We are pleased to announce a first release candidate for the long-awaited opam 2.0.0.

A lot of polishing has been done since the last beta, including tweaks to the built-in solver, allowing in-source package definitions to be gathered in an opam/ directory, and much more.

With all of the 2.0.0 features getting pretty solid, we are now focusing on bringing all the guides up-to-date¹, updating the tools and infrastructure, making sure there are no usability issues with the new workflows, and being future-proof so that further updates break as little as possible.

You are invited to read the beta5 announcement for details on the 2.0.0 features. Installation instructions haven't changed:

1. From binaries: run

   sh <(curl -sL https://opam.ocaml.org/install.sh)
   

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

2. From source, using opam:

   opam update; opam install opam-devel
   

   (then copy the opam binary to your PATH as explained)

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

Thanks a lot for testing out the RC and reporting any issues you may find. See what we need tested for more detail.

¹ You can at the moment rely on the manpages, the Manual, and of course the API, but other pages might be outdated.

After a few more months brewing, we are pleased to announce a new beta release of opam. With this new milestone, opam is reaching feature-freeze, with an expected 2.0.0 by the beginning of next year.

This version brings many new features, stability fixes, and big improvements to the local development workflows.

What's new

The features presented in past announcements: local switches, in-source package definition handling, extended dependencies are of course all present. But now, all the glue to make them interact nicely together is here to provide new smooth workflows. For example, the following command, if run from the source tree of a given project, creates a local switch where it will restore a precise installation, including explicit versions of all packages and pinnings:

opam switch create ./ --locked

this leverages the presence of opam.locked or <name>.opam.locked files, which are valid package definitions that contain additional details of the build environment, and can be generated with the opam-lock plugin (the lock command may be merged into opam once finalised).

But this new beta also provides a large amount of quality of life improvements, and other features. A big one, for example, is the integration of a built-in solver (derived from mccs and glpk). This means that the opam binary works out-of-the box, without requiring the external aspcud solver, and on all platforms. It is also faster.

Another big change is that detection of architecture and OS details is now done in opam, and can be used to select the external dependencies with the new format of the depexts: field, but also to affect dependencies or build flags.

There is much more to it. Please see the changelog, and the updated manual.

How to try it out

Our warm thanks for trying the new beta and reporting any issues you may hit.

1. The easiest is to use our pre-compiled binaries. This script will also make backups if you migrate from 1.x, and has an option to revert back:

   sh <(curl -sL https://opam.ocaml.org/install.sh)
   

   This uses the binaries from https://github.com/ocaml/opam/releases/tag/2.0.0-beta5

2. Another option is to compile from source, using an existing opam installation. Simply run:

   opam update; opam install opam-devel
   

   and follow the instructions (you will need to copy the compiled binary to your PATH).

3. Compiling by hand from the inclusive source archive, or from the git repo. Use ./configure && make lib-ext && make if you have OCaml >= 4.02.3 already available; make cold otherwise.

   If the build fails after updating a git repo from a previous version, try git clean -fdx src/ to remove any stale artefacts.

Note that the repository format is different from that of opam 1.2. Opam 2 will be automatically redirected from the opam-repository to an automatically rewritten 2.0 mirror, and is otherwise able to do the conversion on the fly (both for package definitions when pinning, and for whole repositories). You may not yet contribute packages in 2.0 format to opam-repository, though.

What we need tested

We are interested in all opinions and reports, but here are a few areas where your feedback would be specially useful to us:

• Use 2.0 day-to-day, in particular check any packages you may be maintaining. We would like to ensure there are no regressions due to the rewrite from 1.2 to 2.0.
• Check the quality of the solutions provided by the solver (or conflicts, when applicable).
• Test the different pinning mechanisms (rsync, git, hg, darcs) with your project version control systems. See the --working-dir option.
• Experiment with local switches for your project (and/or opam install DIR). Give us feedback on the workflow. Use opam lock and share development environments.
• If you have any custom repositories, please try the conversion to 2.0 format with opam admin upgrade --mirror on them, and use the generated mirror.
• Start porting your CI systems for larger projects to use opam 2, and give us feedback on any improvements you need for automated scripting (e.g. the --json output).

