GHC Version Inconsistencies

Oct 13, 2025 by talynt.org 133 views

Introduction

As a participant in the Plutus Pioneer Program, you're likely familiar with the Plutus-tx-template, a valuable resource for building and testing Plutus smart contracts. However, you may have encountered an issue where the GHC version differs between your local machine and the CI machine. In this article, we'll explore the possible reasons behind this discrepancy and provide guidance on how to resolve it.

Understanding the Plutus-tx-template

The Plutus-tx-template is a Haskell template for building and testing Plutus smart contracts. It provides a basic structure for your contract, including the necessary imports and functions. The template is designed to work with the GHC compiler, which is used to compile Haskell code.

GHC Version Inconsistencies

When you run the nix develop command on your local machine, you get GHC 9.6.6, but when you run the same command on a GitHub CI workflow, you get GHC 9.12.1. This inconsistency can cause issues with your code, as different GHC versions may have different behavior or support different features.

Possible Reasons for GHC Version Inconsistencies

There are several possible reasons why you may be experiencing GHC version inconsistencies:

Nix Configuration: The nix develop command uses a Nix configuration to manage dependencies and build your project. If the Nix configuration on your local machine is different from the one used in the CI workflow, it may lead to different GHC versions being used.
GHC Version Pinning: If you're using a specific GHC version in your project, it may be pinned to a specific version in the Nix configuration. If the CI workflow is using a different Nix configuration, it may not be pinned to the same GHC version.
Dependency Versions: The versions of dependencies used in your project may also affect the GHC version used. If the CI workflow is using a different version of a dependency, it may require a different GHC version.

Resolving GHC Version Inconsistencies

To resolve GHC version inconsistencies, you can try the following:

Check Nix Configuration: Verify that the Nix configuration on your local machine is the same as the one used in the CI workflow. You can do this by checking the nix file in your project root.
Pin GHC Version: Pin the GHC version in your Nix configuration to ensure that the same version is used on both your local machine and the CI workflow.
Update Dependency Versions: Update the versions of dependencies used in your project to ensure that they are compatible with the GHC version used in the CI workflow.
Use a Specific GHC Version: If you need to use a specific GHC version, you can specify it in your Nix configuration or in the nix develop command.

Example Use Case

Here's an example of how you can pin the GHC version in your Nix configuration:

{ pkgs ? import <nixpkgs> {} }:
pkgs.mkShell {
buildInputs = [
pkgs.ghc
];
GHC = pkgs.ghc_9_6_6;
}

In this example, we're pinning the GHC version to 9.6.6 using the GHC attribute.

Conclusion

GHC version inconsistencies can cause issues with your Plutus smart contract code. By understanding the possible reasons behind this discrepancy and following the steps outlined in this article, you can resolve GHC version inconsistencies and ensure that your code works as expected on both your local machine and the CI workflow.

Troubleshooting Tips

Check Nix Configuration: Verify that the Nix configuration on your local machine is the same as the one used in the CI workflow.
Pin GHC Version: Pin the GHC version in your Nix configuration to ensure that the same version is used on both your local machine and the CI workflow.
Update Dependency Versions: Update the versions of dependencies used in your project to ensure that they are compatible with the GHC version used in the CI workflow.
Use a Specific GHC Version: If you need to use a specific GHC version, you can specify it in your Nix configuration or in the nix develop command.

Additional Resources

Plutus Pioneer Program: The official Plutus Pioneer Program website provides resources and guidance for building and testing Plutus smart contracts.
Nix Configuration: The Nix configuration file is used to manage dependencies and build your project. You can find more information about Nix configuration in the Nix documentation.
GHC Version Pinning: You can find more information about GHC version pinning in the GHC documentation.
Q&A: Resolving GHC Version Inconsistencies with Plutus-tx-template ====================================================================

Q: What is the Plutus-tx-template and why is it relevant to GHC version inconsistencies?

A: The Plutus-tx-template is a Haskell template for building and testing Plutus smart contracts. It provides a basic structure for your contract, including the necessary imports and functions. The template is designed to work with the GHC compiler, which is used to compile Haskell code. GHC version inconsistencies can cause issues with your code, as different GHC versions may have different behavior or support different features.

Q: Why do I get different GHC versions on my local machine and the CI machine?

A: There are several possible reasons why you may be experiencing GHC version inconsistencies:

Nix Configuration: The nix develop command uses a Nix configuration to manage dependencies and build your project. If the Nix configuration on your local machine is different from the one used in the CI workflow, it may lead to different GHC versions being used.
GHC Version Pinning: If you're using a specific GHC version in your project, it may be pinned to a specific version in the Nix configuration. If the CI workflow is using a different Nix configuration, it may not be pinned to the same GHC version.
Dependency Versions: The versions of dependencies used in your project may also affect the GHC version used. If the CI workflow is using a different version of a dependency, it may require a different GHC version.

Q: How can I resolve GHC version inconsistencies?

A: To resolve GHC version inconsistencies, you can try the following:

Check Nix Configuration: Verify that the Nix configuration on your local machine is the same as the one used in the CI workflow. You can do this by checking the nix file in your project root.
Pin GHC Version: Pin the GHC version in your Nix configuration to ensure that the same version is used on both your local machine and the CI workflow.
Update Dependency Versions: Update the versions of dependencies used in your project to ensure that they are compatible with the GHC version used in the CI workflow.
Use a Specific GHC Version: If you need to use a specific GHC version, you can specify it in your Nix configuration or in the nix develop command.

Q: How can I pin the GHC version in my Nix configuration?

A: You can pin the GHC version in your Nix configuration by using the GHC attribute. For example:

{ pkgs ? import <nixpkgs> {} }:
pkgs.mkShell {
buildInputs = [
pkgs.ghc
];
GHC = pkgs.ghc_9_6_6;
}

In this example, we're pinning the GHC version to 9.6.6 using the GHC attribute.

Q: What are some troubleshooting tips for resolving GHC version inconsistencies?

A: Here are some troubleshooting tips for resolving GHC version inconsistencies:

Check Nix Configuration: Verify that the Nix configuration on your local machine is the same as the one used in the CI workflow.
Pin GHC Version: Pin the GHC version in your Nix configuration to ensure that the same version is used on both your local machine and the CI workflow.
Update Dependency Versions: Update the versions of dependencies used in your project to ensure that they are compatible with the GHC version used in the CI workflow.
Use a Specific GHC Version: If you need to use a specific GHC version, you can specify it in your Nix configuration or in the nix develop command.

Q: Where can I find additional resources for resolving GHC version inconsistencies?

A: You can find additional resources for resolving GHC version inconsistencies on the following websites:

Plutus Pioneer Program: The official Plutus Pioneer Program website provides resources and guidance for building and testing Plutus smart contracts.
Nix Configuration: The Nix configuration file is used to manage dependencies and build your project. You can find more information about Nix configuration in the Nix documentation.
GHC Version Pinning: You can find more information about GHC version pinning in the GHC documentation.