These are commands that will likely be useful during development.

General: ./scripts/test.sh compiles and builds the Haskell code and runs all tests. Recommended that you run this before pushing any code to a branch that others might be working on.

Disclaimer If you have trouble getting started, please get in touch via Discord so we can help. If you have any fixes to the process, please send us a PR!

To get cracking with Unison:

1. Install stack.
2. Build the project with stack build. This builds all executables.
3. (Optional) Run ./dev-ui-install.hs to fetch the latest release of the codebase UI. If you don't care about running the codebase UI locally you can ignore this step.
4. After building do stack exec unison to will initialize a codebase in your home directory (in ~/.unison). This only needs to be done once. (Alternatively, you can use stack exec -- unison -C <other dir> to create a codebase in <other dir>
5. stack exec unison starts Unison and watches for .u file changes in the current directory. If you want to run it in a different directory, just add unison to your PATH, after finding it with stack exec which unison.

On startup, Unison prints a url for the codebase UI. If you did step 3 above, then visiting that URL in a browser will give you a nice interface to your codebase.

We use 0.5.0.1 of Ormolu and CI will add an extra commit, if needed, to autoformat your code.

Also note that you can always wrap a comment around some code you don't want Ormolu to touch, using:

{- ORMOLU_DISABLE -}
dontFormatMe = do blah
                    blah
                  blah
{- ORMOLU_ENABLE -}

• stack test --fast builds and runs most test suites, see below for exceptions to this (e.g. transcript tests).

Most test suites support selecting a specific test to run by passing a prefix as a test argument:

• stack test unison-parser-typechecker --fast --test-arguments my-test-prefix builds and runs most test suites, see below for exceptions to this (e.g. transcript tests).

Some tests are executables instead:

• stack exec transcripts runs the transcripts-related integration tests, found in unison-src/transcripts. You can add more tests to this directory.
• stack exec transcripts -- prefix-of-filename runs only transcript tests with a matching filename prefix.
• stack exec cli-integration-tests runs the additional integration tests for cli. These tests are not triggered by tests or transcripts.
• stack exec unison -- transcript unison-src/transcripts-round-trip/main.md runs the pretty-printing round trip tests
• stack exec unison -- transcript unison-src/transcripts-manual/benchmarks.md runs the benchmark suite. Output goes in unison-src/transcripts-manual/benchmarks/output.txt.

Do:

stack build --fast --test --bench --no-run-tests --no-run-benchmarks

Do:

stack build --profile unison-parser-typechecker

Again you can leave off the flag. To run an executable with profiling enabled, do:

stack exec -- <executable-name>  RTS -p

That will generate a <executable-name>.prof plain text file with profiling data. More info on profiling.

Unison can also be built/installed with cabal. You'll need the same ghc used by stack.yaml to successfully build its dependencies. The provided project file is also in contrib/ so you'll need to specify its location on the command line.

• To build all projects use

  cabal v2-build --project-file=contrib/cabal.project all

• Tests can be run with e.g.

  cabal v2-test --project-file=contrib/cabal.project all

• The executable can be installed with

  cabal v2-install --project-file=contrib/cabal.project unison

• The install directory can be modified with the option --installdir: ...

• Take in account that if you want to load the project in haskell-language-server using cabal instead stack you will need:

  • Copy or link ./contrib/cabal.project to ./cabal.project
  • Delete or rename the existing ./hie.yaml. The default behaviour without hie.yaml works with cabal.

This codebase uses symlinks as a workaround for some inconveniences in the here package. Support for symlinks in Windows is relatively new, and isn't enabled by default. As a result, your cloned copy of the code probably won't build.

First you'll need to enable "Developer Mode" in your Windows settings.

See https://consumer.huawei.com/en/support/content/en-us15863140/

Then you'll need to enable symlink support in your git configuration, e.g.

git config core.symlinks true

And then ask git to fix up your symlinks with git checkout .

More context at: https://stackoverflow.com/a/59761201/310162

Stack doesn't work deterministically in Windows due to mismatched expectations about how file deletion works. If you get this error, you can just retry the build and it will probably make more progress than the last time.

NB: It is important that the Unison Nix cache is trusted when building, otherwise you will likely end up building hundreds of packages, including GHC itself.

The recommended way to do this is to add the public key and URL for the cache to your system’s Nix configuration. /etc/nix/nix.conf should have lines similar to

trusted-public-keys = unison.cachix.org-1:i1DUFkisRPVOyLp/vblDsbsObmyCviq/zs6eRuzth3k=
trusted-substituters = https://unison.cachix.org

these lines could be prefixed with extra- and they may have additional entries besides the ones for our cache.

This command should work if you don’t want to edit the file manually:

sudo sh -c 'echo "extra-trusted-public-keys = unison.cachix.org-1:i1DUFkisRPVOyLp/vblDsbsObmyCviq/zs6eRuzth3k=
extra-trusted-substituters = https://unison.cachix.org" >>/etc/nix/nix.conf'

After updating /etc/nix/nix.conf, you need to restart the Nix daemon. To do this on

• Ubuntu: sudo systemctl restart nix-daemon
• MacOS:

  sudo launchctl unload /Library/LaunchDaemons/org.nixos.nix-daemon.plist
  sudo launchctl load /Library/LaunchDaemons/org.nixos.nix-daemon.plist

If you use NixOS, you may instead add this via your configuration.nix with

nix.settings.trusted-public-keys = ["unison.cachix.org-1:i1DUFkisRPVOyLp/vblDsbsObmyCviq/zs6eRuzth3k="];
nix.settings.trusted-substituters = ["https://unison.cachix.org"];

and run sudo nixos-rebuild switch afterward.

It is not recommended to add your user to trusted-users. This can make enabling flake configurations simpler (like the Unison Nix cache here), but it is equivalent to giving that user root access (without need for sudo).

nix build

This is specified with the normal <package>:<component-type>:<component-name> triple.

Some examples:

nix build '.#component-unison-cli:lib:unison-cli'
nix build '.#component-unison-syntax:test:syntax-tests'
nix build '.#component-unison-cli:exe:transcripts'

This gets you into a development environment with the preferred versions of the compiler and other development tools. These include:

• ghc
• stack
• ormolu
• haskell-language-server

nix develop

This gets you into a development environment with the preferred versions of the compiler and other development tools. Additionally, all non-local haskell dependencies (including profiling dependencies) are provided in the nix shell.

nix develop '.#cabal-local'

This gets you into a development environment with the preferred versions of the compiler and other development tools. Additionally, all haskell dependencies of this package are provided by the nix shell (including profiling dependencies).

nix develop '.#cabal-<package-name>'

for example:

nix develop '.#cabal-unison-cli'

or

nix develop '.#cabal-unison-parser-typechecker'

This is useful if you wanted to profile a package. For example, if you want to profile unison-cli-main:exe:unison then you could get into one of these shells, cd into its directory, then run the program with profiling.

nix develop '.#cabal-unison-parser-typechecker'
cd unison-cli
cabal run --enable-profiling unison-cli-main:exe:unison --  RTS -p

See the readme.