UPDATE (2017-02-14): A beta2 is online, which fixes issues and performance of the opam build command. Get the new binaries, or recompile the opam-devel package and replace the previous binary.

We are pleased to announce that the beta release of opam 2.0 is now live! You can try it already, bootstrapping from a working 1.2 opam installation, with:

opam update; opam install opam-devel

With about a thousand patches since the last stable release, we took the time to gather feedback after our last announcement and implemented a couple of additional, most-wanted features:

• An opam build command that, from the root of a source tree containing one or more package definitions, can automatically handle initialisation and building of the sources in a local switch.
• Support for repository signing through the external Conex tool, being developed in parallel.

There are many more features, like the new opam clean and opam admin commands, a new archive caching system, etc., but we'll let you check the full changelog.

We also improved still on the already announced features, including compilers as packages, local switches, per-switch repository configuration, package file tracking, etc.

The updated documentation is at https://opam.ocaml.org/doc/2.0/. If you are developing in opam-related tools, you may also want to browse the new APIs.

Try it out

Please try out the beta, and report any issues or missing features. You can:

• Build it from source in opam, as shown above (opam install opam-devel)
• Use the pre-built binaries.
• Building from the source tarball: download here and build using ./configure && make lib-ext && make if you have OCaml >= 4.01 already available; make cold otherwise
• Or directly from the git tree, following the instructions included in the README. Some files have been moved around, so if your build fails after you updated an existing git clone, try to clean it up (git clean -dx).

Some users have been using the alpha for the past months without problems, but you may want to keep your opam 1.2 installation intact until the release is out. An easy way to do this is with an alias:

alias opam2="OPAMROOT=~/.opam2 path/to/opam-2-binary"

Changes to be aware of

Command-line interface

• opam switch create is now needed to create new switches, and opam switch is now much more expressive
• opam list is also much more expressive, but be aware that the output may have changed if you used it in scripts
• new commands:
  • opam build: setup and build a local source tree
  • opam clean: various cleanup operations (wiping caches, etc.)
  • opam admin: manage software repositories, including upgrading them to opam 2.0 format (replaces the opam-admin tool)
  • opam env, opam exec, opam var: shortcuts for the opam config subcommands
• opam repository add will now setup the new repository for the current switch only, unless you specify --all
• Some flags, like --test, now apply to the packages listed on the command-line only. For example, opam install lwt --test will build and install lwt and all its dependencies, but only build/run the tests of the lwt package. Test-dependencies of its dependencies are also ignored
• The new opam install --soft-request is useful for batch runs, it will maximise the installed packages among the requested ones, but won't fail if all can't be installed

As before, opam is self-documenting, so be sure to check opam COMMAND --help first when in doubt. The bash completion scripts have also been thoroughly improved, and may help navigating the new options.

Metadata

There are both a few changes (extensions, mostly) to the package description format, and more drastic changes to the repository format, mainly related to translating the old compiler definitions into packages.

• opam will automatically update, internally, definitions of pinned packages as well as repositories in the 1.2 format
• however, it is faster to use repositories in the 2.0 format directly. To that end, please use the opam admin upgrade command on your repositories. The --mirror option will create a 2.0 mirror and put in place proper redirections, allowing your original repository to retain the old format

The official opam repository at https://opam.ocaml.org remains in 1.2 format for now, but has a live-updated 2.0 mirror to which you should be automatically redirected. It cannot yet accept package definitions in 2.0 format.

