OCaml Changelog

Read the latest releases and updates from the OCaml compiler, OCaml infrastructure and the OCaml Platform Tools.

Compiler Platform Developer Preview Infrastructure OCaml.org

Utop 2.13.1

11 Jul 2023

utop platform

The release of UTop 2.13.0 introduced a regression on Windows. We're releasing UTop 2.13.1 with a patch, and made UTop 2.13.0 unavailable on Windows.

See full changelog

Fix unavailable expunge on Windows (#447, @jonahbeckford)

In Dune 3.9.0, we added a feature that offloads some computations to background threads. Unfortunately, this has a bad interaction on macOS, where we fork processes to implement the RPC server and watch mode.

We marked Dune 3.9.0 unavailable on macOS, and released 3.9.1 with some mitigations: we don't offload these computations on macOS, and we only fork when necessary.

The plan for the next release is to stop forking processes on macOS.

See full changelog

Fixes

Disable background operations and threaded console on macOS and other Unixes where we rely on fork. (#8100, #8121, fixes #8083, @rgrinberg, @emillon)
Initialize async I/O thread lazily. (#8122, @emillon)

Utop 2.13.0

04 Jul 2023

utop platform

We're releasing version 2.13.0 of UTop! This version comes with a couple of bug fixes.

It also bumps the minimal required version of OCaml to 4.11.0 and removes deprecated values from the API.

See full changelog

Fix behavior of utop -stdin (#434, fixes #433, @tuohy)
Handle bounds with Zed.next_error (#442, @tmattio)
Load files from XDG directories (the legacy paths still work). (#431, @Skyb0rg007)
Remove deprecated values prompt_continue, prompt_comment, smart_accept, new_prompt_hooks, at_new_prompt (#427, @emillon)
Require OCaml 4.11.0 or newer. (#444, @emillon)

opam 2.2.0~alpha

04 Jul 2023

opam platform

Feedback on this post is welcomed on Discuss!

We are happy to announce the alpha release of opam 2.2.0. It contains numerous fixes, enhancements, and updates; including much-improved Windows support, addressing one of the most important pain points identified by the OCaml community. You can view the full list of changes in the release note.

This alpha release is a significant milestone, brought together by Raja Boujbel after years of work from the opam dev team (Raja Boujbel, David Allsopp, Kate Deplaix, Louis Gesbert, in a united OCamlPro/Tarides collaboration) with the help of many community contributors. We also thank Jane Street for their continued sponsorship.

This version is an alpha, so we invite users to test it to spot previously unnoticed bugs and work towards a stable release.

Windows Support

Opam 2.2 comes with native Windows compatibility. You can now use opam from your preferred Windows terminal! We rely on the Cygwin UNIX-like environment for Windows as a compatibility layer, but it is possible for a package to generate native executables.

The main opam repository is not Windows compatible at the moment, but existing work on a compatible repository (originally from @fdopen) and 32/64 bit mingw-w64 packages (by @dra27) is in the process of being merged. Before the final release, we expect it to be possible to run opam init and use the main opam-repository for Windows.

How to Test opam on Windows

This alpha requires a preexisting Cygwin installation. Support for full management of a local Cygwin environment inside of opam (so that it's as transparent as possible) is queued already and should be available in 2.2.0~alpha2 as the default option.

Check that you have all dependencies installed:

autoconf, make, patch, curl
MinGW compilers: mingw64-x86_64-gcc-g++, mingw64-i686-gcc-g++
Or if you want to use the MSVC port of OCaml, you'll need to install Visual Studio or Visual Studio Build Tools

Download & extract the opam archive
In the directory launch make cold
A coffee later, you now have an opam executable!
Start your preferred Windows terminal (cmd or PowerShell), and initialise opam with the Windows sunset repository:

opam init https://github.com/ocaml-opam/opam-repository-mingw

From here, you can try to install sunset repository packages. If any bug is found, please submit an issue. It will help opam repository maintainers to add Windows repository packages into the main repository.

Hint: if you use the MinGW compiler, don't forget to add to your PATH the path to libc dlls (usually C:\cygwin64\usr\x86_64-w64-mingw32\sys-root\mingw\bin). Or compile opam with make cold CONFIGURE_ARGS=--with-private-runtime, and if you change opam location, don't forget to copy Opam.Runtime.amd64 (or Opam.Runtime.i386) with it.

Recursive Pin

When installing or pinning a package using opam install or opam pin, opam normally only looks for opam files at the root of the installed package. With recursive pinning, you can now instruct opam to also look for .opam files in subdirectories, while maintaining the correct relationship between the .opam files and the package root for versioning and build purposes.

Recursive pinning is used with 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, give opam pin . --recursive --subpath mylib a try!

You can use these options with opam pin, opam install, and opam remove.

$ tree .
.
├── ba
│   └── z
│       └── z.opam
├── bar
│   └── bar.opam
└── foo.opam

$ opam pin . --subpath ba/z --no-action
Package z does not exist, create as a NEW package? [y/n] y
z is now subpath-pinned to directory /ba/z in git+file:///tmp/recpin#master (version 0.1)

$ opam pin --recursive . --no-action
This will pin the following packages: foo, z, bar. Continue? [y/n] y
foo is now pinned to git+file:///tmp/recpin#master (version 0.1)
Package z does not exist, create as a NEW package? [y/n] y
z is now subpath-pinned to directory /ba/z in git+file:///tmp/recpin#master (version 0.1)
Package bar does not exist, create as a NEW package? [y/n] y
bar is now subpath-pinned to directory /bar in file:///tmp/recpin (version 0.1)

$ opam pin
bar.0.1  (uninstalled)  rsync  directory /bar in file:///tmp/recpin
foo.0.1  (uninstalled)  git    git+file:///tmp/recpin#master
z.0.1    (uninstalled)  git    directory /ba/z in git+file:///tmp/recpin#master

$ opam pin . --recursive --subpath ba/ --no-action
Package z does not exist, create as a NEW package? [y/n] y
z is now subpath-pinned to directory /ba/z in git+file:///tmp/recpin#master (version 0.1)

Tree View

opam tree shows 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) [*]

It can also display a reverse-dependency tree (through opam why, which is an alias to opam tree --rev-deps). 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.

Recommended Development Tools

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 explicitely installed with the --with-dev-setup flag specified on the command line. The variable is also resolved in the post-messages: field to allow maintainers to share more informations about that setup.

This is typically useful for tools that are required for bootstrapping or regenerating artifacts.

For example

opam-version: "2.0"
depends: [
  "ocaml"
  "dune"
  "ocp-indent" {with-dev-setup}
]
build: [make]
install: [make "install"]
post-messages:
[ "Thanks for installing the package"
  "and its tool dependencies too, it will help for your futur PRs" {with-dev-setup} ]

Software Heritage Binding

Software Heritage is a project that aims to archive all software source code in existence. This is done by collecting source code with a loader that uploads software source code to the Software Heritage distributed infrastructure. From there, any project/version is available via the search webpage and via a unique identifier called the SWHID. Some OCaml source code is already archived, and the main opam and Coq repository packages are continuously uploaded.

Opam now integrates a fallback to Software Heritage archive retrieval, based on SWHID. If an SWHID URL is present in an opam file, the fallback can be activated.

To keep backwards compatibility of opam files, we added a specific Software Heritage URL syntax to the url.mirrors: field, which is used to specify mirrors of the main URL. Opam 2.2.+ understands this specific syntax as a Software Heritage fallback URL: https://swhid.opam.ocaml.org/<SWHID>.

url {
  src: "https://faili.ng/url.tar.gz"
  checksum: "sha512=e2146c1d7f53679fd22df66c9061b5ae4f8505b749513eedc67f3c304f297d92e54f5028f40fb5412d32c7d7db92592eacb183128d2b6b81d10ea716b7496eba"
  mirrors: [
    "https//failli.ng/mirror.tar.gz"
    "https://swhid.opam.ocaml.org/swh:1:dir:9f2be900491e1dabfc027848204ae01aa88fc71d"
  ]
}

To add a Software Heritage fallback URL to your package, use the swhid library. Specifically the Compute.directory_identifier_deep function:

Download opam package archive
Extract the archive
Compute SWHID with Compute.directory_identifier_deep. You can use this oneliner in the directory:

ocaml -e '#use "topfind";; #require "digestif.ocaml";; #require "swhid";; Swhid_core.Object.pp Format.std_formatter (Result.get_ok (Swhid.Compute.directory_identifier_deep "."))'

Special thanks to @zapashcanon for collaborating on this feature.

Formula (Experimental)

It is now possible to leverage the full expressivity of package dependency formulas from the command line during switch creation and package operations.

It is possible to create a switch using a formula. For example, with ocaml-variant or ocaml-system, excluding ocaml-base-compiler:

opam switch create ocaml --formula '"ocaml-variants" {>= "4.14.1"} | "ocaml-system"'

This syntax is brought to install commands. For example, while installing a package, let's say genet, you can specify that you want to install either conf-mariadb & mariadb or conf-postgresql:

opam install genet --formula '["mysql" ("conf-mariadb" & "mariadb" | "conf-postgresql")]'

New Options

Here are several of new options (possibly scripts breaking changes are marked with ✘):

opam pin --current to fix a package to its current state (disabling pending reinstallations or removals from the repository). The installed package will be pinned with the opam file that is stored in opam internal state, the one that is currently installed.
opam pin remove --all to remove all the pinned packages from a switch.
opam pin remove pkg.version now removes the pins on pinned pkg.version.
opam exec --no-switch to remove opam environment from launched command.

$ export FOOVAR=env
$ opam show foo --field setenv
FOOVAR = "package"
$ opam exec  -- env | grep "OPAM_SWITCH\|FOO"
FOOVAR=package
OPAM_SWITCH_PREFIX=~/.opam/env
$ opam exec --no-switch -- env | grep "OPAM_SWITCH\|FOO"
FOOVAR=env

opam source --no-switch to allow downloading package sources without having an installed switch (instead of failing).
opam clean --untracked to remove untracked files interactively remaining from previous packages removal.
opam switch -, inspired from git switch -, that goes back to the previously selected global switch.
opam admin add-constraint <cst> --packages pkg1,pkg2,pkg3 to select a subset of packages to apply constraints.
✘ Change --base into --invariant. opam switch compiler column now contains installed packages that verifies invariant formula, and empty synopsis shows switch invariant.

$ opam switch create inv --formula '["ocaml" {>= "4.14.1"} "dune"]'
$ opam switch invariant
["ocaml" {>= "4.14.1"} "dune"]
$ opam list --invariant
# Packages matching: invariant
# Name # Installed # Synopsis
dune   3.8.2       Fast, portable, and opinionated build system
ocaml  5.0.0       The OCaml compiler (virtual package)
$ opam switch list
#  switch   compiler                                            description
→  inv      ocaml-base-compiler.5.0.0,ocaml-options-vanilla.1   ocaml >= 4.14.1 & dune

Try It!

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

The upgrade instructions are unchanged:

From binaries: run

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

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

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

Then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

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

OCaml 5.1.0 - First Beta

04 Jul 2023

ocaml

After two alpha releases, the release of OCaml 5.1.0 is drawing near. We have thus released a first beta version of OCaml 5.1.0 to help you update your softwares and libraries ahead of the release (see below for the installation instructions). Compared to the last alpha release, this beta contains two subtle internal runtime fixes and one Windows fix. Overall, the opam ecosystem looks in a good shape for the first beta release.

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

Nearly all core development tools support OCaml 5.1.0, and you can follow the last remaining wrinkles on the opam readiness for 5.1.0 meta-issue.

Currently, the release is planned for the end of July or the beginning of August.

If you are interested in full list of features and bug fixes of the new OCaml version, the updated change log for OCaml 5.1.0 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 5.1.0~beta1

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

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.5.1.0~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 5.1.0~beta1+flambda+nffa ocaml-variants.5.1.0~beta1+options ocaml-option-flambda ocaml-option-no-flat-float-array

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

See full changelog

Runtime System Bugfix

#12037: Fix some data races by using volatile when necessary (Fabrice Buoro and Olivier Nicole, review by Guillaume Munch-Maccagnoni, Gabriel Scherer and Luc Maranget)
#12253, #12342: Fix infinite loop in signal handling. (Guillaume Munch-Maccagnoni, report by Thomas Leonard, review by KC Sivaramakrishnan and Sadiq Jaffer)

Windows Bugfix

#12184, #12320: Sys.rename Windows fixes on directory corner cases. (Jan Midtgaard, review by Anil Madhavapeddy)

Dune 3.9.0

30 Jun 2023

dune platform

The Dune team is thrilled to announce the release of Dune 3.9.0. This version ships with a host of new features and improvements, including:

New dune show Command: This command enables you to display various pieces of information. For instance, you can use dune show pp to display the preprocessed output of a file or dune show aliases [DIR] to list the aliases available in DIR. Read more about the command on its manpage using dune show --help.
Improved Dialect Support: We have rolled out several fixes related to dialect support. These changes make it easier to work with Dream's .eml files.
Introduction of (build_if) Toggle in (test) Stanza: This new field facilitates the packaging of non-portable tests and benchmarks. If you have tests that don't build on a specific platform, you can now tell Dune not to build them on other Platforms with the build_if field.

Enjoy the new features and improvements incorporated into this version!

