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We are happy to announce the alpha release of opam 2.2.0. It contains numerous
fixes, enhancements, and updates; including much-improved Windows support,
addressing one of the most important pain points identified by the OCaml
community.
You can view the full list of changes in the release
note.
This alpha release is a significant milestone, brought together by Raja Boujbel
after years of work from the opam dev team (Raja Boujbel, David Allsopp, Kate
Deplaix, Louis Gesbert, in a united OCamlPro/Tarides collaboration) with the
help of many community contributors. We also thank Jane Street for their
continued sponsorship.
This version is an alpha, so we invite users to test it to spot previously
unnoticed bugs and work towards a stable release.
Windows Support
Opam 2.2 comes with native Windows compatibility. You can now use opam from
your preferred Windows terminal! We rely on the Cygwin
UNIX-like environment for Windows as a compatibility layer, but it is possible
for a package to generate native executables.
The main opam repository is not Windows compatible at the moment, but existing
work on a compatible
repository (originally
from @fdopen) and 32/64 bit mingw-w64
packages (by
@dra27) is in the process of being merged. Before
the final release, we expect it to be possible to run opam init and use the
main opam-repository for Windows.
How to Test opam on Windows
This alpha requires a preexisting Cygwin installation. Support for full
management of a local Cygwin environment inside of opam (so that it's as
transparent as possible) is queued already and should be available in
2.2.0~alpha2 as the default option.
- Check that you have all dependencies installed:
autoconf, make, patch, curl- MinGW compilers:
mingw64-x86_64-gcc-g++, mingw64-i686-gcc-g++
- Or if you want to use the MSVC port of OCaml, you'll need to install Visual Studio or Visual Studio Build Tools
- Download & extract the opam archive
- In the directory launch
make cold
- A coffee later, you now have an opam executable!
- Start your preferred Windows terminal (cmd or PowerShell), and initialise opam with the Windows sunset repository:
opam init https://github.com/ocaml-opam/opam-repository-mingw
From here, you can try to install sunset
repository
packages. If any bug is found, please submit an
issue.
It will help opam repository maintainers to add Windows repository packages
into the main repository.
Hint: if you use the MinGW compiler, don't forget to add to your PATH the
path to libc dlls (usually
C:\cygwin64\usr\x86_64-w64-mingw32\sys-root\mingw\bin). Or compile opam with
make cold CONFIGURE_ARGS=--with-private-runtime, and if you change opam
location, don't forget to copy Opam.Runtime.amd64 (or Opam.Runtime.i386)
with it.
Recursive Pin
When installing or pinning a package using opam install or opam pin, opam
normally only looks for opam files at the root of the installed package. With
recursive pinning, you can now instruct opam to also look for .opam files in
subdirectories, while maintaining the correct relationship between the .opam
files and the package root for versioning and build purposes.
Recursive pinning is used with the following options to opam pin and opam install:
- With
--recursive, opam will look for .opam files recursively in all subdirectories.
- With
--subpath <path>, opam will only look for .opam files in the subdirectory <path>.
The two options can be combined: for instance, if your opam packages are stored
as a deep hierarchy in the mylib subdirectory of your project, give opam pin . --recursive --subpath mylib a try!
You can use these options with opam pin, opam install, and opam remove.
$ tree .
.
├── ba
│ └── z
│ └── z.opam
├── bar
│ └── bar.opam
└── foo.opam
$ opam pin . --subpath ba/z --no-action
Package z does not exist, create as a NEW package? [y/n] y
z is now subpath-pinned to directory /ba/z in git+file:///tmp/recpin#master (version 0.1)
$ opam pin --recursive . --no-action
This will pin the following packages: foo, z, bar. Continue? [y/n] y
foo is now pinned to git+file:///tmp/recpin#master (version 0.1)
Package z does not exist, create as a NEW package? [y/n] y
z is now subpath-pinned to directory /ba/z in git+file:///tmp/recpin#master (version 0.1)
Package bar does not exist, create as a NEW package? [y/n] y
bar is now subpath-pinned to directory /bar in file:///tmp/recpin (version 0.1)
$ opam pin
bar.0.1 (uninstalled) rsync directory /bar in file:///tmp/recpin
foo.0.1 (uninstalled) git git+file:///tmp/recpin#master
z.0.1 (uninstalled) git directory /ba/z in git+file:///tmp/recpin#master
$ opam pin . --recursive --subpath ba/ --no-action
Package z does not exist, create as a NEW package? [y/n] y
z is now subpath-pinned to directory /ba/z in git+file:///tmp/recpin#master (version 0.1)
Tree View
opam tree shows packages and their dependencies with a tree view. It is very
helpful to determine which packages bring which dependencies in your installed
switch.
