> is a space-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.2.0~rc1+flambda+nffa ocaml-variants.5.2.0~rc1+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

The ppxlib team is happy to announce the release of ppxlib.0.32.1.

The main feature of this release is of course the support for the upcoming OCaml 5.2 release. Starting with this version you'll be able to use ppx with the latest compiler.

The feature also comes with a small follow up improvement to the 0.32.0 error reporting changes that simplifies how exception thrown from context free rewriting are handled. The errors will now be inserted where the generated code would have been instead of appended to the whole AST. This should lead to a better error reporting from the compiler as it will now report errors in order of their position in the code.

We'd like to thank the OCaml Software Foundation once again as they funded the vast majority of the work for this release.

We've released odoc 2.4.2 with OCaml 5.2 compatibility and a few bug fixes.

We've released OCamlFormat 0.26.2 with compatibility with OCaml 5.2.

We just released version 3.15.2 with some bug fixes.

This one is particularly important for Coq users since it fixes a bug introduced in 3.13.0 that made incremental builds very slow.

attempt at monorepo

Last week, we merged an update to the compiler-libs "shape" API for querying definition information from the compiler.

Unfortunately, this small change of API breaks compatibility with at least odoc. Generally, we try to avoid this kind of changes during the beta releases of the compiler. However, after discussions we concluded that it will be easier on the long term to fix the API right now in order to avoid multiplying the number of supported versions of the shape API in the various OCaml developer tools .

We have thus released a second beta version of OCaml 5.2.0 to give the time to developer tools to update their 5.2.0 version ahead of the release (see below for the installation instructions).

Beyond this changes of API, the new beta contains three more bug fixes and three documentation updates, which is a good sign in term of stability.

As usual, you can follow the last remaining compatibility slags on the opam readiness for 5.2.0 meta-issue.

If you find any bugs, please report them on OCaml's issue tracker.

Currently, the release is planned for the beginning of May.

If you are interested in full list of features and bug fixes of the new OCaml version, the updated change log for OCaml 5.2.0 is available on GitHub.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 5.2.0~beta2

The source code for the beta is also available at these addresses:

• GitHub
• OCaml archives at Inria

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.2.0~beta2+options <option_list>

where option_list is a space-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.2.0~beta2+flambda+nffa ocaml-variants.5.2.0~beta2+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

This release reverts the change introduce in Mdx 2.4.0 that allows the execution of included OCaml code blocks after users reported issues. We will revisit the feature to ensure it is opt-in and doesn't break users setup.

Feedback on this post is welcomed on Discuss!

We are indescribably thrilled to announce the second beta release of opam 2.2.0.

It contains everything required to be able to make opam-repository compatible with Windows, as well as a whole bunch of fixes. You can view the full list of changes in the release note.

We'll post another blog post very soon with more directions on how to test opam on Windows with this release.

This version is a beta, we invite users to test it to spot previously unnoticed bugs as we head towards the stable release.

Changes

Windows support

This beta introduces a handful of changes necessary to be able to make the default opam-repository support Windows out of the box:

• Add a new sys-ocaml-system init default global eval variable
• Hijack the "%{var?string-if-true:string-if-false-or-undefined}%" syntax to support extending the variables of packages with + in their name (conf-c++ and conf-g++ already exist) using "%{?pgkname:var:}%"
• Add winsymlinks:native to the CYGWIN environment variable when installing a package on Windows. In particular, this provides a workaround when extracting ocamlbuild's sources.
• Internal Cygwin installation's bin directory is placed as far down PATH as is necessary not to shadow bash, tar, sort or git
• Disable ACL in Cygwin internal install to avoid permission mismatch errors

We expect to be able to show the proposed changed to opam-repository very soon to take advantage of all these changes.

opam-repository scalability

The current draft resolution resulting from the discussion in ocaml/opam-repository#23789 about the scalability of opam-repository includes the removal of some packages. However currently, opam uses the patch system command to apply changes from a repository. The behaviour of that command is thus very important and it is a known behaviour for the macOS and BSDs patch command to not be able to delete files which leads to failures and inconsistencies for opam. Package managers on those platforms installing opam already make opam depend on GNU patch, however a certain number of people do not install opam via a system package manager (e.g. our own install script!) and end up using their system version of patch. This is in particular a problem on macOS as the name of the GNU patch command is not gpatch like on BSDs but simply patch when installed via Homebrew.

This issue is surprisingly tricky to fix, and after many trials and errors, we've decided to:

• Warn if GNU patch is not detected when a patch is applied
• Use gpatch by default instead of patch on NetBSD and DragonFlyBSD
• Use gpatch if it exists and is detected as GNU patch when patch is not GNU patch

These changes will make their way to the upcoming opam 2.1.6, in a few weeks.

