OCaml Changelog

We're happy to announce Utop 2.15.0 which adds support for OCaml 5.3.0!

We're pleased to announce the release of OCaml LSP Server 1.22.0, which enables experimental project-wide renaming of identifiers!

Merlin 5.4-503 is now available with support for OCaml 5.3. This release leverages new features in OCaml 5.3 to improve locate behavior, resolving issues where Merlin previously confused unique identifiers from interfaces and implementations. The indexer has been optimized to perform fewer merges, and initial support for project-wide renaming has been added, allowing occurrences to return all usages of related definitions across a project.

The Vim plugin receives an enhancement with search-by-type functionality, accessible through the existing :MerlinSearch command. The command now automatically switches between search-by-type and polarity search based on the first character of the query.

OCaml LSP Server version 1.21.0 is now available. This release introduces a new server option called standardHover that allows clients to disable the default hover provider functionality.

We’re happy to announce that we just released ppxlib.0.34.0.

The full patch notes are available on the release page over here.

The main features are OCaml 5.3 compatibility, new AST pretty-printing utilities and the ppxlib-tools package, support for [@@deriving ...] on class types and the addition of missing Pprintast entry points.

Changes summary

5.3 compatibility

ppxlib.0.34.0 is the first official ppxlib release that’s compatible with the new 5.3 compiler.

The ppxlib driver now also comes with a -keywords CLI option, similar to the compiler’s that allow you to compile and preprocess with the 5.3 compiler code that uses effect as an identifier. This is pretty niche but it’s there should you need it.

Please note that means you can use ppx-es with a 5.3 compiler but not that ppx-es can consume/produce 5.3 language features. We’re currently working on a fix allowing you to use the effect syntax in files that require preprocessing as it’s not possible with 0.34.0. The fix should be released in the next few days as 0.34.1.

AST pretty-printing

We added a new Pp_ast module that allows you to pretty print AST fragments.

The only way ppxlib would print ASTs before were as S-expressions. In practice we found that it was not always helpful and wanted a more readable and human friendly way of displaying the AST.

The default output of those printer is a simplified version of the AST to keep things clear and avoid cluttering the output with information that is not always useful. For example, if you run Ppxlib.Pp_ast.Default.expression on the AST for x + 2, you’ll get the following:

Pexp_apply
  ( Pexp_ident (Lident "+")
  , [ ( Nolabel, Pexp_ident (Lident "x"))
    ; ( Nolabel, Pexp_constant (Pconst_integer ( "2", None)))
    ]
  )

The alert reader will note that there are no locations or attributes and that the expression record layer is omitted here.

You can of course configure the printer to display more information if you need to.

We’ve been using these new printers internally to debug migration code and they have been a huge help so we hope they will make working with ppxlib easier for you too.

In addition to this new module, we also added a command line utility called ppxlib-pp-ast to pretty print ASTs from source files, source code fragments or even marshalled AST files. It is very similar to the old ppx_tools’s dumpast.

Note that it will print ppxlib’s internal AST after it’s been migrated from the installed compiler’s version. This is something that we could not simply achieve with OCaml’s own -dparsetree.

This should be a useful tool for debugging ppx related bugs or learning about the AST and we hope ppx authors and users will like it.

Other changes

As mentioned above, we also added some missing Pprintast* entries such as binding, longident and payload.

It is now possible to use [@@deriving ...] on class type declarations and therefore to write derivers for class types.

*: To the confused readers: Pprintast is entirely different from Pp_ast mentioned above as it prints the source code corresponding to a given AST.

Special thanks

We wanted to thank our external contributors for this release: @hhugo, @nojb and @dra27 for their help on the 5.3 compat and @mattiasdrp for bringing the Pprintast module up to speed.

Special thanks as well to @pedrobslisboa who started integrating their excellent ppx-by-example into ppxlib’s documentation.

Finally, I’d also like to thank the OCaml Software Foundation who’s been funding all my work on ppxlib and made this release possible!