See full changelog

Added

Include the time it takes to read/write state files when --trace-file is enabled (#7960, @rgrinberg)
Include source tree scans in the traces produced by --trace-file (#7937, @rgrinberg)
Add --all option to dune rpc status to show all Dune RPC servers running. (#8011, fix #7902, @Alizter)
Add additional metadata to the traces provided by --trace-file whenever --trace-extended is passed (#7778, @rleshchinskiy)
$ dune describe is now a command group, so arguments to subcommands must be passed after subcommand itself. (#7919, @Alizter)
Add dune show command group which is an alias of dune describe. (#7946, @Alizter)
Add dune show env command and make dune printenv an alias of it. (#7985, @Alizter)
Add commands dune show targets and dune show aliases that display all the available targets and aliases in a given directory respectively. (#7770, grants #265, @Alizter)
Extensions used in (dialect) can contain periods (e.g., cppo.ml). (#7782, fixes #7777, @nojb)
The interface and implementation fields of a (dialect) are now optional (#7757, @gpetiot)
Add (build_if) to the (test) stanza. When it evaluates to false, the executable is not built. (#7899, fixes #6938, @emillon)
Allow (include_subdirs qualified) to be used when libraries define a (modules ...) field (#7797, fixes #7597, @anmonteiro)
Allow multiple globs in library's (stdlib (internal_modules ..)) (@anmonteiro, #7878)

Changed

Do not rerun OCaml syntax files on every iteration of the watch mode. This is too memory consuming. (#7894, fix #6900, @rgrinberg)
Attach melange rules to the default alias (#7926, @haochenx)
Compute digests and manage sandboxes in background threads (#7947, @rgrinberg)

Fixed

Validate file extension for $ dune ocaml top-module. (#8005, fixes #8004, @3Rafal)
Cinaps: The promotion rules for cinaps would only offer one file at a time no matter how many promotions were available. Now we offer all the promotions at once (#7901, @rgrinberg)
Add necessary parentheses in generated opam constraints (#7682, fixes #3431, @Lucccyo)

Removed

Remove some compatibility code for old version of dune that generated .merlin files. Now dune will never remove .merlin files automatically (#7562)
In opam constraints, reject (and) and (or) with no arguments at parse time (#7730, @emillon)

OCaml Infrastructure: Upgrading to Debian 12 for OCaml docker images

28 Jun 2023

infrastructure

The OCaml infrastructure team is going to move to Debian 12 as the main distribution from Debian 11. We will continue to provide Debian 11 and 10 images while they are supported, dropping Debian 10 when it reaches end of life in 2024-06-30. In addition to these changes we are deprecating Ubuntu 18.04, Alpine 3.16/17, OL7, OpenSuse 15.2 distributions as the have reached end of life. We strongly recommend updating to a newer version if you are still using them.

Please get in touch on https://github.com/ocaml/infrastructure/issues if you have questions or requests for additional support.

Changes

OCaml Debian images upgraded to Debian 12 (ocaml-dockerfile#172, @MisterDA)
Deprecation of Ubuntu 18.04, Alpine 3.16 and 3.17, OracleLinux 7, OpenSUSE 15.2 images (ocaml-dockerfile#176, @avsm)
Deprecate Ubuntu 18.04, Alpine 3.16/17, OL7, OpenSuse 15.2 for OCaml-CI (ocaml-ci#832, @tmcgilchrist)
Deprecate Ubuntu 18.04, Alpine 3.16/17, OL7, OpenSuse 15.2 for opam-repo-ci (opam-repo-ci#226, @tmcgilchrist)
Deprecate Ubuntu 18.04, Alpine 3.16/17, OL7, OpenSuse 15.2 for docker-base-images (docker-base-images#237, @tmcgilchrist)

Dune 3.8.3

28 Jun 2023

dune platform

This point release fixes two important issues on Windows and Linux.

See full changelog

Fix deadlock on Windows (dune#8044, @nojb)
When using sendfile to copy files on Linux, fall back to the portable version if it fails at runtime for some reason (NFS, etc). (dune#8049, fixes dune#8041, @emillon)

Dune-release 2.0.0

24 Jun 2023

dune-release platform

We're excited to announce the release of Dune-release 2.0.0!

This release brings support for putting your .opam files in a opam/ directory. If your project contains dozens of packages, you'll be able to generate them into the opam/ folder starting with Dune 3.8 using (opam_file_location inside_opam_directory) in your dune-project.

Another notable change is the removal of delegates. Users of dune-release who want to publish their packages to another platform than GitHub can now use the dune-release delegate-info and use the output to build their own publication workflows.

See full changelog

Added

Adopt the OCaml Code of Conduct (#473, @rikusilvola)
Added support for projects that have their OPAM files in the opam/ subdirectory. (#466, @Leonidas-from-XIV)

Changed

Running dune-release check now attempts to discover and parse the change log, and a new flag --skip-change-log disables this behaviour. (#458, @gridbugs)
List the main package and amount of subpackages when creating the PR to avoid very long package lists in PRs (#465, @emillon)

Fixed

Avoid collision between branch and tag name. Tag detection got confused when branch was named the same as tag. Now it searches only for tag refs, instead of all refs. (#452, @3Rafal)
Fix project name detection from dune-project. The parser could get confused when opam file generation is used. Now it only considers the first (name X) in the file. (#445, @emillon)

Removed

Remove support for delegates. Previous users of this feature should now use dune-release delegate-info and wrap dune-release calls in a script. See #188 for details. (#428, @NathanReb)
Removed support for the OPAM 1.2.2 client. This means dune-release expects the opam binary to be version 2.0 at least. (#406, #411, @Leonidas-from-XIV)

OCaml-LSP 1.16.2

23 Jun 2023

ocaml-lsp platform

We've released OCaml LSP 1.16.2 with a fix that was introduced in 1.16.1 that prevented users from using preprocessor such as CPPO.

See full changelog

Fixes

Fix file permissions used when specifying output files of pp and ppx. (ocaml-lsp#1153)

OCaml-LSP 1.16.1

21 Jun 2023

ocaml-lsp platform

We're thrilled to announce the release of OCaml LSP 1.16.1! 🎉

This release comes with new "Extract local" and "Extract function" code actions to easily refactor your code.

We've also disabled code lenses by default following user feedback. You can follow the discussion on GitHub.

This release is also the first OCaml LSP release to use upstream Merlin. Among other things, this means that it is compatible with all the OCaml versions supported by Merlin: currently OCaml 4.14 and 5.0.0.

We're also releasing numerous bug fixes, including:

A fix to the integration with Dune RPC on Windows, which, alongside Dune 3.9.0, makes OCaml LSP report Dune errors to the editors with Dune watch mode enabled.
Minor improvements to the Odoc <-> Markdown conversion to return better function documentation on the editor.

And much more! Read the full changelog for a complete list of improvements and bug fixes.

See full changelog

Features

Add "Remove type annotation" code action. (#1039)
Support settings through didChangeConfiguration notification (#1103)
Add "Extract local" and "Extract function" code actions. (#870)
Depend directly on merlin-lib 4.9 (#1070)

Fixes

Support building with OCaml 5.0 and 5.1 (#1150)
Disable code lens by default. The support can be re-enabled by explicitly setting it in the configuration. (#1134)
Fix initilization of ocamlformat-rpc in some edge cases when ocamlformat is initialized concurrently (#1132)
Kill unnecessary $ dune ocaml-merlin with SIGTERM rather than SIGKILL (#1124)
Refactor comment parsing to use odoc-parser and cmarkit instead of octavius and omd (#1088)

This allows users who migrated to omd 2.X to install ocaml-lsp-server in the same opam switch.

We also slightly improved markdown generation support and fixed a couple in the generation of inline heading and module types.
Allow opening documents that were already open. This is a workaround for neovim's lsp client (#1067)
Disable type annotation for functions (#1054)
Respect codeActionLiteralSupport capability (#1046)
Fix a document syncing issue when utf-16 is the position encoding (#1004)
Disable "Type-annotate" action for code that is already annotated. (#1037, fixes #1036)
Fix semantic highlighting of long identifiers when using preprocessors (#1049, fixes #1034)
Fix the type of DocumentSelector in cram document registration (#1068)
Accept the --clientProcessId command line argument. (#1074)
Accept --port as a synonym for --socket. (#1075)
Fix connecting to dune rpc on Windows. (#1080)

Ppxlib 0.30.0

20 Jun 2023

ppxlib

We're excited to announce the release of Ppxlib 0.30.0! It comes with support for OCaml 5.1, various enhancements, and bug fixes.

For PPX writing, Ast_pattern now offers additional utility functions, while metaquot benefits from improved error reporting.

PPX usage sees better compatibility with OCaml trunk, thanks to the Driver's improved Parsetree version recognition. This allows for compatibility with both trunk and stable OCaml versions concurrently.

Finally, this release enhances Ppxlib's compatibility with ReScript, introducing "ns" and "res" as reserved namespaces.

See full changelog

Adopt the OCaml Code of Conduct on the repo (ocaml-ppx/ppxlib#426, @pitag-ha)
Clean up misleading attribute hints when declared for proper context. (ocaml-ppx/ppxlib#425, @ceastlund)
Ast_pattern now has ebool, pbool helper, and a new map.(ocaml-ppx/ppxlib#402, @Burnleydev1)
Multiple errors are now reported in metaquot. (ocaml-ppx/ppxlib#397, @Burnleydev1)
Add Attribute.declare_with_attr_loc (ocaml-ppx/ppxlib#396, @dvulakh)
Add "ns" and "res" as reserved namespaces(ocaml-ppx/ppxlib#388, @davesnx)
Make Quoter's let binding non-recursive (ocaml-ppx/ppxlib#401, @sim642)
Fix failure of 'lift_map_with_context' in traverse by compile-time evaluation of 'fst' and 'snd' (ocaml-ppx/ppxlib#390, @smuenzel)
Driver: Bias the mapping from Parsetree magic numbers to Parsetree versions towards the current version, as it is usually the common case and it helps when magic numbers are ambiguous (such as on development versions) (ocaml-ppx/ppxlib#409, @shym)
Remove unnecessary test dependencies towards base and stdio (ocaml-ppx/ppxlib#421, @kit-ty-kate)
Update description to reflect that ppxlib contains more than a library (Update the opam description ocaml-ppx/ppxlib#422, @pitag-ha)
Add support for OCaml 5.1, excluding OCaml 5.1.0~alpha1 (ocaml-ppx/ppxlib#428, @shym, @Octachron , @pitag-ha, @panglesd)
Driver: Fix -locations-check option for coercions with ground (ocaml-ppx/ppxlib#428, @Octachron)

Dune 3.8.2

19 Jun 2023

dune platform

We've released Dune 3.8.2 with a few bug fixes.

See full changelog

Switch back to threaded console for all systems; fix unresponsive console on Windows (dune#7906, @nojb)
Respect -p / --only-packages for melange.emit artifacts (dune#7849, @anmonteiro)
Fix scanning of Coq installed files (@ejgallego, reported by @palmskog, dune#7895 , fixes dune#7893)
Fix RPC buffer corruption issues due to multi threading. This issue was only reproducible with large RPC payloads (dune#7418)
Fix printing errors from excerpts whenever character offsets span multiple lines (dune#7950, fixes dune#7905, @rgrinberg)

OCaml Infrastructure: Relocation of opam.ci.ocaml.org and ocaml.ci.dev

15 Jun 2023

infrastructure

The server toxis where Opam-Repo-CI and OCaml-CI were deployed suffered hardware difficulties yesterday, resulting in BTRFS filesystem corruption and memory issues. These issues are tracked on ocaml/infrastructure#51. Services were restored temporarily using a spare spinning disk, but we continued to see ECC memory issues.

All services have now been redeployed on new ARM64 hardware. We retained the databases for Prometheus, OCaml-CI and Opam-Repo-CI, but unfortunately, older job logs have been lost.

The external URLs for these services are unchanged.

OCaml Infrastructure: Grafana Dashboard Changes

09 Jun 2023

infrastructure

The Grafana dashboards at status.ci3.ocamllabs.io and status.ci.ocamllabs.io have been merged into a single dashboard at status.ci.ocamllabs.io. HTTP redirects are in place for the old addresses.

Dune 3.8.1

06 Jun 2023

dune platform

We've just released a patch version of Dune to fix regressions introduced in Dune 3.8.0.

In particular, we've reverted some cross-compilation improvements that caused build failures when using ppx_runtime_libraries and we'll revisit them in a future version of Dune.

See full changelog

Fix a crash when using a version of Coq < 8.13 due to the native compiler config variable being missing. We now explicitly default to (mode vo) for these older versions of Coq. (dune#7847, fixes dune#7846, @Alizter)
Duplicate installed Coq theories are now allowed with the first appearing in COQPATH being preferred. This is inline with Coq's loadpath semantics. This fixes an issue with install layouts based on COQPATH such as those found in nixpkgs. (dune#7790, @Alizter)
Revert dune#7415 and dune#7450 (Resolve ppx_runtime_libraries in the target context when cross compiling) (dune#7887, fixes dune#7875, @emillon)

OCaml 5.1.0 - Second Alpha

01 Jun 2023

ocaml

With the progress of the ongoing stabilisation effort for OCaml 5.1.0, I am happy to announce a second alpha release for OCaml 5.1.0.

This second alpha release contains many noteworthy fixes:

a long-awaited GC fix
a Windows ABI fix

as announced in the first alpha but also

a compiler-libs (parsetree) fix
a type system compatibility enhancement change
a restored backed for s390x/IBM Z

The full list of changes since the first alpha is available below.

Once most major OCaml tools are updated to the last compiler-libs changes, we will switch to beta releases. Hopefully, this will happen in the upcoming weeks. The progress on stabilising the ecosystem is tracked on the opam readiness for 5.1.0 meta-issue.

Currently, the release is still planned for around July.