Package format

• Any available: constraints based on the OCaml compiler version should be rewritten into dependencies to the ocaml package
• Separate build: and install: instructions are now required
• It is now preferred to include the old url and descr files (containing the archive URL and package description) in the opam file itself: (see the new synopsis: and description: fields, and the url {} file section)
• Building tests and documentation should now be part of the main build: instructions, using the {test} and {doc} filters. The build-test: and build-doc: fields are still supported.
• It is now possible to use opam variables within dependencies, for example depends: [ "foo" {= version} ], for a dependency to package foo at the same version as the package being defined, or depends: [ "bar" {os = "linux"} ] for a dependency that only applies on Linux.
• The new conflict-class: field allows mutual conflicts among a set of packages to be declared. Useful, for example, when there are many concurrent, incompatible implementations.
• The ocaml-version: field has been deprecated for a long time and is no longer accepted. This should now be a dependency on the ocaml package
• Three types of checksums are now accepted: you should use md5=<hex-value>, sha256=<hex-value> or sha512=<hex-value>. We'll be gradually deprecating md5 in favour of the more secure algorithms; multiple checksums are allowed
• Patches supplied in the patches: field must apply with patch -p1
• The new setenv: field allows packages to export updates to environment variables;
• Custom fields x-foo: can be used for extensions and external tools
• """ delimiters allow unescaped strings
• & has now the customary higher precedence than | in formulas
• Installed files are now automatically tracked meaning that the remove: field is usually no longer required.

The full, up-to-date specification of the format can be browsed in the manual.

Repository format

In the official, default repository, and also when migrating repositories from older format versions, there are:

• A virtual ocaml package, that depends on any implementation of the OCaml compiler. This is what packages should depend on, and the version is the corresponding base OCaml version (e.g. 4.04.0 for the 4.04.0+fp compiler). It also defines various configuration variables, see opam config list ocaml.
• Three mutually-exclusive packages providing actual implementations of the OCaml toolchain:
  • ocaml-base-compiler is the official releases
  • ocaml-variants.<base-version>+<variant-name> contains all the other variants
  • ocaml-system-compiler maps to a compiler installed on the system outside of opam

The layout is otherwise the same, apart from:

• The compilers/ directory is ignored
• A repo file should be present, containing at least the line opam-version: "2.0"
• The indexes for serving over HTTP have been simplified, and urls.txt is no longer needed. See opam admin index --help
• The archives/ directory is no longer used. The cache now uses a different format and is configured through the repo file, defaulting to cache/ on the same server. See opam admin cache --help

Feedback

Thanks for trying out the beta! Please let us have feedback, preferably to the opam tracker; other options include the opam-devel list and #opam IRC channel on Freenode.

We are pleased to announce a preview release for opam 2.0, with over 700 patches since 1.2.2. Version 2.0~alpha4 has just been released, and is ready to be more widely tested.

This version brings many new features and changes, the most notable one being that OCaml compiler packages are no longer special entities, and are replaced by standard package definition files. This in turn means that opam users have more flexibility in how switches are managed, including for managing non-OCaml environments such as Coq using the same familiar tools.

A Few Highlights

This is just a sample, see the full changelog for more:

• Sandboxed builds: Command wrappers can be configured to, for example, restrict permissions of the build and install processes using Linux namespaces, or run the builds within Docker containers.

• Compilers as packages: This brings many advantages for opam workflows, such as being able to upgrade the compiler in a given switch, better tooling for local compilers, and the possibility to define coq as a compiler or even use opam as a generic shell scripting engine with dependency tracking.

• Local switches: Create switches within your projects for easier management. Simply run opam switch create <directory> <compiler> to get started.

• Inplace build: Use opam to build directly from your source directory. Ensure the package is pinned locally then run opam install --inplace-build.

• Automatic file tracking:: opam now tracks the files installed by packages and is able to cleanly remove them when no existing files were modified. The remove: field is now optional as a result.

• Configuration file: This can be used to direct choices at opam init automatically (e.g. specific repositories, wrappers, variables, fetch commands, or the external solver). This can be used to override all of opam's OCaml-related settings.

• Simpler library: the OCaml API is completely rewritten and should make it much easier to write external tools and plugins. Existing tools will need to be ported.