Happy preprocessing to you all!

We are excited to share the release of OCaml-LSP 1.20.1, which introduces powerful new features and vital bug fixes to improve your development workflow. The new typeSearch request allows you to find values by type signature or polarity, making it easier to locate the functionality you need. Configurable MerlinJump actions and the custom jump request give you more control over code navigation. On the bug fix side, we have tackled issues like file descriptor leaks, enhanced method completion, and cleaned up duplicate responses in selectionRange.

This release introduces Merlin 5.3-502, compatible with OCaml 5.2, and 4.18-414, compatible with OCaml 4.14. Key updates include EXCLUDE_QUERY_DIR for better file management, resolving exceptions in polarity search,

and stabilizing type-enclosing results. For users of 5.3-502, additional enhancements address path resolution issues, fixes jump to fun functionality, and ensure proper handling of occurrences from hidden source files.

The Dune team is happy to announce the release of Dune 3.17.1!

This patch release includes some bug fixes. To reduce computing time, it does not build .cmxs files anymore when the (no_dynlink) stanza is used instead. This behavior also corrects the semantic of the (no_dynlink) stanza which was building but not installing .cmxs files. It does not try to build and install them anymore.

CHANGES:

Added

• Support OCaml 5.3 (#457, @anmonteiro, @samoht, @voodoos)
• Support multiple version labels in block headers. The block is active if all
  the version formulaes are satisfied (#458, @samoht)

Fixed

• Avoid infinite loop in lexer on unclosed code block (#444, @edwintorok)
• Fix support for skipped blocks in mli and mld files (#462, @samoht)

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

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

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

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

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

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

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

Feedback on this post is welcomed on Discuss!

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

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

Try it!

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

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

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

or from PowerShell for Windows systems

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

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

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

You should then run:

opam init --reinit -ni

Major breaking change: extra-files

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

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

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

Major changes

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Please report any issues to the bug-tracker.

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

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

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

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

More information can be found in the Discuss announcement.

Contributions are always welcome at Merlin | Issues

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

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

Feedback on this post is welcomed on Discuss!

We are pleased to announce the release of opam 2.2.1.

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

Changes

The three main changes are:

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

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

Try it!

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

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

or from PowerShell for Windows systems

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

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

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

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

Happy hacking!

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

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

documentation and a fix regarding the handling of OCamlFormat processes.

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

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

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

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

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

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

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

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

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

Notable features that are included in this release are:

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

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

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

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

Feedback on this post is welcomed on Discuss!

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

Try it!

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

The upgrade instructions are unchanged:

1. Either from binaries: run

For Unix systems

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

or from PowerShell for Windows systems

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

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

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

You should then run:

opam init --reinit -ni

Changes

Major change: Windows support

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

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

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

Major change: opam tree / opam why

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

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

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

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

Special thanks to @cannorin for contributing this feature.

Major change: with-dev-setup

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

For example

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

Major change: opam pin --recursive

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

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

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

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

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

New Options

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

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

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

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

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

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

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

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

Miscellaneous changes

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

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

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

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

Please report any issues to the bug-tracker.

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

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

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

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

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

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

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

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

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

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

We just released version 3.15.3 with some bug fixes.

Feedback on this post is welcomed on Discuss!

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

This opam release consists of backported bug fixes and improvements:

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

Opam installation instructions (unchanged):

1. From binaries: run

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

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

2. From source, using opam:

   opam update; opam install opam-devel
   

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

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

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

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

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

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

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

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

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

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

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

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

We just released version 3.15.2 with some bug fixes.

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

attempt at monorepo

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

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

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

Removal of previous limitations in many forms

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

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

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

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

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

Overlapping names in different contexts

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

Properly output UTF-8 encoded text when formatting

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

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

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

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

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

We're happy to announce that Dune 3.14.2 is now available.

Note that due to a regression that was detected before publishing to opam version 3.14.1 should not be used. The fix for the regression is part of this release.

