A tool to help with fetching Cabal packages from Hackage and importing them as packages into cabal2bazel.
Usage: cabal2bazel --fetch
Examples: cabal2bazel --fetch binary cabal2bazel --fetch binary-0.5.0.2 cabal2bazel --recursive --fetch lens
The process for installing third-party Haskell packages is specified at: https://opensource.google.com/docs/thirdparty/haskell/ cabal2bazel does not (yet) capture all the subtleties of this process, and is no substitute for code review. But it will automate the bulk of chores, including:
- fetching the Cabal package;
- unpacking it into an appropriate directory;
- ensuring the license file is in the expected location;
- generating a BUILD file with suitable rules.
- if --recursive is specified, traversing graph of all dependencies of selected package and importing all of them.
cabal2bazel attempts to map the dependencies of a Cabal library or executable to the 'deps' attribute of the resulting Bazel target.
Things that still need manual attention include:
- optimization modes need to be removed from ghcopts, because Bazel chooses them itself;
- cabal2bazel adds '-Wwarn' to all rules' ghcopts; this might not be desired;
- correct choice of license attributes should be checked;
- generated dependencies might need to be adjusted to point to specific versions of the packages depended upon.
NOTE: You will need an appropriate version of 'cabal' to be available on your path; cabal2bazel uses it for downloading and unpacking packages.
NOTE: Sometimes it is necessary to edit the cabal file and re-run cabal2bazel. In such cases rerun cabal2bazel as follows to resume installation:
cabal2bazel --wire-up
Example: cabal2bazel --wire-up //third_party/haskell/binary/v0_5_0_2