Effekt Template

Warning

This is a work-in-progress, feel free to contribute!

This template provides a starting point for Effekt projects.

Table of contents

• First steps
• Useful commands
  • Effekt commands
  • Nix-related commands
• Example projects
• Repository structure
• CI

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First steps

After using this template, follow these steps to set up your project:

1. Set up your development environment:

   • Clone this repository locally.
   • Open it in VSCode.
   • Install the Effekt VSCode extension offered in the pop-up in the bottom right.

2. Customize the project:

   • Open flake.nix and update the project name and other relevant values (follow the comments).
   • Push your flake.nix file after the changes and see if the CI agrees.

3. Set-up auto-update CI in order to get weekly PRs on Tuesday which update the Effekt version in CI:

   • Go to Settings -> Actions -> General:
     • and set "Workflow permissions" to "Read and write permissions"
     • and check "Allow GitHub Actions to create and approve pull requests"
   • See the CI section for more details

4. Replace this README with your own!

Useful commands

Effekt commands

Run the main file:

effekt src/main.effekt

This (like many other Effekt commands) uses the JavaScript backend by default. To use a different backend, add the --backend <backend> flag.

Run the tests:

effekt src/test.effekt

Open the REPL:

effekt

Build the project:

effekt --build src/main.effekt

This builds the project into the out/ directory, creating a runnable file out/main.

To see all available options and backends, run:

effekt --help

Nix-related commands

While Nix installation is optional, it provides several benefits:

Update dependencies (also runs automatically in CI):

nix flake update

Open a shell with all necessary dependencies:

nix develop

Run the main entry point:

nix run

Build the project (output in result/bin/):

nix build

Example projects using this template

• see the effekt-community GitHub organization
• This very project!

Repository structure

• .github/workflows/*.yml: Contains the CI definitions
• src/: Contains the source code
  • main.effekt: Main entry point
  • test.effekt: Entry point for tests
  • lib.effekt: Library code imported by main and test
• flake.nix: Package configuration in a Nix flake
• flake.lock: Auto-generated lockfile for dependencies
• LICENSE: Project license
• README: This README file

CI

Two GitHub Actions are set up:

1. flake-check:

   • Checks the flake.nix file, builds and tests the project
   • Runs on demand, on main, and on PRs
   • To run custom commands, add a step using:
     • nix run -- <ARGS> to run the main entry point with the given arguments
     • nix develop -c '<bash command to run>' to run commands in the correct environment

2. update-flake-lock:

   • Updates package versions in flake.nix
   • Runs on demand and weekly (Tuesdays at 00:00 UTC)