• Better error mitigation: Through clever ordering of the shell actions and separation of build and install, most build failures can keep your current installation intact, not resulting in removed packages anymore.

Roll out

You are very welcome to try out the alpha, and report any issues. The repository at opam.ocaml.org will remain in 1.2 format (with a 2.0 mirror at opam.ocaml.org/2.0~dev in sync) until after the release is out, which means the extensions can not be used there yet, but you are welcome to test on local or custom repositories, or package pinnings. The reverse translation (2.0 to 1.2) is planned, to keep supporting 1.2 installations after that date.

The documentation for the new version is available at https://opam.ocaml.org/doc/2.0/. This is still work in progress, so please do ask if anything is unclear.

Interface changes

Commands opam switch and opam list have been rehauled for more consistency and flexibility: the former won't implicitly create new switches unless called with the create subcommand, and opam list now allows to combine filters and finely specify the output format. They may not be fully backwards compatible, so please check your scripts.

Most other commands have also seen fixes or improvements. For example, opam doesn't forget about your set of installed packages on the first error, and the new opam install --restore can be used to reinstall your selection after a failed upgrade.

Repository changes

While users of opam 1.2 should feel at home with the changes, the 2.0 repository and package formats are not compatible. Indeed, the move of the compilers to standard packages implies some conversions, and updates to the relationships between packages and their compiler. For example, package constraints like

available: [ ocaml-version >= "4.02" ]

are now written as normal package dependencies:

depends: [ "ocaml" {>= "4.02"} ]

To make the transition easier,

• upgrade of a custom repository is simply a matter of running opam-admin upgrade-format at its root;
• the official repository at opam.ocaml.org already has a 2.0 mirror, to which you will be automatically redirected;
• packages definition are automatically converted when you pin a package.

Note that the ocaml package on the official repository is actually a wrapper that depends on one of ocaml-base-compiler, ocaml-system or ocaml-variants, which contain the different flavours of the actual compiler. It is expected that it may only get picked up when requested by package dependencies.

Package format changes

The opam package definition format is very similar to before, but there are quite a few extensions and some changes:

• it is now mandatory to separate the build: and install: steps (this allows tracking of installed files, better error recovery, and some optional security features);
• the url and description can now optionally be included in the opam file using the section url {} and fields synopsis: and description:;
• it is now possible to have dependencies toggled by globally-defined opam variables (e.g. for a dependency needed on some OS only), or even rely on the package information (e.g. have a dependency at the same version);
• the new setenv: field allows packages to export updates to environment variables;
• custom fields x-foo: can be used for extensions and external tools;
• allow """ delimiters around unescaped strings
• & is now parsed with higher priority than |
• field ocaml-version: can no longer be used
• the remove: field should not be used anymore for simple cases (just removing files)

Let's go then -- how to try it ?

First, be aware that you'll be prompted to update your ~/.opam to 2.0 format before anything else, so if you value it, make a backup. Or just export OPAMROOT to test the alpha on a temporary opam root.

Packages for opam 2.0 are already in the opam repository, so if you have a working opam installation of opam (at least 1.2.1), you can bootstrap as easily as:

opam install opam-devel

This doesn't install the new opam to your PATH within the current opam root for obvious reasons, so you can manually install it as e.g. "opam2" using:

sudo cp $(opam config var "opam-devel:lib")/opam /usr/local/bin/opam2

You can otherwise install as usual:

• Using pre-built binaries (available for OSX and Linux x86, x86_64, armhf) and our install script:

  wget https://raw.github.com/ocaml/opam/2.0-alpha4-devel/shell/opam_installer.sh -O - | sh -s /usr/local/bin

  Equivalently, pick your version and download it to your PATH;

• Building from our inclusive source tarball: download here and build using ./configure && make lib-ext && make && make install if you have OCaml >= 4.01 already available, make cold && make install otherwise;

• Or from source, following the included instructions from the README. Some files have been moved around, so if your build fails after you updated an existing git clone, try to clean it up (git clean -fdx).

