OCaml Changelog

Feedback on this post is welcomed on Discuss!

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

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

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

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

Changes

Windows support

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

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

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

opam-repository scalability

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

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

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

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

Other noteworthy changes

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

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

Windows Support

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

Stay tuned!

Try it!

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

The upgrade instructions are unchanged:

1. Either from binaries: run

   bash -c "sh <(curl -fsSL https://raw.githubusercontent.com/ocaml/opam/master/shell/install.sh) --version 2.2.0~beta2"
   

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

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

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

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

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

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

Removal of previous limitations in many forms

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

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

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

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

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

Overlapping names in different contexts

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

Properly output UTF-8 encoded text when formatting

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

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

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

We'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.

Feedback on this post is welcomed on Discuss!

We are happy to announce the first beta release of opam 2.2.0. It contains some fixes and a new feature for Windows. You can view the full list in the release note.

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

Major change: Check and advertise to use Git for Windows

Opam 2.2 is based on a Cygwin installation (previously installed, or managed internally by opam). Cygwin's Git has three known usability issues when used outside a Cygwin environment: it uses a different set of trusted certificate authorities, has its own Credential Manager and potentially uses a separate Git configuration. We therefore recommend using Git for Windows either installed manually or via winget.

At opam init, opam checks for available Git(s), and asks the user to choose one of the available, or to rerun opam init after installing another Git.

Other noteworthy changes

• When compiling opam on Windows with MinGW, the resulting opam binary now contains libstdc++ instead of requiring the DLL to be distributed alongside it or present in the environment
• Fix opam env containing carriage return on Cygwin - eval $(opam env) now works from a Cygwin bash terminal

Miscellaneous changes

• Remove stray comments from pwsh and cmd opam env output
• Add ./configure --enable-static to compile the opam binary statically on Linux
• Fix debug logs showing up regardless of verbosity on macOS 12.7.1 / 13.6.3 / 14.2 and FreeBSD
• Upgrade to, and require mccs >= 1.1+17
• Fix opam tree options --dev and --no-switch

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

Windows Support

The main opam-repository Windows compliance is still a work in progress, we recommend to use existing compatible repository (originally from @fdopen) and 32/64 bit mingw-w64 packages (by @dra27).

How to Test opam on Windows

If you're feeling adventurous, you can use the experimental pre-built binary for Windows available here.

Otherwise you can compile opam yourself using the following steps:

This beta requires a preexisting Cygwin installation for compiling opam.

1. 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

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

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

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

Try it!

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

The upgrade instructions are unchanged:

1. Either from binaries: run

   bash -c "sh <(curl -fsSL https://raw.githubusercontent.com/ocaml/opam/master/shell/install.sh) --version 2.2.0~beta1"
   

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

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

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

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

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.

We're happy to announce the release of Merlin 4.13. This release comes with a number of bug fixes to the Merlin binary.

It also introduces a new -cache-lifespan flag that can be used to set cache invalidation periods. This flag allows for fine-tuning of cache invalidation periods, enabling users to customize Merlin's internal configurations for optimal performance in various project contexts.

Additionally, this release includes several improvements in editor modes. For more details, we encourage you to delve into the full changelog.

We're pleased to announce the release of Dune 3.12!

Note that due to a mistake during the release process, version 3.12.0 was not published to opam and should not be used.

This version contains many fixes but we would like to highlight the following features:

• dune ocaml doc is a new command that will build the docs of your package, and open them in a web browser directly.
• a new set of odoc rules will build documentation for the whole switch. It can be invoked by dune build @doc-new. Note that this is still experimental.
• Dune can now be built and installed on Haiku.

Feedback on this post is welcomed on Discuss!

We are happy to announce the third alpha release of opam 2.2.0. It contains some fixes and a new feature for Windows. You can view the full list in the release note.

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

Major change: Environment variables handling on Windows

opam files now support a new x-env-path-rewrite field which specifies rewriting rules for the environment variable updates defined in the setenv and build-env fields. This field allows greater control over the separator character used for PATH-like fields (i.e. ; vs :), conversion of slashes to backslashes, and even conversion from Windows native path format (C:\cygwin64\home\dra\.opam) to Cygwin format (/home/dra/.opam).

The rewriting rules allow opam directory-like variables (e.g. the %{lib}% directory of a switch) to be used in setenv and build-env fields in a portable way.

