Top-level CONTRIBUTING.md file

Author: LaurentRDC

CONTRIBUTING.md

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+# Cloud Haskell contributor guidelines
+
+## Building
+
+After cloning, you should be able to build all packages in this repository like so:
+
+```
+$ cabal build all
+```
+
+You can also build a specific package like so:
+
+```
+cabal build <some-package>
+```
+
+You can have more control over the behavior of `cabal` by configuring, first. For example, if you want to disable optimizations for faster compilation:
+
+```
+$ cabal configure --disable-optimization
+$ cabal build all
+```
+
+The allowed arguments for `cabal configure` are [documented here](https://cabal.readthedocs.io/en/stable/cabal-project-description-file.html#global-configuration-options).
+
+Tests for all packages can be run with:
+
+```
+$ cabal test all
+```
+
+or again, you can test a specific package `<some-package>` using:
+
+```
+$ cabal test <some-package>
+```
+
+### Building with specific dependencies
+
+Often, we want to build a package with a specific version of a dependency, for testing or debugging purposes. In this case, recall that you can always constrain cabal using the `--constraint` flag. For example, if I want to build `distributed-process-async` with `async==2.2.5`:
+
+```
+$ cabal build distributed-process-async --constraint="async==2.2.5"
+```
+
+## Contributing changes upstream
+
+To contribute changes, you first need a fork. First, fork the `distributed-process` repository following the [instructions here](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/fork-a-repo).
+
+Then publish branches:
+
+```
+$ cabal test all        # Check that everything works before proceeding.
+$ git push --set-upstream <username> <branch-name>
+```
+
+Then you can [create a pull-request](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request) to contribute changes back to `distributed-process`.