2.6 KiB
Hacking on Dune
This section is for people who want to work on Dune itself.
Bootstrap
In order to build itself, Dune uses an OCaml script
(bootstrap.ml) that dumps most of the sources of Dune into a
single boot.ml
file. This file is built using ocamlopt
or ocamlc
and used to build everything else.
Note that we don't include all of the sources in boot.ml. We skip a few parts to speed up the build. In particular:
- vendored libraries are replaced by simpler implementations taken
from
vendor/boot
- a few files in
src
have an alternative version. These alternatives versions are namedXXX.boot.EXT
. For instance:glob_lexer.boot.ml
OCaml compatibility test
Install opam switches for all the entries in the dune-workspace.dev file and run:
$ make all-supported-ocaml-versions
Repository organization
vendor/
contains dependencies of Dune, that have been vendoredplugin/
contains the API given todune
files that are OCaml scriptssrc/
contains the core ofDune
, as a library so that it can be used to implement the Jenga bridge laterbin/
contains the command line interfacedoc/
contains the manual and rules to generate the manual pages
Design
Dune (nee "JBuilder") was initially designed to sort out the public release of Jane Street packages which became incredibly complicated over time. It is still successfully used for this purpose.
One necessary feature to achieve this is the ability to precisely
report the external dependencies necessary to build a given set of
targets without running any command, just by looking at the source
tree. This is used to automatically generate the <package>.opam
files for all Jane Street packages.
To implement this, the build rules are described using a build arrow, which is defined in src/build.mli. In the end it makes the development of the internal rules of Dune very composable and quite pleasant.
To deal with process multiplexing, Dune uses a simplified Lwt/Async-like monad, implemented in src/future.mli.
Code flow
- src/jbuild.mli contains the internal representation
of
dune
files and the parsing code - src/jbuild_load.mli contains the code to scan
a source tree and build the internal database by reading
the
dune
files - src/gen_rules.mli contains all the build rules of Dune
- src/build_system.mli contains a trivial implementation of a Build system. This is what Jenga will provide when implementing the bridge