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 5.1.0 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 5.1.0~alpha2

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

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.5.1.0~alpha2+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 5.1.0~alpha2+flambda+nffa ocaml-variants.5.1.0~alpha2+options ocaml-option-flambda ocaml-option-no-flat-float-array

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

See full changelog

Runtime System

#11589, #11903: Modify the GC pacing code to make sure the GC keeps up with allocations in the presence of idle domains. (Damien Doligez and Stephen Dolan, report by Florian Angeletti, review by KC Sivaramakrishnan and Sadiq Jaffer)

(breaking change) #11865, #11868, #11876: Clarify that the operations of a custom block must never access the OCaml runtime. The previous documentation only mentioned the main illicit usages. In particular, since OCaml 5.0, it is no longer safe to call caml_remove_global_root or caml_remove_generational_global_root from within the C finalizer of a custom block, or within the finalization function passed to caml_alloc_final. As a workaround, such a finalization operation can be registered with Gc.finalize instead, which guarantees to run the finalizer at a safe point. (Report by Timothy Bourke, discussion by Yotam Barnoy, Timothy Bourke, Sadiq Jaffer, Xavier Leroy, Guillaume Munch-Maccagnoni, and Gabriel Scherer)

#11827, +#12249: Restore prefetching for GC marking (Fabrice Buoro and Stephen Dolan, review by Gabriel Scherer and Sadiq Jaffer)

#12131: Simplify implementation of weak hash sets, fixing a performance regression. (Nick Barnes, review by François Bobot, Alain Frisch and Damien Doligez).
#12231: Support MinGW-w64 11.0 winpthreads library, where the macro to set up to get flexdll working changed (David Allsopp and Samuel Hym, light review by Xavier Leroy)

Type System

(breaking change) #12189, #12211: anonymous row variables in explicitly polymorphic type annotation, e.g. 'a. [< X of 'a ] -> 'a, are now implicitly universally quantified (in other words, the example above is now read as 'a 'r. ([< X of 'a ] as 'r) -> 'a). (Florian Angeletti and Gabriel Scherer, review by Jacques Garrigue)

Code Generation And Optimizations

#11712, #12258, #12261: s390x / IBM Z multicore support: OCaml & C stack separation; dynamic stack size checks; fiber and effects support. (Aleksei Nikiforov, with help from Vincent Laviron and Xavier Leroy, additional suggestions by Luc Maranget, review by the same and KC Sivaramakrishnan)

Internal/compiler-libs Changes

#12119, +#12188, +#12191: mirror type constraints on value binding in the parsetree: the constraint typ in let pat : typ = exp is now directly stored in the value binding node in the parsetree. (Florian Angeletti, review by Richard Eisenberg)

Bug Fixes

#11846: Mark rbx as destroyed at C call for Win64 (mingw-w64 and Cygwin64). Reserve the shadow store for the ABI in the c_stack_link struct instead of explictly when calling C functions. This simultaneously reduces the number of stack pointer manipulations and also fixes a bug when calling noalloc functions where the shadow store was not being reserved. (David Allsopp, report by Vesa Karvonen, review by Xavier Leroy and KC Sivaramakrishnan)
#12170: fix pthread_geaffinity_np configure check for android (David Allsopp, review by Sébastien Hinderer)
#12252: Fix shared library build error on RISC-V. (Edwin Török, review by Nicolás Ojeda Bär and Xavier Leroy)
#12255, #12256: Handle large signal numbers correctly (Nick Barnes, review by David Allsopp).
#12277: ARM64, fix a potential assembler error for very large functions by emitting stack reallocation code before the body of the function. (Xavier Leroy, review by KC Sivaramakrishnan)

opam 2.1.5

31 May 2023

opam platform

Feedback on this post is welcomed on Discuss!

We are pleased to announce the patch release of opam 2.1.5.

This opam release consists of backported bug & security fixes:

Security issue: fix opam installing packages without checking their checksum when the local cache is corrupted in some case (#5538), you can find more information there.
Variables are now expanded in build-env (as for setenv) (#5352)
Correctly handle empty environment variable additions (#5350)
Skip empty environment variable additions (#5350)
Fix passing archive-mirrors field from init config file to config (#5315)
git, hg: Use the full SHA1 revision instead of just the 8 first characters (#5342)

Opam installation instructions (unchanged):

From binaries: run
```
bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.1.5"
```
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.
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)
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.

See full changelog

[BUG] Variables are now expanded in build-env (as for setenv) [#5352 @dra27]
Correctly handle empty environment variable additions [#5350 @dra27]
Skip empty environment variable additions [#5350 @dra27]
[BUG] Fix passing archive-mirrors field from init config file to config [#5315 @hannesm]
git, hg: Use the full SHA1 revision instead of just the 8 first characters [#5342 @reynir]
[BUG] Fix opam installing packages without checking their checksum when the local cache is corrupted in some case [#5538 @kit-ty-kate]

Merlin 4.9

31 May 2023

merlin platform

We are pleased to announce the release of Merlin 4.9 for OCaml 4.14.1 and 5.0.

This maintenance release brings multiple bug fixes and improvements. In particular we identified and patched an important memory consumption issue that could greatly affect Merlin’s performance in heavily functorized projects.

See full changelog

merlin binary
- Allow monadic IO in dot protocol (#1581)
- Add a scope option to the occurrences command in preparation for the upcoming project-wide-occurrences feature (#1596)
- Construct bool-typed holes as false instead of true in the construct command, for consistency (#1599).
- Add a hook to configure system command for spawning ppxes when Merlin is used as a library. (#1585)
- Implement an all-or-nothing cache for the PPX phase (#1584)
- Cleanup functors caches when backtracking, to avoid memory leaks (#1609, fixes #1529 and ocaml-lsp#1032)
- Fix construct results ordering for sum types sand poly variants (#1603)
- Fix object method completion not working (#1606, fixes #1575)
- Improve context detection for package types (#1608, fixes #1607)
- Fix incorrect locations for string literals (#1574)
- Fixed an issue that caused errors to erroneously alert about missing cmi files (#1577)
- Prevent destruct from crashing on closed variant types (#1602, fixes #1601)
- Improve longident parsing (#1612, fixes #945)
editor modes
- emacs: call the user's configured completion UI in merlin-construct (#1598)
test suite
- Add missing dependency to a test using ppxlib (#1583)
- Add tests for the new PPX phase cache (#1584)
- Add and update tests for construct ordering (#1603)

Dune 3.8.0

31 May 2023

dune platform

The dune team is pleased to announce the release of Dune 3.8.0.

It is now available in opam-repository. As usual, it should always be safe to upgrade your dune package: new features and deprecations are only available if you upgrade the language version in your dune-project files.

🌟 Spotlight Features

Dune concurrent action

Dune 3.8.0 introduced the new concurrent action. You can now use it instead of the progn action to execute actions concurrently.

For instance:

(rule
(action
  (concurrent
  (write-file A "I am file A.\n")
  (write-file B "I am certainly file B.\n")
  (write-file C "I am most certainly file C.\n"))))

will write to files A, B and C concurrently.

Support for .mld files

In Dune 3.7.0, we introduced version 0.3 of the mdx stanza, which came with support for .mld files.

In Dune 3.8.0, .mld files are now supported by default with version 0.4 of the mdx stanza!

Have a look at this diff to see how to migrate your code to the new stanza version.

See full changelog

Added

Introduce mdx stanza 0.4 requiring mdx >= 2.3.0 which updates the default list of files to include *.mld files (#7582, @Leonidas-from-XIV)
Allow (stdlib ...) to be used with (wrapped false) in library stanzas (#7139, @anmonteiro).
Allow the main module of a library with (stdlib ...) to depend on other libraries (#7154, @anmonteiro).
Support (link_flags ...) in (cinaps ...) stanza. (#7423, fixes #7416, @nojb)
Allow (package ...) in any position within (rule ...) stanza (#7445, @Leonidas-from-XIV)
Added a new user action (concurrent ) which is like (progn ) but runs the actions concurrently. (#6933, @Alizter)
Accept the Ordered Set Language for the modes field in library stanzas (#6611, @anmonteiro).
Allow parallel execution of inline tests partitions (#7012, @hhugo)
Add the --display-separate-messages flag to separate the error messages produced by commands with a blank line. (#6823, fixes #6158, @esope)
Add --watch-exclusions to Dune build options (#7216, @jonahbeckford)
Adds support for loading plugins in toplevels (#6082, fixes #6081, @ivg, @richardlford)
Introduce a public_headers field on libraries. This field is like install_c_headers, but it allows to choose the extension and choose the paths for the installed headers. (#7512, @rgrinberg)
Dune can now detect Coq theories from outside the workspace. This allows for composition with installed theories (not necessarily installed with Dune). (#7047, @Alizter, @ejgallego)
Added a --no-build option to dune coq top for avoiding rebuilds (#7380, fixes #7355, @Alizter)
Add a coqdoc_flags field to the coq.theory stanza allowing the user to pass extra arguments to coqdoc. (#7676, fixes #7954 @Alizter)
Preliminary support for Coq compiled intefaces (.vos files) enabled via (mode vos) in coq.theory stanzas. This can be used in combination with dune coq top to obtain fast re-building of dependencies (with no checking of proofs) prior to stepping into a file. (#7406, @rlepigre)
Read pkg-config arguments from the PKG_CONFIG_ARGN environment variable (#1492, #7734, @anmonteiro)
Use $PKG_CONFIG, when set, to find the pkg-config binary (#7469, fixes #2572, @anmonteiro)

Changed

Bootstrap: remove reliance on shell. Previously, we'd use the shell to get the number of processors. (#7274, @rgrinberg)
Non-user proccesses such as version control or config checking are now run silently. (#6994, fixes #4066, @Alizter)
Bytecode executables built for JSOO are linked with -noautolink and no longer depend on the shared stubs of their dependent libraries (#7156, @nojb)
Always include opam files in the generated .install file. Previously, it would not be included whenever (generate_opam_files true) was set and the .install file wasn't yet generated. (#7547, @rgrinberg)

Deprecated

Modules that were declared in (modules_without_implementation), (private_modules) or (virtual_modules) but not declared in (modules) will cause Dune to emit a warning which will become an error in 3.9. (#7608, fixes #7026, @Alizter)
Coq language versions less 0.8 are deprecated, and will be removed in an upcoming Dune version. All users are required to migrate to (coq lang 0.8) which provides the right semantics for theories that have been globally installed, such as those coming from opam (@ejgallego, @Alizter)

Fixed

Find pps dependencies in the host context when cross-compiling, (#7415, fixes #4156, @anmonteiro)
Fix plugin loading with findlib. The functionality was broken in 3.7.0. (#7556, @anmonteiro)
Load the host context findlib.conf when cross-compiling (#7428, fixes #1701, @rgrinberg, @anmonteiro)
Allow overriding the ocaml binary with findlib configuration (#7648, @rgrinberg)
Resolve ppx_runtime_libraries in the target context when cross compiling (#7450, fixes #2794, @anmonteiro)
Fix dune install when cross compiling (#7410, fixes #6191, @anmonteiro, @rizo)
Fix string quoting in the json file written by --trace-file (#7773, @rleshchinskiy)
Correctly set MANPATH in dune exec. Previously, we would use the bin/ directory of the context. (#7655, @rgrinberg)
merlin: ignore instrumentation settings for preprocessing. (#7606, fixes #7465, @Alizter)
When a rule's action is interrupted, delete any leftover directory targets. This is consistent with how we treat file targets. (#7564, @rgrinberg)
Fix dune crashing on MacOS in watch mode whenever $PATH contains $PWD (#7441, fixes #6907, @rgrinberg)
Dune in watch mode no longer builds concurrent rules in serial (#7395 @rgrinberg, @jchavarri)
dune coq top now correctly respects the project root when called from a subdirectory. However, absolute filenames passed to dune coq top are no longer supported (due to being buggy) (#7357, fixes #7344, @rlepigre and @Alizter)
RPC: Ignore SIGPIPE when clients suddenly disconnect (#7299, #7319, fixes #6879, @rgrinberg)
Always clean up the UI on exit. (#7271, fixes #7142 @rgrinberg)
Bootstrap: correctly detect the number of processors by allowing nproc to be looked up in $PATH (#7272, @Alizter)
Speed up file copying on macos by using clonefile when available (@rgrinberg, #7210)
Support commands that output 8-bit and 24-bit colors in the terminal (#7188, @Alizter)
Speed up rule generation for libraries and executables with many modules (#7187, @jchavarri)
Do not re-render UI on every frame if the UI doesn't change (#7186, fix #7184, @rgrinberg)
Make coq_db creation in scope lazy (@ejgallego, #7133)
dune install now respects --display quiet mode (#7116, fixes #4573, fixes #7106, @Alizter)
Stub shared libraries (dllXXX_stubs.so) in Dune-installed libraries could not be used as dependencies of libraries in the workspace (eg when compiling to bytecode and/or Javascript). This is now fixed. (#7151, @nojb)
Fix regression where Merlin was unable to handle filenames with uppercase letters under Windows. (#7577, @nojb)
On nix+macos, pass -f to the codesign hook to avoid errors when the binary is already signed (#7183, fixes #6265, @greedy)
Fix bug where RPC clients built with dune-rpc-lwt would crash when closing their connection to the server (#7581, @gridbugs)
Fix RPC server on Windows (used for OCaml-LSP). (#7666, @nojb)

OCaml Infrastructure: Temporary relocation of opam.ci.ocaml.org

05 May 2023

infrastructure

Due to operational difficulties, opam.ci.ocaml.org has temporarily moved to toxis.caelum.ci.dev. An HTTP redirect is in place. Please do not update your bookmarks.

This issue is being tracked on GitHub ocurrent/opam-repo-ci#220.

OCaml Infrastructure: check.ocamllabs.io moved to check.ci.ocaml.org

26 Apr 2023

infrastructure

check.ocamllabs.io has moved to check.ci.ocaml.org. Furthermore, HTTP connections are now upgraded to HTTPS.

There is an HTTP 301 permanent redirect in place for the old address.

OCaml Infrastructure: Updated Linux Distros and OCaml versions

25 Apr 2023

infrastructure

New Ubuntu 23.04 and Fedora 38 distributions have been added to docker base image builder. Following their respective releases:

Ubuntu 23.04 was released 20 April 2023
Fedora 38 was released 18 April 2023 These images started building from Apr 25th 2023 and have been pushed to https://hub.docker.com/r/ocaml/opam with a full range of OCaml versions and variants. As always the status of the images can be viewed on images.ci.ocaml.org.

Alongside the Linux updates base images containing OCaml 5.1 have also been published for supported Linux platforms. Following the OCaml 5.1 Alpha release announcement on discuss.ocaml.org. Enjoy and please report any issues on ocurrent/docker-base-images/issues.

Utop 2.12.1

24 Apr 2023

utop platform

Following the release of UTop 2.12.0 a few days ago, we released UTop 2.12.1, a patch release that fixes a regression with unit qualification.

This release also includes an implementation of completion-at-point for Emacs.

See full changelog

Fix regression with unit qualification when a Unit module is in scope with no () constructor (fix regression with unit qualification ocaml-community/utop#429, fixes regression with qualifying () ocaml-community/utop#428, @emillon)
emacs: add completion-at-point implementation (Add completion-at-point implementation ocaml-community/utop#261 ocaml-community/utop#406, fixes utop emacs completion-at-point-functions support? ocaml-community/utop#261, @j-shilling)

Utop 2.12.0

17 Apr 2023

utop platform

UTop 2.12.0 is out with support for the upcoming release of OCaml 5.1!

This release also fixes an issue that prevented users to redefine the () constructor. You can now safely run type t = () of unit and continue using your top-level session.