For example, given:

setenv: [
  [PKG_CONFIG_PATH += "%{lib}%/pkgconfig"]
  [PATH += "%{share}%/bin"]
]
x-env-path-rewrite: [
  [ PKG_CONFIG_PATH ":" "host" ]
  [ PATH (":" {os != "win32"} | ";" {os = "win32"}) ("target" {os != "win32"} | "target-quoted" {os = "win32"}) ]
]

the environment variable changes given by opam env on Windows would be:

PKG_CONFIG_PATH='/cygdrive/c/Users/DRA/AppData/Local/opam/default/lib/pkgconfig[:<rest-of-PKG_CONFIG_PATH, if given>]'
PATH='C:\Users\DRA\AppData\Local\opam\default\share\bin;C:\Users\DRA\AppData\Local\opam\default\bin;<rest-of-PATH>'

with the following interesting parts for Windows users:

• PKG_CONFIG_PATH, which is consumed by a Cygwin-tool, has the directory given in Unix-like syntax, and opam's share variable was automatically converted
• The correct separator is used for each (: for PKG_CONFIG_PATH, ; for PATH is used when adding entries)
• In the PATH update, /bin was converted to \bin

Note that the specification for PATH is opam's default behaviour, so it's not actually necessary to have this formula for PATH in the x-env-path-rewrite field.

The full syntax is described in full in the manual.

Opam files carrying this new field are still compatible with the opam 2.0 syntax as it is an extension field, however its effect is only available with opam 2.2.0~alpha3 and above. If you want to make sure users of the package containing it have a compatible opam, you can use the available field to that end:

available: opam-version >= "2.2.0~alpha3"

or, if the change is Windows-specific:

available: opam-version >= "2.2.0~alpha3" | os != "win32"

Other noteworthy changes

• Sandbox: /tmp is now writable again, restoring POSIX compliance
• opam tree: opam tree package.version is now supported, displaying the dependency tree of a specific version of a package
• opam tree: --recurse and --subpath are supported for directory arguments
• opam admin: new add-extrafiles command to add/check/update the extra-files: field according to the files present in the files/ directory
• opam lint: new syntax allow marking a set of warnings as errors e.g. -W @1..9
• Releases: Pre-built binaries now include ppc64le and s390x

Miscellaneous changes

• A handful of issues related to the compilation of opam on Windows were fixed
• Bugs in the handling of the OPAMCURL, OPAMFETCH and OPAMVERBOSE environment variables were fixed
• Bugs in the handling of the --assume-built argument were fixed
• Sporadic crashes and segfaults during shell detection on Windows were fixed

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

Windows Support

The main opam-repository Windows compliance is still a work in progress, we recommend to use existing compatible repository (originally from @fdopen) and 32/64 bit mingw-w64 packages (by @dra27).

How to Test opam on Windows

If you're feeling adventurous, you can use the experimental pre-built binary for Windows available here. It should work but since it's our first public pre-built binary for Windows please use at your own risk.

Otherwise you can compile opam yourself using the following steps:

This alpha requires a preexisting Cygwin installation for compiling opam.

1. 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

2. Download & extract the opam archive
3. In the directory:

• if you are using MSVC: launch make cold
• if you are using MinGW: make sure the path to the libc dlls are in your PATH and launch make cold. For instance: export PATH='C:\cygwin64\usr\x86_64-w64-mingw32\sys-root\mingw\bin':$PATH && make cold. Don’t forget to update PATH accordingly or place the opam binary in the same directory as the libc dlls if you want to move the resulting opam binary.
• alternatively, if you're using MinGW: make cold CONFIGURE_ARGS=--with-private-runtime. If you change the location of the resulting opam binary, don't forget to copy Opam.Runtime.amd64 directory (or Opam.Runtime.i386) in the same directory.

4. A coffee later, you now have an opam executable!
5. Start your preferred Windows terminal (cmd or PowerShell), and initialise opam with the Windows sunset repository:

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

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

Try it!

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

The upgrade instructions are unchanged:

1. Either from binaries: run

   bash -c "sh <(curl -fsSL https://raw.githubusercontent.com/ocaml/opam/master/shell/install.sh) --version 2.2.0~alpha3"
   

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

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

You should then run:

opam init --reinit -ni

Please report any issues to the bug-tracker.

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

We’re pleased to announce the release of opam-publish 2.3.0.

This release, apart from a couple of light improvements, mainly consists of the following new option:

• You can now use opam-publish with the --no-confirmation argument for use in automated pipeline. Use this option with extreme caution if you do use it.