$ opam tree cppo
cppo.1.6.9
├── base-unix.base
├── dune.3.8.2 (>= 1.10)
│ ├── base-threads.base
│ ├── base-unix.base [*]
│ └── ocaml.4.14.1 (>= 4.08)
│ ├── ocaml-base-compiler.4.14.1 (>= 4.14.1~ & < 4.14.2~)
│ └── ocaml-config.2 (>= 2)
│ └── ocaml-base-compiler.4.14.1 (>= 4.12.0~) [*]
└── ocaml.4.14.1 (>= 4.02.3) [*]
It can also display a reverse-dependency tree (through opam why, which is an
alias to opam tree --rev-deps). This is useful to examine how dependency
versions get constrained.
$ opam why cmdliner
cmdliner.1.2.0
├── (>= 1.1.0) b0.0.0.5
│ └── (= 0.0.5) odig.0.0.9
├── (>= 1.1.0) ocp-browser.1.3.4
├── (>= 1.0.0) ocp-indent.1.8.1
│ └── (>= 1.4.2) ocp-index.1.3.4
│ └── (= version) ocp-browser.1.3.4 [*]
├── (>= 1.1.0) ocp-index.1.3.4 [*]
├── (>= 1.1.0) odig.0.0.9 [*]
├── (>= 1.0.0) odoc.2.2.0
│ └── (>= 2.0.0) odig.0.0.9 [*]
├── (>= 1.1.0) opam-client.2.2.0~alpha
│ ├── (= version) opam.2.2.0~alpha
│ └── (= version) opam-devel.2.2.0~alpha
├── (>= 1.1.0) opam-devel.2.2.0~alpha [*]
├── (>= 0.9.8) opam-installer.2.2.0~alpha
└── user-setup.0.7
Special thanks to @cannorin for contributing this feature.
Recommended Development Tools
There is now a way for a project maintainer to share their project development
tools: the with-dev-setup dependency flag. It is used in the same way as
with-doc and with-test: by adding a {with-dev-setup} filter after a
dependency. It will be ignored when installing normally, but it's pulled in when the
package is explicitely installed with the --with-dev-setup flag specified on
the command line. The variable is also resolved in the post-messages: field
to allow maintainers to share more informations about that setup.
This is typically useful for tools that are required for bootstrapping or
regenerating artifacts.
For example
opam-version: "2.0"
depends: [
"ocaml"
"dune"
"ocp-indent" {with-dev-setup}
]
build: [make]
install: [make "install"]
post-messages:
[ "Thanks for installing the package"
"and its tool dependencies too, it will help for your futur PRs" {with-dev-setup} ]
Software Heritage Binding
Software Heritage is a project that aims to
archive all software source code in existence. This is done by collecting
source code with a loader that uploads software source code to the Software
Heritage distributed infrastructure. From there, any project/version is
available via the search webpage and
via a unique identifier called the
SWHID.
Some OCaml source code is already
archived, and
the main opam and Coq repository packages are continuously uploaded.
Opam now integrates a fallback to Software Heritage archive retrieval, based on
SWHID. If an SWHID URL is present in an opam file, the fallback can be
activated.