See full changelog

Add support for OCaml 5.1 (#421, @emillon)
Mark prompt_continue, prompt_comment, smart_accept, new_prompt_hooks, at_new_prompt as deprecated (they have been documented as such since 2012 and most of them are ignored) (#415, @emillon)
Qualify () constructor in generated expressions. (#418, fixes #417, @emillon)

Mdx 2.3.0

17 Apr 2023

mdx platform

We're pleased to announce the release of Mdx 2.3.0!

This release comes with support for mld files and changes the parser used by the toplevel, which allows Camlp5's parser to be used with MDX.

🌟 Spotlight Feature

Starting in MDX 2.3.0, you can now execute code blocks in your .mld files! 🎉

As a reminder, .mld files are text files similar to Markdown, but instead of using the Markdown markup language, they use the Ocamldoc markdown language - as is used in .mli files. .mld are typically used to write manuals with odoc.

To run mdx on .mld files, start by enabling mdx in your dune-project:

(using mdx 0.3)

Then list your .mld files in the mdx stanza in your dune:

(mdx
 (files index.mld))

Now if you put a code block in index.mld, it will be executed when running dune test and if dune will suggest to promote the output. For instance, if you run dune test with this index.mld:

Here's an example code block in a [.mld] file:

{[
  # List.map (fun x -> x * x) [(1 + 9); 2; 3; 4];;
]}

dune test will return:

diff --git a/_build/default/index.mld b/_build/default/.mdx/index.mld.corrected
index 337b042..c29bb63 100644
--- a/_build/default/index.mld
+++ b/_build/default/.mdx/index.mld.corrected
@@ -2,5 +2,6 @@ Here's an example code block in a [.mld] file:
 
 {[
   # List.map (fun x -> x * x) [(1 + 9); 2; 3; 4];;
+  - : int list = [100; 4; 9; 16]
 ]}

You can run dune promote to accept the change.

You can see a complete demo of this here.

Now you can keep the code blocks in your manual up-to-date even when your API changes!

See full changelog

Added

Added support for mld files (#423, @jonludlam)

Changed

Switch to using the parser that toplevel uses (found in a mutable ref, instead of always the official OCaml parser). This allows Camlp5's parser to be used with MDX. (#417, @chetmurthy)

OCaml 5.1.0 - First Alpha

14 Apr 2023

ocaml

Four months after the release of OCaml 5.0.0, the set of new features for the future version 5.1.0 of OCaml has been frozen. We are thus happy to announce the first alpha release for OCaml 5.1.0.

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). The progresses on stabilising the ecosystem are tracked on the opam readiness for 5.1.0 meta-issue.

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

Note that this early alpha version is missing two important fixes for the garbage collector and Windows support. Those fixes will be available before the beta. The full release is expected in July.

If you are interested in the ongoing list of new features and bug fixes, the updated change log for OCaml 5.1.0 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 5.1.0~alpha1

For previous version of opam, the switch creation command line is slightly more verbose:

opam update
opam switch create 5.1.0~alpha1 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

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

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.5.1.0~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 5.1.0~alpha1+flambda+nffa ocaml-variants.5.1.0~alpha1+options ocaml-option-flambda ocaml-option-no-flat-float-array

The command line above is slightly more complicated for opam version anterior to 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.5.1.0~alpha1+options,<option_list> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

In both cases, all available options can be listed with opam search ocaml-option.

OCaml Infrastructure: Maintenance Operations

06 Apr 2023

infrastructure

Due to maintenance operations on Tuesday 11th April between 7:30am and 11:00am (UTC+1), the build system will be running at approximately 50% capacity. You may experience some build delays in Opam Repo CI and OCaml CI.

Thank you for your patience and understanding during this time.

Dune 3.7.1

05 Apr 2023

dune platform

We are excited to announce the release of Dune 3.7.1, which brings a few bug fixes from the recent 3.7.0 release:

Resolved watch mode issue for executables on macOS: We have addressed a problem with the recently introduced watch mode for executables that was causing segmentation faults on macOS. Users can now enjoy a stable watch mode without unexpected crashes on macOS.
Fixed "Too many links" error on Windows: We have fixed an issue that caused Dune build failures with a "Too many links" error on Windows when using Dune cache.

... and a few more, you can consult the changelog for a full list of bug fixes.

See full changelog

Fix segfault on MacOS when dune was being shutdown while in watch mode. (#7312, fixes #6151, @gridbugs, @emillon)
Fix preludes not being recorded as dependencies in the (mdx) stanza (#7109, fixes #7077, @emillon).
Pass correct flags when compiling stdlib.ml. (#7241, @emillon)
Handle "Too many links" errors when using Dune cache on Windows. The fix in 3.7.0 for this same issue was not effective due to a typo. (#7472, @nojb)

OCaml Infrastructure: Renaming opam.ci.ocaml.org / opam.ci3.ocamllabs.io

17 Mar 2023

infrastructure

The intention is to retire the ocamllabs.io domain. Therefore any services using the domain will be redirected. From today, the Web UI for Opam Repo CI is available on both opam-ci.ci3.ocamllabs.io and opam.ci.ocaml.org with the service available at both opam-repo-ci.ci3.ocamllabs.io and opam-repo.ci.ocaml.org. In time, the ocamllabs.io sites will issue HTTP 301 permanent redirect messages.

Previously, opam.ci.ocaml.org targetted a web server which issued an HTTP 302 redirect to opam.ci3.ocamllabs.io. This redirection has been removed. opam.ci.ocaml.org points to the actual site.

OCaml Infrastructure: Sunsetting opam-repository-mingw

10 Mar 2023

infrastructure

As previously announced, "opam-repository-mingw" is no longer receiving updates.

We're actively working on getting the Windows compiler packages into ocaml/opam-repository. There are two issues which are taking (me) a little while to finish solving, but more on that further below.

In the gap - of hopefully only a month or so - for this being ready, there's is an issue that new releases are of course not available when opam-repository-mingw is being used with ocaml/setup-ocaml@v2 GitHub actions workflows. I'm hoping here to set out what's happening, and what steps you may need to take to keep your GitHub Actions Windows workflows running smoothly over the next few months.

What's happening right now?

We've updated setup-ocaml to use ocaml-opam/opam-repository-mingw instead of fdopen/opam-repository-mingw (see ocaml/setup-ocaml#651). This clone has been augmented with:

OCaml 4.14.1 packages, in the same style as the 4.14.0 forked packages (the "pre-compiled" package variants exist, but they're not pre-compiled)
Changes to the constraints for existing packages only

If you're using setup-ocaml in its default configuration, you should notice no change except that 4.14.x builds should now use 4.14.1 and the initial build will be a little slower as it builds from sources (GitHub Actions caching will then take over for subsequent runs).

For new releases of packages, it's necessary to add opam-repository to the repositories selections for the switches. It's important that opam-repository is at a lower priority than opam-repository-mingw for existing packages, so it's better to use these lines in your ocaml/setup-ocaml@v2 step than to issue opam repo add --rank=1000 later:

uses: ocaml/setup-ocaml@v2
with:
  opam-repositories: |
    opam-repository-mingw: https://github.com/ocaml-opam/opam-repository-mingw.git#sunset
    default: https://github.com/ocaml/opam-repository.git

What do I do when things are broken?

There's an issue tracker on ocaml-opam/opam-repository-mingw, and this is a very good place to start.

If a version of a package isn't building, there are three possible remedies:

Previous versions of the package may have carried non-upstreamed patches in opam-repository-mingw. opam-repository's policy is not to carry such patches. In this case, the package actually doesn't work on Windows.
- opam-repository should be updated to have os != "win32" added to the available field for the package
- An issue on the package's upstream repo should be opened highlighting the need to upstream patches (or even a pull request with them!)
- The patches in opam-repository-mingw make changes which may not necessarily be accepted/acceptable upstream in their current form, so the issue may be a better starting point than simply taking a patch and opening a pull request for it (for example, the utop package contains patches which may require further work and review)
The package relies on environment changes in "OCaml for Windows". For example, the Zarith package works in "OCaml for Windows" because the compiler packages unconditionally set the CC environment variable. This change is both not particularly desirable change to upstream (it is very confusing, for example, when working on the compiler itself) and also extremely difficult to upstream, so the fix here is instead to change the package's availability with (os != "win32" | os-distribution = "cygwinports") and constrain away OCaml 5 on Windows ("ocaml" {< "5.0" | os != "win32"})
Package constraints on existing packages need updating in ocaml-opam/opam-repository-mingw. For example, the release of ppxlib 0.29 required some existing packages to have upperbounds added.

What about OCaml 5.0.0?

OCaml 5.0.0 was released with support for the mingw-w64 port only, however, there's a quite major bug which wasn't caught by OCaml's testsuite, but is relatively easily triggered by opam packages. I've previously announced how to add OCaml 5 to a workflow. For the time being, the packages for OCaml 5 aren't automatically made available.

What's next?

The ultimate goal is to be using an upstream build of opam.exe with ocaml/opam-repository, just as on Unix. Once opam 2.2 is generally available (we're aiming for an alpha release at the end of March) and the compiler packages in opam-repository support the Windows builds, we will recommend stopping use of opam-repository-mingw completely. The default in setup-ocaml won't change straight away, since that risks breaking existing workflows.

With upstream compiler support, we'll be able to extend some of the existing bulk build support already being done for Linux to Windows and start to close the gap of patches in opam-repository-mingw.

Windows compiler packages

I mentioned earlier the problems with moving the compiler packages into opam-repository, and just for general interest this elaborates on them.

The first issue affects the use of the Visual Studio port ("MSVC") and is a consequence of the somewhat strange way that the C compiler is added to the environment when using the Visual Studio C compiler. "OCaml for Windows" (as well as Diskuv) use a wrapper command (it's ocaml-env in "OCaml for Windows" and with-dkml in Diskuv). Those commands are Windows-specific, which is an issue for upstream opam. There's an alternate way which sets the environment variables in a more opam-like way. Doing it that way, though, requires an improvement to opam's environment handling which is in opam 2.2, otherwise there's an easy risk of "blowing" the environment.

The second issue is selecting the C compiler. On Unix, this is easy with ocaml-base-compiler because there is only one "system" C compiler. Windows has two ports of OCaml, and the configuration requires it to be explicitly selected. That requires input from the user on switch creation for a Windows switch.

"OCaml for Windows" solves this by packaging the Windows compilers with the variant name appended, just as opam-repository used to, so ocaml-variants.4.14.1+mingw64 selects the the mingw-w64 port and ocaml-variants.4.14.1+msvc64 selects the MSVC64 port. The problem, as we already had in opam-repository, is that this adds 4 packages for each release of OCaml in ocaml-variants, and leads to a combinatorial explosion when we start considering flambda and other relevant compiler options.

opam-repository switched to using the ocaml-option- packages to solve the combinatorial explosion which was already present in opam-repository. The demonstration repo for OCaml 5 on Windows is already using an adapted version of this so that ocaml-option-mingw selects the mingw-w64 port (by default 64-bit, with ocaml-option-32bit then selecting the 32-bit port).

This work is all in progress and being tested alongside changes in opam 2.2 to support the depext experience on Windows. The only reason that's not being upstreamed piecemeal is that changes to the compiler packages in opam-repository trigger switch rebuilds all over the world, so we don't want to that until we're sure that the packages are correct. The intention is to do this around the time of the alpha release of opam 2.2, once the work in opam itself has settled down.

Thanks for getting to the end, and happy Windows CI testing!

Discuss this post further on the forums.

OCaml Infrastructure: opam.ocaml.org Moves to Scaleway

09 Mar 2023

infrastructure

Following @avsm post on discuss.ocaml.org, we are pleased to announce that DNS names have now been switched over.

We are moving the opam.ocaml.org 2 servers between hosting providers, and wanted to give everyone clear notice that this happening. Over the next 24-48 hours, if you notice any unexpected changes in the way your opam archives work (for example, in your CI or packaging systems), then please do let us know immediately, either here or in ocaml/infrastructure#19 2.

The reason for the move is to take advantage of Scaleway’s generous sponsorship of ocaml.org, and to use their energy efficient renewable infrastructure 4 for our machines.

This also marks a move to building the opam website via the ocurrent 1 infrastructure, which leads to faster and more reliable updates to the hosted package archives (see here for the service graph and build logs 4). There are also now multiple machines behind the opam.ocaml.org 2 DNS (via round-robin DNS), and this makes it easier for us to publish the archives to a global CDN in the future.

But in the very short term, if something explodes unexpectedly, please do let us know.

OCamlFormat 0.25.1

06 Mar 2023

ocamlformat platform

We are pleased to announce the release of OCamlFormat 0.25.1! This release contains several bug fixes, changes, and new features.

The library is also available through the ocamlformat-lib package on opam. The ocamlformat package only contains the binary.

We would like to thank all contributors for their valuable contributions to this release. Please see the complete changelog for more details.

We hope you enjoy this release and continue to find OCamlFormat a valuable tool for your OCaml projects. You can download ocamlformat.0.25.1 from the opam repository or GitHub.

Thank you for your support and feedback, and please don't hesitate to reach out if you have any questions or issues.

The OCamlFormat team

🌟 Spotlight Feature

New if-then-else and break-cases options

Starting in OCamlFormat 0.25.1, we've also added new values to the if-then-else and break-cases options. Now you can use the vertical value to format these expressions in a more readable and consistent way.

These options are not set by default but you can try them out by customizing your .ocamlformat file as usual.

Here are a few examples:

if-then-else = vertical

-  let epi = if Option.is_some next then fmt "@\n" else fmt_opt epi in
+  let epi =
+    if Option.is_some next then
+      fmt "@\n"
+    else
+      fmt_opt epi
+  in

-    if tree_depth tree > depth then node_depth_truncate_ depth node
-    else (* already short enough; don't bother truncating *)
+    if tree_depth tree > depth then
+      node_depth_truncate_ depth node
+    else
+      (* already short enough; don't bother truncating *)
      node

break-cases = vertical

-| Ok (`Version | `Help) -> Stdlib.exit 0
-| Error _ -> Stdlib.exit 1
+| Ok (`Version | `Help) ->
+    Stdlib.exit 0
+| Error _ ->
+    Stdlib.exit 1

-    ~f:(function `Int _ | `Float _ -> true | _ -> false)
+    ~f:(function
+      | `Int _
+      | `Float _ ->
+          true
+      | _ ->
+          false)

Formatting .mld files

Formatting .mld files as odoc documentation files is now possible! This will make it much easier to maintain high-quality documentation alongside your OCaml code.

