Dune - A composable build system
Dune is a build system designed for OCaml/Reason projects only. It focuses on providing the user with a consistent experience and takes care of most of the low-level details of OCaml compilation. All you have to do is provide a description of your project and dune will do the rest.
The scheme it implements is inspired from the one used inside Jane Street and adapted to the open source world. It has matured over a long time and is used daily by hundreds of developers, which means that it is highly tested and productive.
The example directory contains examples of projects using dune.
Dune reads project metadata from
dune files, which are either static files in a simple S-expression syntax or OCaml scripts. It uses this information to setup build rules, generate configuration files for development tools such as merlin, handle installation, etc...
Dune itself is fast, has very low overhead and supports parallel builds on all platforms. It has no system dependencies: all you need to build dune and packages using dune is OCaml. You don't need
bash as long as the packages themselves don't use
In particular, one can install OCaml on Windows with a binary installer and then use only the Windows Console to build dune and packages using dune.
Take n repositories that use dune, arrange them in any way on the file system and the result is still a single repository that dune knows how to build at once.
This make simultaneous development on multiple packages trivial.
Gracefully handles multi-package repositories
Dune knows how to handle repositories containing several packages. When building via opam, it is able to correctly use libraries that were previously installed even if they are already present in the source tree.
The magic invocation is:
$ dune build --only-packages <package-name> @install
Building against several configurations at once
Dune is able to build a given source code repository against several configurations simultaneously. This helps maintaining packages across several versions of OCaml as you can test them all at once without hassle.
In particular, this makes it easy to handle cross-compilation.
This feature requires opam.
Dune requires OCaml version 4.08.0 to build itself and can build OCaml projects using ocaml 4.02.3 or greater.
The recommended way to install dune is via the opam package manager:
$ opam install dune
If you are new to opam, make sure to run
eval $(opam config env) to make
dune available in your
PATH. The dune binary is self contained and relocatable, so you can safely copy it somewhere else to make it permanently available.
You can also build it manually with:
$ make release $ make install
If you do not have
make, you can do the following:
$ ocaml bootstrap.ml $ ./dune.exe build -p dune --profile dune-bootstrap $ ./dune.exe install dune
The first command builds the
dune.exe binary. The second builds the additional files that are installed by dune, such as the man pages, and the last simply installs all of that on the system.
Note that unless you ran the optional
./configure script, you can simply copy
dune.exe anywhere and it will just work.
dune is fully relocatable and discovers its environment at runtime rather than hard-coding it at compilation time.
If you have questions about dune, you can send an email to firstname.lastname@example.org or open a ticket on GitHub.
Migration from jbuilder
Dune was formerly known as jbuilder. Migration from jbuilder to dune is described in the manual.
Dune is now fairly stable and is used by the majority of packages on opam. Note that dune retains backward compatibility with Jbuilder, and in particular existing Jbuilder projects will continue to be buildable with dune.