This feature brings some small bugfixes around the handling of Coq as well as solves an issue where Dune is running on Windows in a path that contains Unicode characters. This affected e.g. users with diacritics or non-latin script in their name when running Dune within their home directory.

This release of UTop 2.14.0 brings support for the upcoming version of the compiler, OCaml 5.2.

We're thrilled to announce the release of Merlin 4.14, a significant update that introduces a suite of enhancements and fixes to improve your OCaml editor experience.

In addition to the improvements and bug fixes in this release, Merlin 4.14 is the first version to support the upcoming OCaml 5.2 compiler.

Some highlights in this release include:

• Improved Telemetry and Heap Usage Reporting: With the addition of the "heap_mbytes" field in server responses (#1717) and cache stats in telemetry (#1711), developers can now gain deeper insights into Merlin's performance and memory usage. These enhancements are part of our ongoing efforts to improve Merlin's performance profiling capabilities.
• SyntaxDocument Command: Addressing a common challenge among new users, the new SyntaxDocument command (#1706) enables you to find detailed information about the syntax element under the cursor directly from your editor. This feature aims to facilitate learning and code readability by providing instant access to syntax descriptions, making it easier for developers to familiarize themselves with OCaml's syntax.

Happy coding!

We're happy to announce that Dune 3.14.0 is now available. This feature has many fixes and new features that you can find in the changelog.

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

Dynamic dune files with (dynamic_include)

It is common for some parts of a build to be dynamic: for example a source file can be generated, or some parts of the configuration like C flags can be generated from a Dune rule. But until now it was not possible to generate rules dynamically.

For example, one might want to do it is to set up one rule per input file. This is a common pattern in test suites and is easy to do with Make. But Dune does not have a concept of parameterized rules, so it is necessary to set up one rule per input file.

The pattern to do this with Dune is to:

• Write a generator that lists the input files and emits Dune stanzas (as text);
• Add a rule that makes a dune.inc file using this generator;
• Add (include dune.inc) in the main dune file,

However, this requires checking in the generated dune.inc file in the repository. Another drawback is that when modifying the list of input files, it is necessary to run tests twice: one to update dune.inc, one to run the new test.

This release of Dune adds a new (dynamic_include) stanza that lifts these restrictions: dune.inc does not have to be part of the source tree, it can be generated transparently. This comes with some restrictions: some stanzas can not be generated, in particular the ones that define public libraries. And due to how rule loading works, the generated stanza needs to be defined in a different directory.

Still, this should be useful for many users that rely on the generate-include-commit pattern described above.

Sherlodoc integration

Sherlodoc is a search engine for OCaml documentation, which supports search by name, documentation and fuzzy type search (similar to Hoogle in the Haskell world). It can be obtained from opam using opam install sherlodoc.

When it is available, Dune commands that produce HTML documentation, such as dune build @doc and dune build @doc-new, will include a search bar in the generated output.

The ppxlib dev team is happy to announce the release of ppxlib.0.32.0.

The main feature of this release, implemented by @burnleydev1 during their Outreachy internship, is a huge improvement of the handling of located exceptions raised by ppx-es. Whenever a rewrite of the AST throws such an exception, the ppxlib driver catches it and resumes the rewriting using the latest valid AST it knows of. All caught exceptions are appended to the final AST as [%%ocaml.error ..] nodes. This means the driver returns a valid AST instead of one composed of a single error node corresponding to the first raised exception. This leads to a much better experience for ppx users as merlin now has a valid AST to work with when this happens, allowing it to properly function, reporting all errors, from ppx-es or otherwise. Note that despite this change we still recommend ppx authors to embed errors in the rewritten AST rather than throw exceptions.

The release also comes with a few bug fixes on longident parsing or windows compatibility and a new simplified API for ppx authors using attributes as flags (i.e. attributes without payloads such as [@ignore] for instance).