This feature is only available in ocamlformat for now, but keep an eye on the future dune releases to know when dune fmt will be able to format your .mld files!

Various improvements and bugfixes

We fixed various issues related to indentation, alignment, and comments positioning.

Here are a few examples:

More consistent indentation inside a parenthesized expression:

        | [ node ] ->
            ( (if List.mem node ~set:integer_graph.(node)
-              then Has_loop [ numbering.forth.(node) ]
-              else No_loop numbering.forth.(node))
+               then Has_loop [ numbering.forth.(node) ]
+               else No_loop numbering.forth.(node))
            , component_edges.(component) )

    (let open Memo.O in
-    let+ w = Dune_rules.Workspace.workspace () in
-    Dune_engine.Execution_parameters.builtin_default
-    |> Dune_rules.Workspace.update_execution_parameters w);
+     let+ w = Dune_rules.Workspace.workspace () in
+     Dune_engine.Execution_parameters.builtin_default
+     |> Dune_rules.Workspace.update_execution_parameters w);

More consistent formatting of module expressions:

-  module Sel = (val if is_osx () then (module Mac)
-                    else if Sys.unix then (module Unix)
-                    else (module Fail) : Unix_socket)
+  module Sel =
+    (val if is_osx () then (module Mac)
+         else if Sys.unix then (module Unix)
+         else (module Fail)
+        : Unix_socket)

See full changelog

Library

The declaration of options is a regular module instead of a functor. (#2193, @EmileTrotignon)

Bug fixes

Fix indentation when ocamlformat is disabled on an expression (#2129, @gpetiot)
Reset max-indent when the max-indent option is not set (#2131, @hhugo, @gpetiot)
Add missing parentheses around immediate objects having attributes attached in 4.14 (#2144, @gpetiot)
Fix dropped comment attached to the identifier of an open-expression (#2155, @gpetiot)
Correctly format chunks of file in presence of enable/disable floating attributes (#2156, @gpetiot)
Remove abusive normalization in docstrings references (#2159, #2162, @EmileTrotignon)
Fix parentheses around symbols in if-then-else branches (#2169, @gpetiot)
Preserve position of comments around variant identifiers (#2179, @gpetiot)
Fix parentheses around symbol identifiers (#2185, @gpetiot)
Fix alignment inconsistency between let-binding and let-open (#2187, @gpetiot)
Fix reporting of operational settings origin in presence of profiles (#2188, @EmileTrotignon)
Fix alignment inconsistency of if-then-else in apply (#2203, @gpetiot)
Fix automated Windows build (#2205, @nojb)
Fix spacing between recursive module bindings and recursive module declarations (#2217, @gpetiot)
ocamlformat-rpc: use binary mode for stdin/stdout (#2218, @rgrinberg)
Fix interpretation of glob pattern in .ocamlformat-ignore under Windows (#2206, @nojb)
Remove conf mutability, and correctly display the conventional profile when using print-config (#2233, @EmileTrotignon)
Preserve position of comments around type alias (#2239, @EmileTrotignon)
Preserve position of comments around constructor record (#2237, @EmileTrotignon)
Preserve position of comments around external declaration strings (#2238, @EmileTrotignon, @gpetiot)
Preserve position of comments around module pack expressions (#2234, @EmileTrotignon, @gpetiot)
Correctly parenthesize array literals with attributes in argument positions (#2250, @ccasin)
Janestreet: Fix indentation of functions passed as labelled argument (#2259, @Julow)

Changes

Indent 2 columns after initializer keyword (#2145, @gpetiot)
Preserve syntax of generative modules ((struct end) vs ()) (#2135, #2146, @trefis, @gpetiot)
Preserve syntax of module unpack with type constraint (((module X) : (module Y)) vs (module X : Y)) (#2136, @trefis, @gpetiot)
Normalize location format for warning and error messages (#2139, @gpetiot)
Preserve syntax and improve readability of indexop-access expressions (#2150, @trefis, @gpetiot)
- Break sequences containing indexop-access assignments
- Remove unnecessary parentheses around indices
Mute warnings for odoc code blocks whose syntax is not specified (#2151, @gpetiot)
Improve formatting of odoc links (#2152, @gpetiot)
Preserve sugared extension node attached to an if carrying attributes (#2167, @trefis, @gpetiot)
Remove unnecessary parentheses around partially applied infix operators with attributes (#2198, @gpetiot)
JaneStreet profile: doesn't align infix ops with open paren (#2204, @gpetiot)
Re-use the type let_binding from the parser instead of value_binding, improve the spacing of let-bindings regarding of having extension or comments (#2219, @gpetiot)
The ocamlformat package now only contains the binary, the library is available through the ocamlformat-lib package (#2230, @gpetiot)

New features

Add a break-colon option to decide whether to break before or after the : symbol in value binding declarations and type constraints. This behavior is no longer ensured by ocp-indent-compat. (#2149, @gpetiot)
Format .mld files as odoc documentation files (#2008, @gpetiot)
New value vertical for option if-then-else (#2174, @gpetiot)
New value vertical for option break-cases (#2176, @gpetiot)
New value wrap-or-vertical for option break-infix that only wraps high precedence infix ops (#1865, @gpetiot)

OCaml Infrastructure: Promote watch.ocaml.org to Non-Beta Status

27 Feb 2023

infrastructure

watch.ocaml.org has been updated to run as a Docker service stack rather than via docker-compose. This change allowed an OCurrent pipeline to monitor the Docker repository and update the image via docker service update when a new version is available.

We have several other services updated via OCurrent: deploy.ci.ocaml.org

In OCurrent, we can create a schedule node that triggers every seven days and invokes a docker pull, yielding the current image SHA. If this has changed, run docker service update with the new image.

  let peertube =
     let weekly = Current_cache.Schedule.v ~valid_for:(Duration.of_day 7) () in
     let image = Cluster.Watch_docker.pull ~schedule:weekly "chocobozzz/peertube:production-bullseye" in
     Cluster.Watch_docker.service ~name:"infra_peertube" ~image ()

The deployment is achieved through an Ansible Playbook. Further details are available here.

The second part of the update was to improve the visibility of the backups for watch.ocaml.org. As noted previously, these use Tarsnap running monthly via CRON.

For this, a new plugin was added to OCurrent called ocurrent_ssh. This plugin allows arbitrary SSH commands to be executed as part of an OCurrent pipeline.

Again using a schedule node, the Current_ssh.run node will be triggered on a 30-day schedule, and the logs for each run will be available on deploy.ci.ocaml.org.

  let monthly = Current_cache.Schedule.v ~valid_for:(Duration.of_day 30) () in
   let tarsnap = Current_ssh.run ~schedule:monthly "watch.ocaml.org" ~key:"tarsnap" (Current.return ["./tarsnap-backup.sh"])

Merlin 4.8

27 Feb 2023

merlin platform

We are pleased to announce the release of Merlin 4.8 for OCaml 4.14.1 and 5.0.

This maintenance release brings multiple bug fixes and improvements to document fetching, jump-to-definition and type-on-hover for records' labels.

See full changelog

merlin binary
- Update internal typer to match OCaml 4.14.1 release (#1557)
- Improve type-enclosing behaviour when used on records' labels (#1565, fixes #1564)
- Restore compatibility with some OCaml compiler's debug flags that were incorrectly rejected by Merlin (#1556)
- Traverse aliases when jumping to declaration. This matches jump-to-definition's behavior (#1563)
- Improve locate's behavior in various ill-typed expressions (#1546, fixes #1567 and partially #1543)
- Correctly traverse patterns when looking for docs in the typedtree (#1572)
- Get documentation when the declaration or definition is selected (#1542, fixes #1540)
- On Windows, change to a harmless directory when launching server to avoid locking down current directory (#1569, fixes #1474)
test suite
- Add multiple tests for locate over ill-typed expressions (#1546)
- Add non-regression tests for other fixes in this release

OCamlFormat 0.25.0

24 Feb 2023

ocamlformat platform

OCamlFormat 0.25.0 is now available with expanded formatting capabilities!

This release addresses numerous inconsistencies and bugs, particularly around comment positioning, parentheses handling, and alignment issues. Key fixes include proper indentation when OCamlFormat is disabled on expressions, correct formatting of chunks with enable/disable attributes, and improved handling of comments around variant identifiers, type aliases, and constructor records. The release also resolves several platform-specific issues, including Windows build automation and glob pattern interpretation in .ocamlformat-ignore files.

New formatting options provide developers with more control over code layout. The break-colon option allows customization of line breaks around colons in value bindings and type constraints. Both if-then-else and break-cases options now support a vertical value for consistent vertical formatting. Additionally, OCamlFormat can now format .mld files as odoc documentation, and a new wrap-or-vertical value for break-infix provides more nuanced control over high-precedence infix operator wrapping.

See full changelog

Library

The declaration of options is a regular module instead of a functor. (#2193, @EmileTrotignon)

Bug fixes

Fix indentation when ocamlformat is disabled on an expression (#2129, @gpetiot)
Reset max-indent when the max-indent option is not set (#2131, @hhugo, @gpetiot)
Add missing parentheses around immediate objects having attributes attached in 4.14 (#2144, @gpetiot)
Fix dropped comment attached to the identifier of an open-expression (#2155, @gpetiot)
Correctly format chunks of file in presence of enable/disable floating attributes (#2156, @gpetiot)
Remove abusive normalization in docstrings references (#2159, #2162, @EmileTrotignon)
Fix parentheses around symbols in if-then-else branches (#2169, @gpetiot)
Preserve position of comments around variant identifiers (#2179, @gpetiot)
Fix parentheses around symbol identifiers (#2185, @gpetiot)
Fix alignment inconsistency between let-binding and let-open (#2187, @gpetiot)
Fix reporting of operational settings origin in presence of profiles (#2188, @EmileTrotignon)
Fix alignment inconsistency of if-then-else in apply (#2203, @gpetiot)
Fix automated Windows build (#2205, @nojb)
Fix spacing between recursive module bindings and recursive module declarations (#2217, @gpetiot)
ocamlformat-rpc: use binary mode for stdin/stdout (#2218, @rgrinberg)
Fix interpretation of glob pattern in .ocamlformat-ignore under Windows (#2206, @nojb)
Remove conf mutability, and correctly display the conventional profile when using print-config (#2233, @EmileTrotignon)
Preserve position of comments around type alias (#2239, @EmileTrotignon)
Preserve position of comments around constructor record (#2237, @EmileTrotignon)
Preserve position of comments around external declaration strings (#2238, @EmileTrotignon, @gpetiot)
Preserve position of comments around module pack expressions (#2234, @EmileTrotignon, @gpetiot)
Correctly parenthesize array literals with attributes in argument positions (#2250, @ccasin)

Changes

Indent 2 columns after initializer keyword (#2145, @gpetiot)
Preserve syntax of generative modules ((struct end) vs ()) (#2135, #2146, @trefis, @gpetiot)
Preserve syntax of module unpack with type constraint (((module X) : (module Y)) vs (module X : Y)) (#2136, @trefis, @gpetiot)
Normalize location format for warning and error messages (#2139, @gpetiot)
Preserve syntax and improve readability of indexop-access expressions (#2150, @trefis, @gpetiot)
- Break sequences containing indexop-access assignments
- Remove unnecessary parentheses around indices
Mute warnings for odoc code blocks whose syntax is not specified (#2151, @gpetiot)
Improve formatting of odoc links (#2152, @gpetiot)
Preserve sugared extension node attached to an if carrying attributes (#2167, @trefis, @gpetiot)
Remove unnecessary parentheses around partially applied infix operators with attributes (#2198, @gpetiot)
JaneStreet profile: doesn't align infix ops with open paren (#2204, @gpetiot)
Re-use the type let_binding from the parser instead of value_binding, improve the spacing of let-bindings regarding of having extension or comments (#2219, @gpetiot)
The ocamlformat package now only contains the binary, the library is available through the ocamlformat-lib package (#2230, @gpetiot)

New features

Add a break-colon option to decide whether to break before or after the : symbol in value binding declarations and type constraints. This behavior is no longer ensured by ocp-indent-compat. (#2149, @gpetiot)
Format .mld files as odoc documentation files (#2008, @gpetiot)
New value vertical for option if-then-else (#2174, @gpetiot)
New value vertical for option break-cases (#2176, @gpetiot)
New value wrap-or-vertical for option break-infix that only wraps high precedence infix ops (#1865, @gpetiot)

Dune 3.7.0

20 Feb 2023

dune platform

The dune team is pleased to announce the release of Dune 3.7.0.

As in the previous announce, here is a changelog split in several parts: changes to the dune executable itself (new commands or options, etc) and changes to the dune language. Most of the changes to the latter are only enabled when you opt-in to the new version by specifying (lang dune 3.7) in the corresponding dune-project file. In other words, it should always be safe to upgrade the dune package.

🌟 Spotlight Features

Watch mode for executables

Dune 3.7 now supports watch mode for executables! 🎉

It works just as you'd expect, if you define an executable, you can run it with

dune exec -w my-executable

It will interrupt the process when a file change and re-start the application.

For a practical example of the workflows enabled by watch-mode, check this demo of a live reload for web development:

Native Windows Polling

Starting from Dune 3.7, Dune watch mode is now available on Windows!

@yams-yams and @nojb from Lexifi have been working on integrating Windows native polling API with Dune to supplement the support for fswatch, which is unavailable on Windows.

Windows users can now run dune build -w out of the box!

Qualified Subdirs

It's quite common to organise your code into subdirectories to separate components. Until now, you could do this by including (include_subdirs unqualified) in your dune files, but this wasn't completely satisfying since all of your modules were available in the top-level. If you wanted to expose modules in subdirectories under another module, you had to create a separate library, which was.. quite the overhead.

Dune 3.7 brings support for the highly-anticipated qualified sub-directories. You can now write (include_subdirs qualified) in your dune file, and modules in your subdirectories will be exposed under a module with the name of the directory.