It has only been 18 months since the first release of OPAM, but it is already difficult to remember a time when we did OCaml development without it. OPAM has helped bring together much of the open-source code in the OCaml community under a single umbrella, making it easier to discover, depend on, and maintain OCaml applications and libraries. We have seen steady growth in the number of new packages, updates to existing code, and a diverse group of contributors.

OPAM has turned out to be more than just another package manager. It is also increasingly central to the demanding workflow of industrial OCaml development, since it supports multiple simultaneous (patched) compiler installations, sophisticated package version constraints that ensure statically-typed code can be recompiled without conflict, and a distributed workflow that integrates seamlessly with Git, Mercurial or Darcs version control. OPAM tracks multiple revisions of a single package, thereby letting packages rely on older interfaces if they need to for long-term support. It also supports multiple package repositories, letting users blend the global stable package set with their internal revisions, or building completely isolated package universes for closed-source products.

Since its initial release, we have been learning from the extensive feedback from our users about how they use these features as part of their day-to-day workflows. Larger projects like XenAPI, the Ocsigen web suite, and the Mirage OS publish OPAM remotes that build their particular software suites. Complex applications such as the Pfff static analysis tool and Hack language from Facebook, the Frenetic SDN language and the Arakoon distributed key store have all appeared alongside these libraries. Jane Street pushes regular releases of their production Core/Async suite every couple of weeks.

One pleasant side-effect of the growing package database has been the contribution of tools from the community that make the day-to-day use of OCaml easier. These include the utop interactive toplevel, the IOCaml browser notebook, and the Merlin IDE extension. While these tools are an essential first step, there's still some distance to go to make the OCaml development experience feel fully integrated and polished.

Today, we are kicking off the next phase of evolution of OPAM and starting the journey towards building an OCaml Platform that combines the OCaml compiler toolchain with a coherent workflow for build, documentation, testing and IDE integration. As always with OPAM, this effort has been a collaborative effort, coordinated by the OCaml Labs group in Cambridge and OCamlPro in France. The OCaml Platform builds heavily on OPAM, since it forms the substrate that pulls together the tools and facilitates a consistent development workflow. We've therefore created this blog on opam.ocaml.org to chart its progress, announce major milestones, and eventually become a community repository of all significant activity.

Major points:

• OPAM 1.2 beta available: Firstly, we're announcing the availability of the OPAM 1.2 beta, which includes a number of new features, hundreds of bug fixes, and pretty new colours in the CLI. We really need your feedback to ensure a polished release, so please do read the release notes below.

• In the coming weeks, we will provide an overview of what the OCaml Platform is (and is not), and describe an example workflow that the Platform can enable.

• Feedback: If you have questions or comments as you read these posts, then please do join the platform@lists.ocaml.org and make them known to us.

Releasing the OPAM 1.2 beta4

We are proud to announce the latest beta of OPAM 1.2. It comes packed with new features, stability and usability improvements. Here the highlights.

Binary RPMs and DEBs!

We now have binary packages available for Fedora 19/20, CentOS 6/7, RHEL7, Debian Wheezy and Ubuntu! You can see the full set at the OpenSUSE Builder site and download instructions for your particular platform.

An OPAM binary installation doesn't need OCaml to be installed on the system, so you can initialize a fresh, modern version of OCaml on older systems without needing it to be packaged there. On CentOS 6 for example:

cd /etc/yum.repos.d/
wget http://download.opensuse.org/repositories/home:ocaml/CentOS_6/home:ocaml.repo
yum install opam
opam init --comp=4.01.0

Simpler user workflow

For this version, we focused on improving the user interface and workflow. OPAM is a complex piece of software that needs to handle complex development situations. This implies things might go wrong, which is precisely when good support and error messages are essential. OPAM 1.2 has much improved stability and error handling: fewer errors and more helpful messages plus better state backups when they happen.

