exercises

⚠️ The course authors no longer provide reviews of the solutions. However, all the learning materials are free and publicly available. You can learn Haskell on your own or with the help of others.

Exercises for the Haskell Beginners 2022 course. The course itself can be found here:

• Haskell Beginners 2022 Course

This repository contains a complete Haskell project. The project comprises four Haskell files (modules) in the src/ directory. Each module provides exercises for an individual lecture and has the corresponding name (e.g. Lecture1.hs).

Working with the course

This section contains instructions about setting up the development environment and preparing the exercises repository.

First time

1. Fork the exercises repository.

2. Enable GitHub Actions for your forked repository.

   • Visit: https://github.com/<YOUR_GITHUB_USERNAME>/exercises/actions

3. Clone your forked repository.

4. Enter the exercises directory and add the original repository as a course remote.

   git remote add course https://github.com/haskell-beginners-2022/exercises

   You can verify that everything is done correctly by running the git remote -v command. The output of this command will look similar to the below:

   course https://github.com/haskell-beginners-2022/exercises (fetch)
   course https://github.com/haskell-beginners-2022/exercises (push)
   origin [email protected]:chshersh/exercises.git (fetch)
   origin [email protected]:chshersh/exercises.git (push)

Asking for feedback

Implement your solutions in a separate branch (not main). You can run the following command to create a new branch and switch to it at the same time:

git checkout -b lecture-1-solutions

When you have finished implementing exercises for a particular lecture, create a Pull Request to your fork. The repository already contains PR template with the prefilled text and mentions all current mentors of the course.

ℹ️NOTE: Open Pull Request to your fork and not this repository. We can't merge solutions to this repo. But if you open PRs to your repository, you can eventually merge all the solutions and enjoy green all-passing CI 🍏

To open a PR to your fork, you need to change base repository to your own repository, as shown on the screenshot below:

After you change, the PR view will change accordingly:

Updating your fork

The course content (exercises, tests, configuration, etc.) might change after you forked the course. To get the latest updates, follow the below instructions:

1. Switch to your main branch locally and make sure it's in sync with the latest version of your fork on GitHub.

   git checkout main
   git pull --rebase --prune

2. Fetch all the course changes and save them locally.

   git fetch course main
   git rebase course/main

   NOTE: This stage may require you to resolve conflicts.

3. Push local changes to your own fork.

   git push origin main --force

Installing Haskell

Follow the below instructions to configure the Haskell development environment.

Haskell Toolchain

To develop in Haskell, you need to install ghcup, ghc and cabal.

1. Install ghcup and follow ghcup instructions for successful installation (remember to restart your terminal afterwards to avoid an unknown ghcup command error on the next step).

2. Install the recommended version of the Haskell compiler — GHC — and the Cabal build tool. After you install ghcup, it is easy to install the rest with a few commands from your terminal, if these tools are not yet installed.

   ghcup install ghc 9.2.5
   ghcup set ghc 9.2.5
   ghcup install cabal 3.8.1.0

   You can verify that everything is installed correctly by running the following commands:

   $ ghc --version
   The Glorious Glasgow Haskell Compilation System, version 9.2.5
   $ cabal --version
   cabal-install version 3.8.1.0
   compiled using version 3.8.1.0 of the Cabal library

3. Run cabal update to fetch the latest info about Haskell packages.

Haskell IDE

If you don't have any IDE preferences, we recommend installing Visual Studio Code with the Haskell plugin. The mentioned plugin would give you everything required to immediately start coding with Haskell.

How to build and test?

There're two ways to build this project: using either cabal or stack build tools. Using cabal is the recommended way. However, if it doesn't work, you may want to use stack.

Cabal

To compile the entire project, run the following command from your terminal:

make build

To run tests for a specific lecture only (e.g. the first one), use the following command:

make test-lecture1

You can also run tests only for a single function. For example, to run tests for the strSum function, execute the following command:

cabal run exercises-test --enable-tests -- -m "strSum"

Stack

Use the official stack installation instructions to install stack.

To build the project with stack, run the following command:

stack build --test --no-run-tests

To run tests for the first lecture, run the following commands:

stack test :doctest-lecture1
stack test :exercises-test --test-arguments='-m "Lecture 1"'

And to tests a specific function, use:

stack test :exercises-test --test-arguments='-m "strSum"'