To keep backwards compatibility of opam files, we added a specific Software
Heritage URL syntax to the url.mirrors: field, which is used to specify
mirrors of the main URL. Opam 2.2.+ understands this specific syntax as a
Software Heritage fallback URL: https://swhid.opam.ocaml.org/<SWHID>.
url {
src: "https://faili.ng/url.tar.gz"
checksum: "sha512=e2146c1d7f53679fd22df66c9061b5ae4f8505b749513eedc67f3c304f297d92e54f5028f40fb5412d32c7d7db92592eacb183128d2b6b81d10ea716b7496eba"
mirrors: [
"https//failli.ng/mirror.tar.gz"
"https://swhid.opam.ocaml.org/swh:1:dir:9f2be900491e1dabfc027848204ae01aa88fc71d"
]
}
To add a Software Heritage fallback URL to your package, use the
swhid library. Specifically the
Compute.directory_identifier_deep
function:
- Download opam package archive
- Extract the archive
- Compute SWHID with
Compute.directory_identifier_deep. You can use this oneliner in the directory:
ocaml -e '#use "topfind";; #require "digestif.ocaml";; #require "swhid";; Swhid_core.Object.pp Format.std_formatter (Result.get_ok (Swhid.Compute.directory_identifier_deep "."))'
Special thanks to @zapashcanon for collaborating on this feature.
Formula (Experimental)
It is now possible to leverage the full expressivity of package dependency
formulas from the command line during switch creation and package operations.
It is possible to create a switch using a formula. For example, with
ocaml-variant or ocaml-system, excluding ocaml-base-compiler:
opam switch create ocaml --formula '"ocaml-variants" {>= "4.14.1"} | "ocaml-system"'
This syntax is brought to install commands. For example, while installing a
package, let's say genet, you can specify that you want to install either
conf-mariadb & mariadb or conf-postgresql:
opam install genet --formula '["mysql" ("conf-mariadb" & "mariadb" | "conf-postgresql")]'
New Options
Here are several of new options (possibly scripts breaking changes are marked with ✘):
-
opam pin --current to fix a package to its current state (disabling pending
reinstallations or removals from the repository). The installed package will
be pinned with the opam file that is stored in opam internal state, the one
that is currently installed.
-
opam pin remove --all to remove all the pinned packages from a switch.
-
opam pin remove pkg.version now removes the pins on pinned pkg.version.
-
opam exec --no-switch to remove opam environment from launched command.
$ export FOOVAR=env
$ opam show foo --field setenv
FOOVAR = "package"
$ opam exec -- env | grep "OPAM_SWITCH\|FOO"
FOOVAR=package
OPAM_SWITCH_PREFIX=~/.opam/env
$ opam exec --no-switch -- env | grep "OPAM_SWITCH\|FOO"
FOOVAR=env
-
opam source --no-switch to allow downloading package sources without having
an installed switch (instead of failing).
-
opam clean --untracked to remove untracked files interactively remaining
from previous packages removal.
-
opam switch -, inspired from git switch -, that goes back to the previously
selected global switch.
-
opam admin add-constraint <cst> --packages pkg1,pkg2,pkg3 to select
a subset of packages to apply constraints.
-
✘ Change --base into --invariant. opam switch compiler column now
contains installed packages that verifies invariant formula, and empty
synopsis shows switch invariant.
$ opam switch create inv --formula '["ocaml" {>= "4.14.1"} "dune"]'
$ opam switch invariant
["ocaml" {>= "4.14.1"} "dune"]
$ opam list --invariant
# Packages matching: invariant
# Name # Installed # Synopsis
dune 3.8.2 Fast, portable, and opinionated build system
ocaml 5.0.0 The OCaml compiler (virtual package)
$ opam switch list
# switch compiler description
→ inv ocaml-base-compiler.5.0.0,ocaml-options-vanilla.1 ocaml >= 4.14.1 & dune
Try It!
In case you plan a possible rollback, you may want to first backup your
~/.opam directory.
The upgrade instructions are unchanged:
- From binaries: run
bash -c "sh <(curl -fsSL https://raw.githubusercontent.com/ocaml/opam/master/shell/install.sh) --version 2.2.0~alpha"
Or download manually from the Github "Releases" page to your PATH.
- From source, manually: see the instructions in the README.
Then run:
opam init --reinit -ni
Please report any issues to the bug-tracker.
Thanks for trying this new release out, and we're hoping you will enjoy the new features!