The full changelog is available below.

Enjoy, The opam team

Following the release of odoc 2.3.0, we're releasing a patch release with odoc 2.3.1 that fixes support for OCaml 5.1.

After giving space for feedback and objections by the community, we have deprecated ocaml-migrate-parsetree (aka OMP). It is superseded by Ppxlib.

There are four major differences between OMP and Ppxlib, which all go hand in hand.

The first major difference is in the library and therefore impacts how to write PPXs. With OMP, each PPX author had to choose a parsetree version to define their PPX against. There was no version agreement between different PPXs. With Ppxlib, each PPX author uses the same parsetree version.

The second major difference is about compatibility with new compiler syntax. While with OMP, each PPX was on its own parsetree version, Ppxlib keeps them all on the version of the latest stably released compiler. That makes using any PPX compatible with using the latest compiler syntax features!

The third major difference is in the philosophy of PPXs. With OMP, all PPX transformations were global transformations, i.e., transformations of the whole parsetree. Ppxlib has introduced the concept of "context-free" transformations, i.e., transformations that transform only one parsetree node. By restricting their scope of action, context-free PPXs are a lot more predictable and less dangerous! Also, Ppxlib merges all context-free PPXs into one parsetree pass, defining clear semantics of PPX composition.

The fourth major difference is in the driver, i.e., the binary that drives the application of all used PPXs in a project. The Ppxlib driver is significantly more performant than the OMP driver used to be. That's partly because it does a lot fewer parsetree migrations and partly thanks to merging all context-free PPXs into one parsetree pass.

As a consequence of the deprecation, OMP will be incompatible with any new compiler version. The first incompatible compiler version is OCaml 5.1.

Thanks a lot to everyone involved in OCaml's transition from OMP to Ppxlib, for example by porting their PPX!

Following the release of Dune 3.11.0 a few days ago, we've just released version 3.11.1 with a couple of bug fixes:

• Fix the dune rpc status command that was incorrectly showing that there were no RPC servers running on Windows.
• Fix a bogus error when no inline test was declared in a library using (inline_tests).

We're happy to announce the release of Ppxlib 0.31.0. Shortly after OCaml 5.1.0 has been released, this Ppxlib release fixes a bug in the support of OCaml 5.1.0. Before that bug fix, the warnings about a generative/applicative mismatch between a functor creation and its application introduced by OCaml 5.1.0 were also triggered when that mismatch didn't exist.

Furthermore, the release contains a couple of bug fixes in the context of attributes.

We're also excited about two main enhancements. One allows authors of extension node rewriters to add a path argument to the extension node. That's excellent for hygiene since it allows the PPX to be explicit about modules rather than depending on its scope.

The other main enhancement allows an opt-in for compiler warnings about unused code generated by derivers (warnings w32 and w60). That opting in needs to happen on both sides of the deriver, the writer side and the user side. Opting in to those code warnings will help to clean up unused code, leading to performance improvements in compilation and editor support.

We're pleased to announce the release of Dune 3.11!

Here are some highlights from this release.

Dune Terminal User Interface (TUI)

The biggest highlight in this release is the introduction of the new Terminal User Interface (TUI) display mode.

You can now run dune build --display tui to open a TUI. We recommend using it in conjunction with Dune watch mode (dune build -w --display tui).

From the TUI, you will be able to navigate messages from Dune build, scroll through them, or click to minimize them. Press ? to show the help screen.

Installing Source Directories

Another exciting feature in this release is the new (source_trees ..) field added to the (install ..) stanzas to add every files in a directory to the installation. For instance, to add your manual to the installation, you can use:

(install
 (section doc)
 (source_trees manual))

Let us know what you think about these features, and don't hesistate to open issues on Dune's bug tracker if you encounter any issue.

We are thrilled to announce the release of odoc 2.3.0! 🎉 This release is the result of almost a year of diligent work from the odoc team since the last major release of odoc 2.2.0, it comes packed with significant new features and improvements!

🌟 Spotlight Features of Odoc 2.3.0

Here are a couple of the new features introduced in Odoc 2.3.0 that we'd like to highlight.

Table Support

Table support is the last addition to the odoc language, and comes with two syntax flavours: a light one, and a heavy one. The light markup is similar to markdown's markup for table, producing tables that are readable in the source file as well.

However, this markup has some limitation, since it only allows inline content in cells. It can also be difficult to read and mantain for big tables, without a proper editor support. For this reason, Odoc also provides a "heavy" markup, closer to the html one, with fewer limitations!