We'd like to thank our external contributors for this release:

• @burnleydev1 for their improvement of the driver exception handling
• @dianaoigo for their addition of the new attribute flags API
• @jonahbeckford for their fix of the windows compatibility

We'd also like to thank the OCaml Software Foundation who has been funding my work on this release.

We just released version 3.13.1 with some bugfixes.

The release of odoc 2.4.0 last month introduced a regression that caused Dune rules to fail in some cases. This release of odoc 2.4.1 fixes this issue.

We're happy to announce that Dune 3.13.0 is now available. This feature is packed with fixes and new features that you can find in the changelog.

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

Generate Conflicts File for Menhir Grammars (#9512, @nojb)

When menhir is used to generate code from .mly files, there are sometimes issues with the grammar itself, such as shift-reduce conflicts.

Menhir has an option to generate a "conflicts" file using its --explain flag, but until now this was not exposed by Dune. Starting from this version, this file will be generated automatically to help developers debug their grammars.

Cached Directory Targets (#9535, @rleshchinskiy)

Dune's global cache is a way to save the result of intermediate build results, even across projects. Previously, it would only work with file targets. With this change, it now supports Dune's experimental directory targets.

Dynamic Module List (#9578, @nojb)

In several places in the Dune language, it is possible to pass a list of modules. For example in a (library) stanza, if for some reason the default of picking all the source files in the current directory is not the right thing to do, it is possible to pass (module A B C) to only attach these modules to the library.

An important limitation has been that the list of modules needed to be static: written as is in the dune file. This limitation has now been lifted and it is possible to use (:include) or %{read-lines:file} in this field and similar ones.

LexiFi's use case is a system of static plug-ins: a program is extended by selecting which modules are linked to the application core. This list of modules can now be emitted by a generator that reads a configuration file.

Previously, this required using OCaml syntax for the dune file, which has several issues, including incompatibility with features like (include_subdirs) and poor performance because Dune does not know the dependencies of the generator and needs to re-run the build more times than necessary.

We just released version 3.12.2 with 2 bugfixes.

We are pleased to announce the release of OCaml LSP 1.17.0. This version comes packed with fixes and new features.

Notable features that come in this release include:

• Compatibility with Odoc 2.3.0: This version is fully compatible with Odoc 2.3.0, introducing support for the latest syntax features like tables and "codeblock output."
• New Actions for Code Cleanup: You can now mark or remove unused elements such as 'open', types, for loop indexes, modules, match cases, 'rec', and constructors, making your code cleaner and more efficient.
• Auto-completion for 'in' Keyword: To address the long standing issue of the in keyword completing to other terms in the editor, we've added auto-completion for this keyword in OCaml LSP. Typing in will now only suggest auto completion for the in keyword.

The odoc team is delighted to announce the release of odoc 2.4.0. It mainly contains support for search engines. There are of course bugfixes and smaller new features.

🌟 Spotlight Feature of Odoc 2.4.0 : Search

Odoc now support searching in the documentation ! The search is made to run in the browser, so that you do not need a server to enable search: you can have search on your documentation hosted on github pages or even locally on your machine.

No search engine is shipped with, you need to provide one, but all the facilities to make use of one are present. We adapted @art-w 's sherlodoc for seamless integration with odoc, alongside with new features. It is not yet released on opam, but we hope it will be soon.

You can already test sherlodoc and play with it on your own projects, there are instructions in its readme. Sherlodoc has fuzzy typed-based search like hoogle in the haskell world, and is made to work best for OCaml (unlike a general purpose search engine like elastic search).

Check the results on odoc's own online documentation : ocaml.github.io/odoc.

🤝 Join The Mission

While we are dedicated to developing the best tooling to generate and serve documentation on OCaml.org, creating a well-documented library ecosystem can only be a collective effort. Package authors: we’re working hard to give you great tools, but we’ll need all your help to create an ecosystem of well-documented libraries for OCaml!

If you find that writing documentation for your library isn’t as straightforward as you would like, please do share your feedback with us.