See full changelog

dune executable

Added

Allow running $ dune exec in watch mode (with the -w flag). In watch mode, $ dune exec the executed binary whenever it is recompiled. (#6966, @gridbugs)
Add a dune cache size command for displaying the size of the cache (#6638, @Alizter)
Allow $ dune ocaml dump-dot-merlin to run in watch mode. Also this command shouldn't print "Entering Directory" mesages. (#6497, @rgrinberg)
Add native support for polling mode on Windows (#7010, @yams-yams, @nojb, review by @Rucikir and @jbeckford)
Auto-detect dune-workspace files as dune files in Emacs (#7061, @ilankri)
Allow $ dune utop to load libraries defined in data only directories defined using (subdir ..) (#6631, @rgrinberg)

Changed

Make dune describe workspace return consistent dependencies for executables and for libraries. By default, compile-time dependencies towards PPX-rewriters are from now not taken into account (but runtime dependencies always are). Compile-time dependencies towards PPX-rewriters can be taken into account by providing the --with-pps flag. (#6727, fixes #6486, @esope)
Use colored output with MDX when Dune colors are enabled. (#6462, @MisterDA)
Use colored output with GCC and Clang when compiling C stubs. The flag -fdiagnostics-color=always is added to the :standard set of flags. (#4083, @MisterDA)
Move $ dune ocaml-merlin -dump-config=$dir to $ dune ocaml merlin dump-config $dir. (#6547, @rgrinberg)

Fixed

Fix parsing of OCaml errors that contain code excerpts with ... in them. (#7008, @rgrinberg)
Fix --trace-file output. Dune now emits a single complete event for every executed process. Unterminated async events are no longer written. (#6892, @rgrinberg)
Print missing newline after $ dune exec. (#6821, fixes #6700, @rgrinberg, @Alizter)
Fix binary corruption when installing or promoting in parallel (#6669, fixes #6668, @edwintorok)
Report an error if dune init ... would create a "dune" file in a location which already contains a "dune" directory (#6705, @gridbugs)
Fix the parsing of alerts. They will now show up in diagnostics correctly. (#6678, @rginberg)
Print "Leaving Directory" whenever "Entering Directory" is printed. (#6419, fixes #138, @cpitclaudel, @rgrinberg)
Remove "Entering Directory" messages for $ dune install. (#6513, @rgrinberg)
dune clean should no longer fail under Windows due to the inability to remove the .lock file. Also, bring the implementation of the global lock under Windows closer to that of Unix. (#6523, @nojb)
Fix missing dependencies when detecting the kind of C compiler we're using (#6610, fixes #6415, @emillon)
Remove spurious build dir created when running dune init proj ... (#6707, fixes #5429, @gridbugs)
Validate the command line arguments for $ dune ocaml top-module. This command requires one positional argument (#6796, fixes #6793, @rgrinberg)
Fix dependency cycle when installing files to the bin section with glob_files (#6764, fixes #6708, @gridbugs)
Handle "Too many links" errors when using Dune cache on Windows (#6993, @nojb)
Pre-emptively clear screen in watch mode (#6987, fixes #6884, @rgrinberg)
Allow --sandbox to affect ocamldep invocations. Previously, they were wrongly marked as incompatible (#6749, @rgrinberg)

dune language

Added

Allow (include_subdirs qualified) for OCaml projects. (#6594, fixes #1084, @rgrinberg)
Format dune files when they are named dune-file. This occurs when we enable the alternative file names project option. (#6566, @rgrinberg)
Add map_workspace_root dune-project stanza to allow disabling of mapping of workspace root to /workspace_root. (#6988, fixes #6929, @richardlford)
Allow the cinaps stanza to set a custom alias. By default, if the alias is not set then the cinaps actions will be attached to both @cinaps and @runtest (#6991, @rgrinberg)
Add (using ctypes 0.3). When used, paths in (ctypes) are interpreted relative to where the stanza is defined. (#6883, fixes #5325, @emillon)

Changed

Stop passing -q flag in dune coq top, which allows for .coqrc to be loaded. (#6848, fixes #6847, @Alizter)
Coq native mode is now automatically detected by Dune starting with Coq lang 0.7. (mode native) has been deprecated in favour of detection from the configuration of Coq. (#6409, @Alizter)
Accurately determine merlin configuration for all sources selected with copy# and copy_files#. The old heuristic of looking for a module in parent directories is removed (#6594, @rgrinberg)

Fixed

Fix parsing of the <= operator in blang expressions of dune files. Previously, the operator would be interpreted as <. (#6928, @tatchi)
Fix preprocessing with staged_pps (#6748, fixes #6644, @rgrinberg)
Fix the parsing of decimal and hexadecimal escape literals in dune, dune-package, and other dune s-expression based files (#6710, @shym)
Fix cross compilation configuration when a context with targets is itself a host of another context (#6958, fixes #6843, @rgrinberg)
Allow compilation rules to be impacted by (env ..) stanzas that modify the environment or set binaries. (#6527, @rgrinberg)
Fix handling of support files generated by odoc. (#6913, @jonludlam)
Fix the compilation of modules generated at link time when implicit_transitive_deps is enabled (#6642, @rgrinberg)
Fix inline tests with js_of_ocaml and whole program compilation mode enabled (#6645, @hhugo)
Fix js_of_ocaml separate compilation rules when --enable=effects ,--enable=use-js-string or --toplevel is used. (#6714, #6828, #6920, @hhugo)
Fix js_of_ocaml separate compilation in presence of linkall (#6832, #6916, @hhugo)
coqdep is now called once per theory, instead of one time per Coq file. This should significantly speed up some builds, as coqdep startup time is often heavy (#7048, @Alizter, @ejgallego)

Ppxlib 0.29.1

14 Feb 2023

ppxlib

See full changelog

Allow users to vendor ppxlib as-is, as well as ppx_sexp_conv in the same project (#386, @kit-ty-kate)

Ppxlib 0.29.0

13 Feb 2023

ppxlib

See full changelog

Remove File_path exports. (#381, @ceastlund)
Add Ppxlib.Expansion_helpers with name mangling utilities from ppx_deriving (#370, @sim642)

Dune 3.6.2

07 Feb 2023

dune platform

See full changelog

Fix configurator when using the MSVC compiler (#6538, fixes #6537, @nojb)
Fix running the RPC server on windows (#6721 fixes #6720, @rgrinberg)

Mdx 2.2.1

23 Jan 2023

mdx platform

See full changelog

Fixed

Undid the change to the pipe code to restore compatibility with Windows (#403, @MisterDA)

OCaml-LSP 1.15.1

19 Jan 2023

ocaml-lsp platform

See full changelog

Fixes

Fix race condition when a document was being edited and dune in watch mode was running (#1005, fixes #941, #1003)

Mdx 2.2.0

12 Jan 2023

mdx platform

See full changelog

Added

Report all parsing errors in Markdown files (#389, @NathanReb)

Changed

Preserve indentation in multiline OCaml blocks in .mli files (#395, @panglesd)
Rename the Normal syntax to Markdown to better explain what the syntax is and moved it to Mdx.Syntax (#412, @Leonidas-from-XIV)

Fixed

Fixed compatibility with Cmdliner 1.1.0 (#371, @Leonidas-from-XIV)
Report errors and exit codes of toplevel directives (#382, @talex5, @Leonidas-from-XIV)
Fix block locations in error reporting (#389, @NathanReb)
Include the content of the line that features the part-end MDX directive in the output, before that line would've been dropped (#374, #387, @Leonidas-from-XIV)
Handle EINTR signal on waitpid call by restarting the syscall. (#409, @tmcgilchrist)
Fix parsing of multiline toplevel phrases in .mli files (#394, #397, @Leonidas-from-XIV)

Removed

Removed warning about missing semicolons added in MDX 1.11.0 and the automatic insertion of semicolons in the corrected files introduced in MDX 2.0.0. (#398, @Leonidas-from-XIV)

OCaml-LSP 1.15.0

09 Jan 2023

ocaml-lsp platform

On behalf of the ocaml-lsp team, I’m pleased to announce ocaml-lsp-server versions 1.15.0-4.14 and 1.15.0-5.0 for OCaml 4.14 and 5.0, respectively. This is the first time we release ocaml-lsp supporting two compiler versions. We look forward to your feedback.

See full changelog

Features

Enable semantic highlighting support by default (#933)
Support connecting over pipes and socket. Pipes on Windows aren't yet supported (#946)

More about communication channels in LSP specification.
Re-enable ocamlformat-rpc for formatting code snippets (but not files and not on Windows) (#920, #939)

One needs to have installed either ocamlformat package version > 0.21.0 or, otherwise, ocamlformat-rpc package. Note that previously ocamlformat-rpc came in a standalone OPAM package, but since ocamlformat version > 0.21.0, it comes within ocamlformat package.
Add custom ocamllsp/hoverExtended request (#561)
Support utf-8 position encoding clients (#919)

More about position encoding in LSP specification.
Show unwrapped module alias types on hovering over module names. This is due to upgrading to merlin 4.7 and using merlin's verbosity=smart by default (#942)

Fixes

Respect the client's completion item resolve and preSelect capabilities (#925, #936)
Disable polling for dune's watch mode on Windows and OCaml 4.14.0 (#935)
Fix semantic highlighting of "long identifiers," e.g., Foo.Bar.x (#932)
Fix syncing of document contents:
- For ranges that span an entire line (#927)
- Previously, whole line edits would incorrectly eat the newline characters (#971)

Utop 2.11.0

06 Jan 2023

utop platform

See full changelog

Bump the compatibility to 4.08+ (#393 @emillon)
Load @toplevel_printer annotated printers for functors (#378 @metavinek)
Do not display a backtrace when exiting normally (#399 #398 @emillon)

Release of OCaml 4.14.1

20 Dec 2022

ocaml

We have the pleasure of celebrating the birthday of Oronce Finé by announcing the release of OCaml version 4.14.1.

This release is a collection of safe bug fixes, cherry-picked from the OCaml 5.0.0 release. If you were using OCaml 4.14.0 and cannot yet upgrade to OCaml 5, this release is for you.

The 4.14 branch is expected to receive more backported fixes during the maturation of OCaml 5. Thus don't hesitate to report any bugs on the OCaml issue tracker.

See the list of changes below for more details.

Installation Instructions

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

opam update
opam switch create 4.14.1

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

See full changelog

Changes in OCaml 4.14.1 (20 December 2022)

Compiler User-Interface and Warnings:

#11184, #11670: Stop calling ranlib on created / installed libraries (Sébastien Hinderer and Xavier Leroy, review by the same)

Build System:

#11370, #11373: Don't pass CFLAGS to flexlink during configure. (David Allsopp, report by William Hu, review by Xavier Leroy and Sébastien Hinderer)
#11487: Thwart FMA test optimisation during configure (William Hu, review by David Allsopp and Sébastien Hinderer)

Bug Fixes:

#10768, #11340: Fix typechecking regression when combining first class modules and GADTs. (Jacques Garrigue, report by François Thiré, review by Matthew Ryan)
#11204: Fix regression introduced in 4.14.0 that would trigger Warning 17 when calling virtual methods introduced by constraining the self type from within the class definition. (Nicolás Ojeda Bär, review by Leo White)
#11263, #11267: caml/{memory,misc}.h: Check whether _MSC_VER is defined before using it to ensure that the headers can always be used in code which turns on -Wundef (or equivalent). (David Allsopp and Nicolás Ojeda Bär, review by Nicolás Ojeda Bär and Sébastien Hinderer)
#11314, #11416: Fix non-informative error message for module inclusion (Florian Angeletti, report by Thierry Martinez, review by Gabriel Scherer)
#11358, #11379: Refactor the initialisation of bytecode threading, This avoids a "dangling pointer" warning of GCC 12.1. (Xavier Leroy, report by Armaël Guéneau, review by Gabriel Scherer)
#11387: Module type with constraints no longer crash the compiler in presence of both shadowing warnings and the -bin-annot compiler flag. (Florian Angeletti, report by Christophe Raffalli, review by Gabriel Scherer)
#11392, #11392: Assertion failure with -rectypes and external definitions (Gabriel Scherer, review by Florian Angeletti, report by Dmitrii Kosarev)
#11417: Fix a regression which allowed virtual methods in non-virtual classes. (Leo White, review by Florian Angeletti)
#11468: Fix regression from #10186 (OCaml 4.13) detecting IPv6 on Windows for Mingw-w64 i686 port. (David Allsopp, review by Xavier Leroy and Sébastien Hinderer)
#11489, #11496: More prudent deallocation of alternate signal stack (Xavier Leroy, report by @rajdakin, review by Florian Angeletti)
#11516, #11524: Fix the deprecated_mutable attribute. (Chris Casinghino, review by Nicolás Ojeda Bär and Florian Angeletti)
#11194, #11609: Fix inconsistent type variable names in "unbound type var" messages (Ulysse Gérard and Florian Angeletti, review Florian Angeletti and Gabriel Scherer)
#11622: Prevent stack overflow when printing a constructor or record mismatch error involving recursive types. (Florian Angeletti, review by Gabriel Scherer)
#11732: Ensure that types from packed modules are always generalised (Stephen Dolan and Leo White, review by Jacques Garrigue)
#11737: Fix segfault condition in Unix.stat under Windows in the presence of multiple threads. (Marc Lasson, Nicolás Ojeda Bär, review by Gabriel Scherer and David Allsopp)
#11776: Extend environment with functor parameters in strengthen_lazy. (Chris Casinghino and Luke Maurer, review by Gabriel Scherer)
#11533, #11534: Follow synonyms again in #show_module_type (this had stopped working in 4.14.0) (Gabriel Scherer, review by Jacques Garrigue, report by Yaron Minsky)
#11768, #11788: Fix crash at start-up of bytecode programs in no-naked-pointers mode caused by wrong initialisation of caml_global_data (Xavier Leroy, report by Etienne Millon, review by Gabriel Scherer)
#11803, #11808: On x86, the destination of an integer comparison must be a register; it cannot be a stack slot. (Vincent Laviron, review by Xavier Leroy, report by Emilio Jesús Gallego Arias)

OCaml-LSP 1.15.0~5.0preview1

16 Dec 2022

ocaml-lsp platform

See full changelog

Oops, we went looking but didn't find the changelog for this release 🙈

Release of OCaml 5.0.0

16 Dec 2022

ocaml

We have the pleasure of celebrating the birthdays of Jane Austen and Arthur C. Clarke by announcing the release of OCaml version 5.0.0.