Here is a table in heavy, light, and rendered form:

{t
Table | support
------|--------
is    | cool!
}

{table
{tr {th Table} {th support}}
{tr {td is} {td cool!}}
}

Table | support ------|-------- is | cool!

Source Code Rendering

Source code rendering is an extremely exciting new feature. Not only odoc is now able to generate a rendering of the source files (and source hierarchy) of a project, but it is also able to create direct links from the documentation to the implementation!

This puts the documentation browsing to a new level, by helping to quickly answer any implementation-related question!

The source code rendering is also tailored to OCaml, for instance with links from variables to their definition, something missing from traditional html-based source viewing such as github!

Using this features in odoc’s driver will require some work, but you can already have a preview of the feature by going to the odoc API website, which was built with the feature enabled. For instance, the Odoc_html 19 module is now populated with many Source links, jumping right into the implementation file 5! Directory pages to browser the implementation are also included 8 :smiley:

🗺️ Background & Roadmap

Some background on our roadmap and what comes next.

The lack of access to comprehensive documentation for OCaml libraries is one of the biggest pain points reported by the OCaml community, as highlighted in the 2022 OCaml survey (c.f. Q50).

This motivated the odoc and OCaml.org teams to jointly work on a centralised package documentation, that went live in April 2022, as part of the new version of OCaml.org.

With documentation for OCaml libraries readily available on OCaml.org, we now turn our focus on making sure that library authors have the tooling they need to create high-quality documentation.

Our roadmap highlights some features we believe will make the generated documentation significantly better for readers, and documentation-writing much more pleasant and rewarding.

This release is a significant milestone in implementing the features on our roadmap and is the precursor to a series of upcoming releases. Odoc 2.4.0 will follow shortly and will bring support for search. Stay tuned and follow our progress through the OCaml Platform newsletter!

🤝 Join Our 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.

We are happy to announce the release of MDX 2.3.1! This is the first release of MDX to be compatible with OCaml 5.1.

We've also vendored the odoc-parser library, eliminating the need to have it as a dependency. MDX can now be installed independently of the odoc version you're using.

Merlin 4.12 is a small patch release fixing regressions introduced in previous versions.

We are pleased to announce the release of Merlin 4.11 for OCaml 4.14.1, 5.0, and 5.1.

This release brings official support for OCaml 5.1 and introduces some changes to Emacs' default bindings proposed by the community:

• Unbind C-c C-r (to avoid shadowing tuareg-eval-region) and bind C-c C-v instead to merlin-error-check;
• Rebind C-c C-d to merlin-document and bind C-c M-d and C-c | instead to merlin-destruct;
• Bind C-u C-c C-t to merlin-type-expr.

Thanks to everyone involved!

We are pleased to announce the release of OCamlFormat 0.26.1!

This is the first OCamlFormat release to be compatible with OCaml 5.1.

We highlight notable formatting improvements below:

1. Removal of extra breaks in constructor declarations

 type t =                               
   | Foo
   | (* Redirect (None, lib) looks up lib in the same database *)
-    Redirect of
-      db option * (Loc.t * Lib_name.t)
+    Redirect of db option * (Loc.t * Lib_name.t)
+    

2. Consistent formatting for arrow class types, and consistent indentation of the object keyword

module type S = sig                    
-  class tttttttttttt : aaaaaaaaaaaaaaaaaa:int -> bbbbbbbbbbbbbbbbbbbbb:float ->
+  class tttttttttttt :
+    aaaaaaaaaaaaaaaaaa:int ->
+    bbbbbbbbbbbbbbbbbbbbb:float ->
    cccccccccccccccccccc
end

class type ct =
  let open M in
-  object
+object
  val x : t
end

We've also fixed a few bugs. Attributes that were previously skipped are not preserved, and we fixed a crash that occured in the presence of nested modules.

Have a look at the full changelog to see the list of improvements, and don’t hesitate to share your feedback on this release on OCaml Discuss.

We're thrilled to announce the release of Merlin 4.10, which comes with many bug fixes and improvements.

One of the standout features of this release is the significantly enhanced support for binding operators like let+ and and+. You'll find that the results from type-enclosing on expressions that contain let bindings are now more precise.

As OCaml 5.1 is on the horizon, we're excited to announce the release of odoc 2.2.1. This latest version brings compatibility with the upcoming OCaml 5.1 release.