In particular, a clear and meaningful explanation is extracted from the solver whenever you are attempting an impossible action (unavailable package, conflicts, etc.):

$ opam install mirage-www=0.3.0
The following dependencies couldn't be met:
  - mirage-www -> cstruct < 0.6.0
  - mirage-www -> mirage-fs >= 0.4.0 -> cstruct >= 0.6.0
Your request can't be satisfied:
  - Conflicting version constraints for cstruct

This sets OPAM ahead of many other package managers in terms of user-friendliness. Since this is made possible using the tools from irill (which are also used for Debian), we hope that this work will find its way into other package managers. The extra analyses in the package solver interface are used to improve the health of the central package repository, via the OPAM Weather service.

And in case stuff does go wrong, we added the opam upgrade --fixup command that will get you back to the closest clean state.

The command-line interface is also more detailed and convenient, polishing and documenting the rough areas. Just run opam <subcommand> --help to see the manual page for the below features.

• More expressive queries based on dependencies.

  $ opam list --depends-on cow --rec
  # Available packages recursively depending on cow.0.10.0 for 4.01.0:
  cowabloga   0.0.7  Simple static blogging support.
  iocaml      0.4.4  A webserver for iocaml-kernel and iocamljs-kernel.
  mirage-www  1.2.0  Mirage website (written in Mirage)
  opam2web    1.3.1 (pinned)  A tool to generate a website from an OPAM repository
  opium       0.9.1  Sinatra like web toolkit based on Async + Cohttp
  stone       0.3.2  Simple static website generator, useful for a portfolio or documentation pages
  

• Check on existing opam files to base new packages from.

  $ opam show cow --raw
  opam-version: "1"
  name: "cow"
  version: "0.10.0"
  [...]
  

• Clone the source code for any OPAM package to modify or browse the interfaces.

  $ opam source cow
  Downloading archive of cow.0.10.0...
  [...]
  $ cd cow.0.10.0
  

We've also improved the general speed of the tool to cope with the much bigger size of the central repository, which will be of importance for people building on low-power ARM machines, and added a mechanism that will let you install newer releases of OPAM directly from OPAM if you choose so.

Yet more control for the packagers

Packaging new libraries has been made as straight-forward as possible. Here is a quick overview, you may also want to check the OPAM 1.2 pinning post.

opam pin add <name> <sourcedir>

will generate a new package on the fly by detecting the presence of an opam file within the source repository itself. We'll do a followup post next week with more details of this extended opam pin workflow.

The package description format has also been extended with some new fields:

• bug-reports: and dev-repo: add useful URLs
• install: allows build and install commands to be split,
• flags: is an entry point for several extensions that can affect your package.

Packagers can limit dependencies in scope by adding one of the keywords build, test or doc in front of their constraints:

depends: [
  "ocamlfind" {build & >= 1.4.0}
  "ounit" {test}
]

Here you don't specifically require ocamlfind at runtime, so changing it won't trigger recompilation of your package. ounit is marked as only required for the package's build-test: target, i.e. when installing with opam install -t. This will reduce the amount of (re)compilation required in day-to-day use.

We've also made optional dependencies more consistent by removing version constraints from the depopts: field: their meaning was unclear and confusing. The conflicts field is used to indicate versions of the optional dependencies that are incompatible with your package to remove all ambiguity:

depopts: [ "async" {>= "109.15.00"} & "async_ssl" {>= "111.06.00"} ]

becomes:

depopts: [ "async" "async_ssl" ]
conflicts: [ "async" {< "109.15.00"}
             "async_ssl" {< "111.06.00"} ]

There is an upcoming features field that will give more flexibility in a clearer and consistent way for such complex cases.

Easier to package and install

Efforts were made on the build of OPAM itself as well to make it as easy as possible to compile, bootstrap or install. There is no more dependency on camlp4 (which has been moved out of the core distribution in OCaml 4.02.0), and the build process is more conventional (get the source, run ./configure, make lib-ext to get the few internal dependencies, make and make install). Packagers can use make cold to build OPAM with a locally compiled version of OCaml (useful for platforms where it isn't packaged), and also use make download-ext to store all the external archives within the source tree (for automated builds which forbid external net access).