Other noteworthy changes

• Recommend enabling Developer Mode on Windows. This allows the creation of symlinks without requiring elevation. Longer-term, the aim is that we should never require Developer Mode, but at the moment more things work with it than without it!
• Mark the internal Cygwin installation as recommended. Please don't try to maintain your own Cygwin install for use with opam unless you really know what you're doing!
• Fix MSYS2 support. For 2.2.0, the focus has been on Cygwin, so configuring opam to use MSYS2 is quite manual. Please note that even if opam can use a MSYS2 installation, it is not yet officially supported and opam repository is not yet MSYS2 compatible. Use opam with MSYS2 only if you really really know what you're doing!
• Fix issues when using fish
• Improve the internal Cygwin installation during init on Windows
• Unixify Windows paths in init shells scripts
• Disable Software Heritage fallback by default as there currently no CI job in opam-repository to check validity of proposed swhid regarding release archive (neither publication tools support) and some concerns were raised regarding the degree of trust of the hashing method used by Software Heritage (sha1).
• Make sure opam source --dev with git sources, clones the whole repository instead of using --depth=1
• Sandbox: Mark the user temporary directory (as returned by getconf DARWIN_USER_TEMP_DIR) as writable when TMPDIR is not defined on macOS
• Add Warning 69: Warn for new syntax when package name in variable in string interpolation contains several '+' (this is related to the "hijack" item above)
• Add support for Wolfi OS, treat it like Alpine family as it also uses apk
• Upgrade the vendored dune package to 3.14.2 to allow to compile opam when the environment contains unicode characters on Windows (in particular, this means opam now works if your username contains accented characters)
• Upgrade other vendored packages (cmdliner 1.2.0, re 1.11.0, ocamlgraph 2.1.0, opam-file-format 2.1.6)

Various other general and performance improvements were made and bugs were fixed. API changes are denoted in the release note. This release also includes PRs improving the documentation and improving and extending the tests.

Windows Support

As we've said above we're writing a separate blog post to present how to test this new release of opam on Windows.

Stay tuned!

Try it!

In case you plan a possible rollback, you may want to first backup your ~/.opam directory.

The upgrade instructions are unchanged:

1. Either from binaries: run

   bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.2.0~beta2"
   

   or download manually from the Github "Releases" page to your PATH.

2. Or from source, manually: see the instructions in the README.

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Thanks for trying this new release out, and we hope you will enjoy the new features!

We're happy to announce that Dune 3.15.0 is now available. This feature has many fixes and new features that you can find in the changelog.

There are a few new features that we would like to specially highlight.

Removal of previous limitations in many forms

Prior to Dune 3.15 there were a number of limitations where percent forms like %{env:...} could be used to expand to useful values. In this release, @rgrinberg put some effort to relax a lot of these restrictions where possible.

In the new version some of these limitations have been lifted, so for example {env:...} can be used in install stanzas (#10160).

Likewise there was no consistency where %{cma:...} or %{cmo:...} could be used. With #10169, these forms should work consistently everywhere.

Similarly the variables allowed in enabled_if fields have been expanded in #10250, from just allowing variables that can be computed from the context to now allowing all variables as long as expanding these variables does not introduce dependency cycles.

These relaxed rules can also be combined to enable a library depending on environment variables, e.g. (enabled_if %{env:ENABLE_LIBFOO=false})).

Overlapping names in different contexts

Continuing the theme of conditionally enabling or disabling code to be built, @jchavarri and @rgrinberg's work on #10220 makes it possible to have overlapping names between executable and melange.emit targets. This can be useful when a name is to be shared in different contexts (e.g. one context with native compilation and one emitting code for the browser).

Properly output UTF-8 encoded text when formatting

Dune does not assume an encoding of dune files, however when files were formatted the formatter would err on the safe side and escape bytes outside the ASCII range. This means that UTF-8 characters outside of ASCII would get escaped into decimal escape sequences.

This was especially annoying in places where the user would write natural language texts, which is common when defining Opam packages in dune-project files. For example a discussion of a paper by Paul Erdős, Peter Frankl, Vojtěch Rödl would upon reformatting be turned into Paul Erd\197\145s, Peter Frankl, Vojt\196\155 R\195\182, which does a disservice to these scientists and is hard to read.

Thanks to the work of @moyodiallo in #9728 starting with Dune 3.15 the original encoding will be preserved, so your package descriptions will be more readable.

We are happy to announce the release of MDX 2.4.0! This is the first release of MDX to be compatible with OCaml 5.2.

This release also comes with support for executing included OCaml code blocks.