GHC2024 In Swarm: Modern Haskell Language Edition

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GHC2024 Language Edition Discussion for Swarm Game

Hey guys! Let's dive into a discussion about integrating the GHC2024 language edition into our Swarm game project. This is a pretty exciting step towards modernizing our Haskell codebase, and I'm stoked to explore the possibilities it opens up.

The Case for GHC2024

Our project currently supports GHC 9.6 and later versions, which means we can already leverage the GHC2021 language edition in our Cabal file. But, why stop there? GHC 9.10 brings the GHC2024 edition to the table, and while we can manually add extensions to our common stanza, adopting the full edition offers a cleaner and more streamlined approach. We're already making extensive use of features like LambdaCase and GADTs, so the new additions in GHC2024 should seamlessly integrate into our codebase.

The primary motivation behind considering GHC2024 is to enhance code readability and maintainability. By embracing the latest language features, we can reduce boilerplate and write more expressive code. This not only makes our codebase easier to understand but also simplifies the process of onboarding new developers. Let's be real, who doesn't love cleaner code?

The official proposal (GHC2024 Proposal) thoroughly documents the reasoning behind its inclusion, and it's worth checking out to fully grasp the benefits. Essentially, GHC2024 is designed to bring together a set of widely used extensions into a cohesive language edition, promoting consistency and best practices across Haskell projects.

Proposed Solution

So, how do we go about implementing this? Here's a breakdown of the steps I'm proposing:

  1. Embrace GHC2021 in Cabal: We'll start by explicitly declaring the use of the GHC2021 language edition in our Cabal file. This is our foundation, ensuring we're aligned with a modern Haskell standard.
  2. Add GHC2024 Additions to Common Stanza: Next, we'll incorporate the specific additions from GHC2024 into our common stanza. This is where the magic happens, bringing the new features into our project.
  3. Tooling Check (Fourmolu/HLint): It's crucial to ensure our tooling, specifically Fourmolu and HLint, are aware of these default extensions. We'll need to configure them to understand the new language features and avoid any formatting or linting conflicts. This step is critical for maintaining code consistency.
  4. Pragma Cleanup: With the new extensions enabled by default, we can remove the now-redundant LANGUAGE pragmas from our individual Haskell files. This decluttering step is going to make our files cleaner and easier to read. Think of it as a spring cleaning for our code!
  5. Enjoy Modern Haskell: Finally, we get to reap the rewards of our efforts and enjoy the benefits of a more modern and expressive Haskell codebase. This is the best part, obviously! 😎

Diving Deeper into the Steps

Let's break down each step in a bit more detail:

1. Embrace GHC2021 in Cabal

This step is relatively straightforward. We need to modify our Cabal file to include the language: GHC2021 declaration. This tells the compiler that we want to use the GHC2021 language edition as the basis for our project.

-- Example Cabal file snippet

executable swarm-game
  main-is:             Main.hs
  -- ... other configurations ...
  default-language: GHC2021

2. Add GHC2024 Additions to Common Stanza

This is where we bring in the specific features of GHC2024 that we want to use. We'll add the necessary extensions to the common stanza in our Cabal file. This ensures that these extensions are enabled for all components of our project.

The extensions included in GHC2024 are:

  • ApplicativeDo
  • ConstraintKinds
  • DataKinds
  • DerivingStrategies
  • QualifiedDo
  • StandaloneKindSignatures
  • Strict
  • StrictData
  • TypeData

Here's how we can add these to the common stanza:

common common-options
  -- ... other configurations ...
  ghc-options:          -Wall -Wcompat -Widentities -Wincomplete-record-updates -Wincomplete-uni-patterns -Wmissing-export-lists -Wmissing-home-modules -Wpartial-fields -Wredundant-constraints
  default-extensions:
    ApplicativeDo,
    ConstraintKinds,
    DataKinds,
    DerivingStrategies,
    QualifiedDo,
    StandaloneKindSignatures,
    Strict,
    StrictData,
    TypeData

3. Tooling Check (Fourmolu/HLint)

This is a crucial step to ensure our code formatting and linting tools are aligned with the new language features. We need to configure Fourmolu and HLint to recognize the GHC2024 extensions. This might involve updating their configurations or using specific command-line flags.

For Fourmolu, this might involve updating the .fourmolu.yaml file to include the new extensions. For HLint, we might need to update the .hlint.yaml file or use command-line flags to specify the extensions.

4. Pragma Cleanup

Now that the GHC2024 extensions are enabled by default, we can remove the corresponding LANGUAGE pragmas from our Haskell files. This cleanup will make our files less cluttered and easier to read. We can use a simple script or a find-and-replace operation in our editor to remove these pragmas.

For example, if we have a file with {-# LANGUAGE LambdaCase #-}, we can remove this pragma since LambdaCase is now included by default.

5. Enjoy Modern Haskell

With all the previous steps completed, we can now enjoy the benefits of a more modern Haskell codebase. The GHC2024 extensions offer a range of improvements, including enhanced expressiveness, reduced boilerplate, and improved code clarity. This should make our development process smoother and more enjoyable.

Alternatives Considered

We did consider a more conservative approach, sticking with our semi-GHC2021 setup using the common stanza. However, this leads to noise in both the Cabal file and individual Haskell files. By fully embracing GHC2024, we can eliminate this noise and achieve a cleaner, more consistent codebase. While the incremental approach might seem safer initially, the long-term benefits of adopting the full language edition outweigh the perceived risks.

Additional Context and Resources

To further explore this topic, here are some useful resources:

Let's Discuss!

So, what do you guys think? I'm eager to hear your thoughts, concerns, and suggestions on this proposal. Let's discuss the best way to move forward and make our Swarm game codebase even better!

We need to consider the potential impact on our existing codebase and ensure that the transition is as smooth as possible. This might involve running thorough tests and addressing any compatibility issues that arise. The goal is to adopt GHC2024 without introducing any regressions or disrupting our development workflow. We should also think about the learning curve for developers who are not yet familiar with all the GHC2024 features. Providing clear documentation and examples will be essential to ensure everyone can effectively use the new language features.

Furthermore, we need to establish a clear plan for handling any issues that might arise after the transition. This includes setting up monitoring and logging to detect any unexpected behavior and having a rollback plan in case we need to revert to the previous configuration. Communication is also key. We should keep the entire team informed about the progress of the transition and any potential challenges.

In addition to the technical aspects, we should also consider the impact on our project's long-term maintainability. By adopting GHC2024, we are aligning ourselves with the latest Haskell standards, which should make it easier to attract and retain talented developers. However, we also need to ensure that our codebase remains compatible with future GHC versions. This means staying informed about the evolution of the Haskell language and proactively addressing any potential compatibility issues.

Finally, let's not forget the fun part! Embracing GHC2024 gives us the opportunity to explore new programming paradigms and techniques. The new language features can help us write more concise, expressive, and efficient code. This is a chance to push the boundaries of what's possible with Haskell and create a truly amazing game.