The highlight of this new major version of OCaml is the long-awaited runtime support for shared memory parallelism and effect handlers.

This multicore support is the culmination of more than 8 years of effort, and required a full rewrite of the OCaml runtime environment. Consequently, OCaml 5.0.0 is expected to be a more experimental version of OCaml than the usual OCaml releases.

In this release, the native compiler only supports the x86-64 and arm64 architectures. In terms of operating systems, Linux, the BSDs, macOS and mingw64 on Windows are supported.

We are planning to restore the support for most previously supported architectures and operating systems, and address remaining known issues over the course of the next year.

Don't let those words of caution hinder your experimentation with OCaml 5: OCaml 5 as a language is fully compatible with OCaml 4 down to the performance characteristics of your programs. In other words, any code that works with OCaml 4 should work the same with OCaml 5.

The currently known exceptions to this rule are:

the removal of many long-deprecated functions and modules
changes to the internal runtime API
the performance of ephemerons is currently (and temporarily) strongly degraded.

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

During the maturing period for OCaml 5, the OCaml 4.14 branch will be maintained by backporting bug fixes from the OCaml 5 branch at regular intervals. The next release on the OCaml 4.14 branch, OCaml 4.14.1, should soon follow this release.

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 5.0.0

It might be also interesting to check the new support for parallelism by installing the domainslib library with

opam install domainslib

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

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.5.0.0+options <option_list>

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

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

The command line above is slightly more complicated for opam versions before 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.5.0.0+options,<option_list>

In both cases, all available options can be listed with opam search ocaml-option.

See full changelog

OCaml 5.0.0 (16 December 2022)

#10831: Multicore OCaml (Enguerrand Decorne, Stephen Dolan, Tom Kelly, Sadiq Jaffer, Anil Madhavapeddy, Sudha Parimala, KC Sivaramakrishnan, Leo White, the Tarides multicore team, review by Florian Angeletti, Damien Doligez, Xavier Leroy, Guillaume Munch-Maccagnoni, Olivier Nicole, Nicolás Ojeda Bär, Gabriel Scherer, the OCaml core development team, and many other valued reviewers.)

Runtime system:

#11400: Runtime events counters fixes Fixes mismatch between OCaml and C APIs, removes events from 4.x that are not present in the 5.0 GC and adds some missing probes. (Sadiq Jaffer, review by Gabriel Scherer, Florian Angeletti)
#11368: Runtime events buffer size OCAMLRUNPARAMS fix The runtime events buffer size can now be set via the 'e' OCAMLRUNPARAM. This is previously mistakenly enabled/disabled tracing instead. (Sadiq Jaffer, review by KC Sivaramakrishnan, David Allsopp, Damien Doligez)
#11308: Add environment variable to preserve runtime_events after exit If the environment variable OCAML_RUNTIME_EVENTS_PRESERVE exists then the runtime will not remove the runtime events ring buffers at exit. This makes tracing very short running programs more reliable. (Sadiq Jaffer, review by KC Sivaramakrishnan)
#10964: Ring-buffer based runtime tracing (runtime_events) Runtime_events is a very low overhead runtime tracing system designed for continuous monitoring of OCaml applications. (Sadiq Jaffer, review by Anil Madhavapeddy, Enguerrand Decorne, Richard Warburton, Gabriel Scherer, Sabine Schmaltz, Florian Angeletti, Patrick Ferris, Tom Kelly)

(breaking change) #10723: do not use -flat-namespace linking for macOS. (Carlo Cabrera, review by Damien Doligez)
(breaking change) #10863, #10933: Remove support for old, unprefixed C runtime function names such as alloc. The new names prefixed with caml_ must be used instead, such as caml_alloc. Consequently, it is no longer needed to define CAML_NAME_SPACE to avoid bringing unprefixed names into scope: this is now the default behavior. (Nicolás Ojeda Bär, review by Xavier Leroy)

#10902: Do not register empty code fragments in natdynlink. (David Allsopp, review by Xavier Leroy and Damien Doligez)
#10965: caml_fatal_error_hook, GC timing hooks, and caml_scan_roots_hook are now atomic variables. Restore GC timing hooks in multicore. (Guillaume Munch-Maccagnoni, review by Enguerrand Decorne, Xavier Leroy, Gabriel Scherer, and KC Sivaramakrishnan)
#11209: Add a public and thread-safe timing hook running at domain termination, after this domain has stopped running any OCaml code: caml_domain_terminated_hook. This can be useful for implementing domain-local state in C. (Guillaume Munch-Maccagnoni, review by Xavier Leroy and Gabriel Scherer)
#10875, #11731: Add option to allocate fiber stacks and sigaltstacks with mmap(MAP_STACK) instead of malloc. This is exposed via a configure --enable-mmap-map-stack option, and is enabled by default on OpenBSD where it is mandatory. (Anil Madhavapeddy, review by Gabriel Scherer, Tom Kelly, Michael Hendricks and KC Sivaramakrishnan).
#10950: Do not use mmap to allocate Caml_state. In order to reduce virtual memory usage, we dynamically allocate the domain_state structure. (Enguerrand Decorne, KC Sivaramakrishnan and Tom Kelly, review by Anil Madhavapeddy and Gabriel Scherer)
#11010: Use strerror_r for reentrant error string conversion. (Anil Madhavapeddy and Xavier Leroy, review by same and Edwin Török)
#11002, #11066, #11086: Do not use Begin_roots/End_roots macros in the runtime system. Also fix a missing root registration in the implementation of Unix.write on Windows. (Nicolás Ojeda Bär, Daniel Bünzli and Antonin Décimo, review by Xavier Leroy and David Allsopp)
#11022: Track GC work for all managed bigarray allocations (Stephen Dolan, report by Andrew Hunter, review by Damien Doligez)
#10802: Use 4.12 value macros and helpers in C code (Antonin Décimo, review by Gabriel Scherer)
#11105: Fix handling of fiber stack cache with multiple domains (Jon Ludlam, KC Sivaramakrishnan and Tom Kelly)
#11054: Respect user provided maximum stack space Make sure the stack we initially request is sized accordingly to the user provided settings. tmc/stack_space is also updated by this PR in order to account for this change. (Enguerrand Decorne, report by Jon Ludlam, review by Tom Kelly, KC Sivaramakrishnan and Gabriel Scherer)
#11238: Increase the default limit for the stack size to 128 Mi words, i.e. 1 Gib for 64-bit platforms and 512 Mib for 32-bit platforms. (Xavier Leroy, review by Sébastien Hinderer)

(breaking change) #11295: An ISO C 2011 compliant compiler, including full support for atomic types, is now required to build the OCaml runtime system. (Xavier Leroy, review by David Allsopp and Sébastien Hinderer)

#10915, #11039, #11057, #11095, #11190: Implement quality treatment for asynchronous actions in multicore. Reimplement the old behaviour of caml_process_pending* for multicore. (Guillaume Munch-Maccagnoni, review by Sadiq Jaffer and Gabriel Scherer)
#11303: Ensure that GC is not invoked from bounds check failures (Stephen Dolan, review by Sadiq Jaffer and Xavier Leroy)
#11304: Fix data race on Windows file descriptors (Olivier Nicole and Xavier Leroy, review by Xavier Leroy, David Allsopp, and Sadiq Jaffer)

(breaking change) #11337: pass 'flags' metadata to root scanners, to optimize stack scanning in the bytecode interpreter. Changes the interface of user-provided root-scanning hooks. (Gabriel Scherer, review by Xavier Leroy, Guillaume Munch-Maccagnoni, Sadiq Jaffer and Tom Kelly)

#11144: Restore frame-pointers support for amd64 (Fabrice Buoro, review by Frederic Bour and KC Sivaramakrishnan)

(breaking change) #11255: in the C interface, &Field(v, i) now has type volatile value * instead of value * in OCaml 4. This makes the memory model for mixed OCaml/C code better defined, but can cause warnings or type errors in user C code. (KC Sivaramakrishnan, review by Xavier Leroy, Gabriel Scherer and Guillaume Munch-Maccagnoni, additional discussions with Stephen Dolan and Luc Maranget)

#5299, #4787, #11138, #11272, #11506: To help debugging, Caml_state now dynamically checks that the domain lock is held, and fails otherwise (with a fatal error at most entry points of the C API, or systematically in debug mode). A new variable Caml_state_opt is introduced, and is NULL when the domain lock is not held. This allows to test from C code if the current thread holds the lock of its domain. (Guillaume Munch-Maccagnoni, review by Florian Angeletti, Damien Doligez, Sadiq Jaffer, Xavier Leroy, and Gabriel Scherer)
#11223: The serialization format of custom blocks changed in 4.08, but the deserializer would still support the pre-4.08 format. OCaml 5.x removed support for this old format; provide a clear error message in this case. (Hugo Heuzard, review by Gabriel Scherer)
#11504, #11522: Use static allocation in caml_make_float_vect in no-flat-float-array mode, it's more efficient and avoids a a race condition (Xavier Leroy, report by Guillaume Munch-Maccagnoni, review by David Allsopp)
#11652: Fix benign off-by-one error in Windows implementation of caml_mem_map. (David Allsopp, review by Gabriel Scherer)
#11669, #11704: Fix construction of Effect.Unhandled exceptions in the bytecode interpreter. (David Allsopp and Xavier Leroy, report by Samuel Hym, review by Xavier Leroy and Gabriel Scherer)

Code generation and optimizations:

#10972: ARM64 multicore support: OCaml & C stack separation; dynamic stack size checks; fiber and effects support. (Tom Kelly and Xavier Leroy, review by KC Sivaramakrishnan, Xavier Leroy Guillaume Munch-Maccagnoni, Eduardo Rafael, Stephen Dolan and Gabriel Scherer)

(breaking change) #10845 Emit frametable size on amd64 BSD (OpenBSD, FreeBSD, NetBSD) systems (emitted for Linux in #8805) (Hannes Mehnert, review by Nicolás Ojeda Bär)

Standard library:

#10742: Use LXM as the pseudo-random number generator for module Random. Add Random.State.split and Random.split to "split" a PRNG off another PRNG. (Xavier Leroy, review by Gabriel Scherer and Hugo Heuzard)

(breaking change) #10867, #11345: Remove deprecated values: Array.create, Array.make_float, Array.create_matrix, Bytes.uppercase, Bytes.lowercase, Bytes.capitalize, Bytes.uncapitalize, Char.lowercase, Char.uppercase, Filename.temp_dir_name, Int32.format, Int64.format, Nativeint.format, Format.bprintf, Format.kprintf, Format.set_all_formatter_output_functions, Format.get_all_formatter_output_functions, Format.pp_set_all_formatter_output_functions, Format.pp_get_all_formatter_output_functions, Format.pp_open_tag, Format.pp_close_tag, Format.open_tag, Format.close_tag, Format.formatter_tag_functions, Format.pp_set_formatter_tag_functions, Format.pp_get_formatter_tag_functions, Format.set_formatter_tag_functions, Format.get_formatter_tag_functions, Gc (mutability of the fields of type Gc.control), Lazy.lazy_from_fun, Lazy.lazy_from_val, Lazy.lazy_is_val, Obj.set_tag, Obj.truncate, Obj.final_tag, Obj.extension_constructor, Obj.extension_name, Obj.extension_id, Scanf.stdib, Scanf.fscanf, Scanf.kfscanf, Stdlib.( & ), Stdlib.( or ), String.set, String.copy, String.fill, String.unsafe_set, String.unsafe_fill, String.uppercase, String.lowercase, String.capitalize, String.uncapitalize, Thread.kill, Thread.wait_write, Thread.wait_read, the whole ThreadUnix module, the infix operator (.[]<-). (Nicolás Ojeda Bär, review by Damien Doligez)
(breaking change) #10896: Remove Stream, Genlex and Pervasives. Also remove legacy standalone bigarray library (the Bigarray module is now part of the standard library). (Nicolás Ojeda Bär, review by Kate Deplaix and Anil Madhavapeddy)

#10921: Use getentropy, when available, to seed the generator during Random.self_init (Michael Hendricks, review by Gabriel Scherer, Xavier Leroy, and Anil Madhavapeddy)

(breaking change) #10924: Add deprecated attribute to Printexc.catch, Printf.kprintf and Unix.SO_ERROR. (Nicolás Ojeda Bär, review by Damien Doligez)

#10986: Add Scanf.sscanf_opt, Scanf.bscanf_opt and Scanf.scanf_opt. (Nicolás Ojeda Bär, review by Florian Angeletti and Gabriel Scherer)

(breaking change) #11157: Rename "hash" in the "Hashtbl.SeededHashedType" signature to "seeded_hash". This allows defining both seeded and unseeded hash functions in the same module. (Nicolás Ojeda Bär, review by Gabriel Scherer and Xavier Leroy)

#8878: Add String.hash and String.seeded_hash. (Tom Kelly, review by Alain Frisch and Nicolás Ojeda Bär)

Other libraries:

(breaking change) #9071, #9100, #10935: Reimplement Thread.exit() as raising the exception Thread.Exit, and mark Thread.exit as deprecated. The new implementation changes the behavior compared with the OCaml 4 implementation. For example, the new implementation causes Fun.finally finalizers to be run and catch-all exception handlers to prevent termination. (Jacques-Henri Jourdan and Xavier Leroy, review by Damien Doligez, Guillaume Munch-Maccagnoni, Gabriel Scherer, and Enguerrand Decorne)

#11034: Dynlink library, add a global lock to make dynlinking thread-safe. (Florian Angeletti, review by Gabriel Scherer)
#11087: deprecate Thread.wait_timed_read, Thread.wait_timed_write, Thread.select, Thread.wait_pid. The same functionality is available in the Unix module. (Nicolás Ojeda Bär, review by Anil Madhavapeddy)
#11309, #11424, #11427, #11545: Add Domain.recommended_domain_count. (Christiano Haesbaert, Konstantin Belousov, review by David Allsopp, KC Sivaramakrishnan, Gabriel Scherer, Nicolas Ojeda Bar)
#11461, #11466: Fix gethostbyaddr for IPv6 arguments and make it domain-safe (Olivier Nicole, Nicolás Ojeda Bär, David Allsopp and Xavier Leroy, review by the same)
#11479: Make Unix.symlink domain-safe on Windows (Olivier Nicole, review by Xavier Leroy and David Allsopp)

Tools:

(breaking change) #11004: Litmus tests for checking the implementation of the memory model. (Luc Maranget, review by Gabriel Scherer and Xavier Leroy)

#11024: Handle alerts in ocamldoc. The alert [@@alert deprecated] is handled specifically and it's no longer needed to duplicate the deprecated annotation (the alert for the compiler and the tag for the documentation). Every other alerts also appear in the documentation. (Jules Aguillon, review by Florian Angeletti)
#11065: Port the bytecode debugger to 5.0, adding support for effect handlers. (Damien Doligez and @fabbing, review by @fabbing and Xavier Leroy)
#11079: Add the -nobanners option to dumpobj. (Sébastien Hinderer, review by Gabriel Scherer and Vincent Laviron)
#11100: Fix ocamltest to make sure failed tests are not counted as "unexpected error". (Damien Doligez, review by Sébastien Hinderer)
#11245: Merge the common code of ocamlcp and ocamloptp into a single module. (David Allsopp, review by Sébastien Hinderer)
#11382: OCamlmktop use a new initialization module "OCamlmktop_init" to preserve backward-compatibility with user-module provided modules that install toplevel printers. (Florian Angeletti, review by Gabriel Scherer and David Allsopp)

Manual and documentation:

#11058: runtime/HACKING.adoc tips on debugging the runtime (Gabriel Scherer, review by Enguerrand Decorne and Nicolás Ojeda Bär)
#11093: Add an effect handlers tutorial (KC Sivaramakrishnan, review by François Pottier, Gabriel Scherer, François Bobot and Wiktor Kuchta)
#11192: Better documentation for condition variables. (François Pottier, review by Luc Maranget, Xavier Leroy, and Wiktor Kuchta)
#11093: Add tutorials on parallelism features and the relaxed memory model (KC Sivaramakrishnan, review by Damien Doligez, Anil Madhavapeddy, Gabriel Scherer, Thomas Leonard, Tom Ridge, Xavier Leroy, Luc Maranget, Fabrice Buoro, Olivier Nicole, Guillaume Munch-Maccagnoni, Jacques-Henri Jourdan)
#11640: Add Flambda commonly-used options to the ocamlopt manpage (Amandine Nangah, review by David Allsopp, Florian Angeletti, Sébastien Hinderer, and Vincent Laviron)
#11676: Fix missing since annotation in the Sys and Format modules (Github user Bukolab99, review by Florian Angeletti)
#11813: Make new multicore chapters easier to discover, and emphasize impact on C bindings. (Edwin Török, review by KC Sivaramakrishnan, and Florian Angeletti)

Compiler user-interface and warnings:

#9140, #11131: New command-line flag -nocwd to not include implicit the current directory to the load path. (Thomas Roglin, review by Gabriel Scherer and Nicolás Ojeda Bär)
#11089: Add 'since ' information to compiler warnings. (André Maroneze, review by Florian Angeletti and Gabriel Scherer)
#10909: Disable warning 59 (assignment to immutable blocks) unless flambda invariant checks are enabled. (Vincent Laviron, review by Gabriel Scherer)
#10981, #11276: Implement a -cmi-file option for ocamlc and ocamlopt. (Sébastien Hinderer, review by Damien Doligez, Daniel Bünzli and Florian Angeletti)

(breaking change) #11049: Stop padding 1-digit compiler minor version numbers. (So for instance OCaml 5.0 rather than 5.00) (Sébastien Hinderer, review by David Allsopp, Florian Angeletti and Xavier Leroy)

#11184, #11670: Stop calling ranlib on created / installed libraries (Sébastien Hinderer and Xavier Leroy, review by the same)
#11253: Deprecate ocaml script and ocamlnat script where script has no extension and is an implicit basename. (David Allsopp, review by Florian Angeletti and Sébastien Hinderer)

Internal/compiler-libs changes:

#10878, #10909: restore flambda after the Multicore merge. (Vincent Laviron, review by Gabriel Scherer and Xavier Leroy)
#10864, #10888: restore afl-fuzz mode for sequential programs. (Jan Midtgaard, review by Xavier Leroy and Gabriel Scherer)
#11008, #11047: rework GC statistics in the Multicore runtime (Gabriel Scherer, review by Enguerrand Decorne)
#11058: basic debugging documentation in runtime/HACKING.adoc (Gabriel Scherer, review by Enguerrand Decorne and Nicolás Ojeda Bär)
#11199: Stop installing topdirs.cmi twice. The toplevel now reads topdirs.cmi from +compiler-libs, as the debugger does. (David Allsopp, review by Sébastien Hinderer)
#11007, #11399: META files for the stdlib, compiler-libs and other libraries (unix, dynlink, str, runtime_events, threads, ocamldoc) are now installed along with the compiler. (David Allsopp, Florian Angeletti, Nicolás Ojeda Bär and Sébastien Hinderer, review by Daniel Bünzli, Kate Deplaix, Anil Madhavapeddy and Gabriel Scherer)

Build system:

(breaking change) #10893: Remove configuration options --disable-force-safe-string and DEFAULT_STRING=unsafe as well as --enable-force-safe-string and DEFAULT_STRING=safe which are now the default unconditionally. (Kate Deplaix, review by Gabriel Scherer and David Allsopp)

#11092: Build native-code compilers on OpenBSD/aarch64. (Christopher Zimmermann, review by Anil Madhavapeddy)
#11126: Build system: make it possible to choose which ocamldep (and flags) to use when computing dependencies for the compiler. Add a -no-slash option to ocamldep to let users override -slash. (Sébastien Hinderer, review by David Allsopp)
#11147: Factorize the stdlib-related compilation flags. Make it possible to control them consistently through the STDLIBFLAGS build variable. Make sure ocamldoc and ocamllex get compiled and linked with debugging information (-g). (Sébastien Hinderer, review by Gabriel Scherer)
#11149: Make the bootstrap process reproducible on systems with non-big-endian floating point. If the boot/ artefacts are up-to-date, this means that running make bootstrap on any platform should not change the images in boot/ and paves the way for automated testing that the bootstrap is repeatable. (David Allsopp, review by Damien Doligez and Sébastien Hinderer)
#11160: otherlibs: merge win32unix into unix. (Sébastien Hinderer, review by David Allsopp, Nicolás Ojeda Bär, Xavier Leroy, Vincent Laviron and Antonin Décimo)

(breaking change) #11198, #11298: Install the Dynlink, Str and Unix libraries to individual subdirectories of LIBDIR. The compiler, debugger and toplevel automatically add -I +lib if required, but display an alert. (David Allsopp, review by Florian Angeletti, Nicolás Ojeda Bär, Valentin Gatien-Baron and Sébastien Hinderer)

#11200: Install ocamlprof's Profiling runtime module to a +profiling, removing it from the default namespace. (David Allsopp, review by Sébastien Hinderer)
#11294: Switch minimum required autoconf to 2.71. (David Allsopp, review by Xavier Leroy)
#11370, #11373: Don't pass CFLAGS to flexlink during configure. (David Allsopp, report by William Hu, review by Xavier Leroy and Sébastien Hinderer)
#11487: Thwart FMA test optimization during configure (William Hu, review by David Allsopp and Sébastien Hinderer)
#11097: Build native-code compilers on NetBSD/aarch64 (Kate Deplaix, review by Anil Madhavapeddy)

Bug fixes:

#10768, #11340: Fix typechecking regression when combining first class modules and GADTs. (Jacques Garrigue, report by François Thiré, review by Matthew Ryan)
#10790: don't drop variance and injectivity annotations when pretty printing with constraints (for example, with type +!'a t = ...). (Florian Angeletti, report by Luke Maurer, review by Matthew Ryan and Gabriel Scherer)
#11167: Fix memory leak from signal stack. (Antoni Żewierżejew, review by Gabriel Scherer and Enguerrand Decorne)
#11112: harden -use-runtime against spaces or quotes in the provided path (Gabriel Scherer, report by Brahima Dibassi, review by David Allsopp)
#11068, #11070: Fix typo in function name given in Unix_error exception for Unix.readlink on Windows. (David Allsopp, report by Xia Li-yao)
#10807: Don't duplicate standard handles in the child process spawned by win32unix Unix.create_process if the handles were already inheritable. Fix broken signalling of EOF on standard handles if they were already inheritable. (Antonin Décimo, review by Xavier Leroy and Nicolás Ojeda Bär)
#10868: Fix off-by-1 bug when initializing frame hashtables (Jonah Beckford, review by Tom Kelly, Nicolás Ojeda Bär and KC Sivaramakrishnan)
#11077: Make dumpobj compatible with absence of naked pointer support (Olivier Nicole and Jan Midtgaard, review by Gabriel Scherer)
#11111: fix fork() usage in ocamltest C code. When calling fork() from C code with the Multicore runtime active, one needs to call caml_atfork_hook() on the forked child before it can use the OCaml runtime. (Gabriel Scherer, review by Xavier Leroy, report by Brahima Dibassi)
#10809: Use the WSA_FLAG_NO_HANDLE_INHERIT on Windows when creating sockets with WSASocket if the cloexec (non-inheritable) parameter is true. Fixes a race condition where a child process could inherit the socket and deadlock the parent. (Antonin Décimo, review by Xavier Leroy)
#11194, #11609: Fix inconsistent type variable names in "unbound type var" messages (Ulysse Gérard and Florian Angeletti, review Florian Angeletti and Gabriel Scherer)
#11204: Fix regression introduced in 4.14.0 that would trigger Warning 17 when calling virtual methods introduced by constraining the self type from within the class definition. (Nicolás Ojeda Bär, review by Leo White)
#11263, #11267: caml/misc.h: check whether _MSC_VER is defined before using it to ensure that the headers can always be used in code which turns on -Wundef (or equivalent). (David Allsopp and Nicolás Ojeda Bär, review by Nicolás Ojeda Bär and Sébastien Hinderer)
#11289, #11405: fix some leaks on systhread termination (Fabrice Buoro, Enguerrand Decorne, Gabriel Scherer, review by Xavier Leroy and Florian Angeletti, report by Romain Beauxis)
#11314, #11416: fix non-informative error message for module inclusion (Florian Angeletti, report by Thierry Martinez, review by Gabriel Scherer)
#11358, #11379: Refactor the initialization of bytecode threading, This avoids a "dangling pointer" warning of GCC 12.1. (Xavier Leroy, report by Armaël Guéneau, review by Gabriel Scherer)
#11387, module type with constraints no longer crash the compiler in presence of both shadowing warnings and the -bin-annot compiler flag. (Florian Angeletti, report by Christophe Raffalli, review by Gabriel Scherer)
#11392, #11392: assertion failure with -rectypes and external definitions (Gabriel Scherer, review by Florian Angeletti, report by Dmitrii Kosarev)
#11417: Fix regression allowing virtual methods in non-virtual classes. (Leo White, review by Florian Angeletti)
#11468: Fix regression from #10186 (OCaml 4.13) detecting IPv6 on Windows for mingw-w64 i686 port. (David Allsopp, review by Xavier Leroy and Sébastien Hinderer)
#11482, #11542: Fix random crash in large closure allocation (Damien Doligez, report by Thierry Martinez and Vincent Laviron, review by Xavier Leroy)
#11508, #11509: make Bytes.escaped domain-safe (Christiano Haesbaert and Gabriel Scherer, review by Xavier Leroy, report by Jan Midtgaard and Tom Kelly)
#11516, #11524: Fix the deprecated_mutable attribute. (Chris Casinghino, review by Nicolás Ojeda Bär and Florian Angeletti)
#11576: Fix bug in Bigarray.Genarray.init in the the case of zero-dimensional arrays. (Nicolás Ojeda Bär, Jeremy Yallop, report by Masayuki Takeda, review by Jeremy Yallop and Florian Angeletti)
#11587: Prevent integer comparison from being used on pointers (Vincent Laviron, review by Gabriel Scherer)
#11622: Prevent stack overflow when printing a constructor or record mismatch error involving recursive types. (Florian Angeletti, review by Gabriel Scherer)
#11662, #11673: fix a memory leak when using Dynlink, the bug was only present in development version of OCaml 5. (Stephen Dolan, report by Andre Maroneze, review by Gabriel Scherer)
#11732: Ensure that types from packed modules are always generalised (Stephen Dolan and Leo White, review by Jacques Garrigue)
#11737: Fix segfault condition in Unix.stat under Windows in the presence of multiple threads. (Marc Lasson, Nicolás Ojeda Bär, review by Gabriel Scherer and David Allsopp)
#11776: Extend environment with functor parameters in strengthen_lazy. (Chris Casinghino and Luke Maurer, review by Gabriel Scherer)
#11533, #11534: follow synonyms again in #show_module_type (this had stopped working in 4.14.0) (Gabriel Scherer, review by Jacques Garrigue, report by Yaron Minsky)

opam 2.1.4

15 Dec 2022

opam platform

Feedback on this post is welcomed on Discuss!

We are pleased to announce the minor release of opam 2.1.4.

This opam release consists of backported fixes:

Make opam able to fully build with OCaml 5.0. dose3 >= 6.1 and base64 >= 3.1.0 are now required (#5357)
Fix a bug where opam would not output any explanation when a conflict arises when attempting to install a package (#5378)

Opam installation instructions (unchanged):

From binaries: run
```
bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.1.4"
```
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.
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)
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.

See full changelog

Add support for OCaml 5.0. Dose3 >= 6.1 and base64 >= 3.1.0 are now required [#5357 @kit-ty-kate @dra27 - fix #5354]
[BUG] Fix all empty conflict explanation messages [#5378 @kit-ty-kate - partial fix #4373]

Opam-publish 2.2.0

14 Dec 2022

opam-publish platform

We are pleased to announce the minor release of opam-publish 2.2.0.

This opam-publish release consists of the following breaking change:

Shorten the generated branch name. This is breaking change for people who want to force-push changes on an already opened PR using a previous version of opam-publish as the branch name might not be the same (#141)

and the following fixes:

Fix the github markdown syntax generated by opam-publish (#131)
Disambiguate GitHub archive URL computed from repository and tag (#135)
Upgrade to cmdliner >= 1.1.0 (#134)
Support git remotes with multiple push targets (#137)
Fix broken state if the initial opam-repository clone fails (#140)

... 3 4 5 ... 13

If you want to contribute to a new release announcement, check out the Contributing Guide on GitHub.