The whole documentation has been rewritten as well, to be better focused and easier to browse. Please leave any feedback or changes on the documentation on the issue tracker.

Try it out !

The public beta of OPAM 1.2 is just out. You're welcome to give it a try and give us feedback before we roll out the release!

We'd be most interested on feedback on how easily you can work with the new pinning features, on how the new metadata works for you... and on any errors you may trigger that aren't followed by informative messages or clean behaviour.

If you are hosting a repository, the administration scripts may help you quickly update all your packages to benefit from the new features.

OPAM 1.1.0 is ready, and we are shipping a release candidate for packagers and all interested to try it out.

This version features several bug-fixes over the September beta release, and quite a few stability and usability improvements. Thanks to all beta-testers who have taken the time to file reports, and helped a lot tackling the remaining issues.

Repository change to opam.ocaml.org

This release is synchronized with the migration of the main repository from ocamlpro.com to ocaml.org. A redirection has been put in place, so that all up-to-date installation of OPAM should be redirected seamlessly. OPAM 1.0 instances will stay on the old repository, so that they won't be broken by incompatible package updates.

We are very happy to see the impressive amount of contributions to the OPAM repository, and this change, together with the licensing of all metadata under CC0 (almost pubic domain), guarantees that these efforts belong to the community.

If you are upgrading from 1.0

The internal state will need to be upgraded at the first run of OPAM 1.1.0. THIS PROCESS CANNOT BE REVERTED. We have tried hard to make it fault- resistant, but failures might happen. In case you have precious data in your ~/.opam folder, it is advised to backup that folder before you upgrade to 1.1.0.

Installing

Using the binary installer:

• download and run http://www.ocamlpro.com/pub/opam_installer.sh

You can also get the new version either from Anil's unstable PPA: add-apt-repository ppa:avsm/ppa-testing apt-get update sudo apt-get install opam

or build it from sources at :

• http://www.ocamlpro.com/pub/opam-full-1.1.0.tar.gz
• https://github.com/OCamlPro/opam/releases/tag/1.1.0-RC

We are very happy to announce the beta release of OPAM version 1.1.0!

OPAM is a source-based package manager for OCaml. It supports multiple simultaneous compiler installations, flexible package constraints, and a Git-friendly development workflow which. OPAM is edited and maintained by OCamlPro, with continuous support from OCamlLabs and the community at large (including its main industrial users such as Jane-Street and Citrix).

Since its first official release last March, we have fixed many bugs and added lots of new features and stability improvements. New features go from more metadata to the package and compiler descriptions, to improved package pin workflow, through a much faster update algorithm. The full changeset is included below.

We are also delighted to see the growing number of contributions from the community to both OPAM itself (35 contributors) and to its metadata repository (100+ contributors, 500+ unique packages, 1500+ packages). It is really great to also see alternative metadata repositories appearing in the wild (see for instance the repositories for Android, Windows and so on). To be sure that the community efforts will continue to benefit to everyone and to underline our committment to OPAM, we are rehousing it at https://opam.ocaml.org and switching the license to CC0 (see issue #955, where 85 people are commenting on the thread).

The binary installer has been updated for OSX and x86_64:

• http://www.ocamlpro.com/pub/opam_installer.sh

You can also get the new version either from Anil's unstable PPA: add-apt-repository ppa:avsm/ppa-testing apt-get update sudo apt-get install opam

or build it from sources at :

• http://www.ocamlpro.com/pub/opam-full-1.1.0-beta.tar.gz
• https://github.com/OCamlPro/opam/releases/tag/1.1.0-beta

NOTE: If you upgrade from OPAM 1.0, the first time you will run the new opam binary it will upgrade its internal state in an incompatible way: THIS PROCESS CANNOT BE REVERTED. We have tried hard to make this process fault-resistant, but failures might happen. In case you have precious data in your ~/.opam folder, it is advised to backup that folder before you upgrade to 1.1.