haskell-project-nix-template

WARNING: when renaming the project, be sure to add sources to control, at least git add, otherwise haskell.nix will not found your cabal file...

Requirements

• Nix installed (https://nixos.org/download.html)
• cachix

substituters = https://cache.nixos.org https://hydra.iohk.io https://iohk.cachix.org https://cache.nixos.org/
trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= iohk.cachix.org-1:DpRUyj7h7V830dp/i6Nti+NEO2/nhblbov/8MW7Rqoo=

• direnv recommended

Please note that loading the shell is way way longer than invoking the nix build because it is providing the dev environment.

Nix build & run

You can use Nix or cabal to build.

# Without nix
cabal run haskell-project-nix-template-exe
# With Nix
nix-build -A project.haskell-project-nix-template.components.exes.haskell-project-nix-template-exe

Git hooks

Some git hooks has been configured to run automatically over your commit changes.

For now it is composed of ormolu and nixpkgs-fmt.

Formatting

We are using here ormolu but you can switch to stylish haskell if you want without too much fuzz.

An extra alias is also available from shell: ormolu-src which will run over the whole project

Testing

We used hedgehog for property base test, and hunit, tasty for the rest.

Another convention it that, in all Spec file, the module we want to test must be qualified imported as SUT (Subject/System Under Test) for better and faster use.

Stan

Stan is a Haskell STatic ANalysis tool: https://github.com/kowainik/stan

stan --hiedir=.hie-files report

You also have a convenient alias to do that

stan-hie

Weeder

Broken for now as it detects everything as non used.

Guess: try to use flake to build it from repository.

CI

github workflow example can be found in .github/workflows/

Issue

The shell, for the first time is very very long, and if you changes some things in the shell.nix, like mentioned above it can trigger a full Nix rebuild (like ghc!). Still a direct nix-build is very fast (10s something like that depending on your machine).