How to use a dependency’s extra-lib-dirs in stack.yaml

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Summary

The issue at hand is about dependency management in Haskell projects using Stack, where a dependency requires an external library. The dependency’s cabal.project.local file specifies extra-lib-dirs, but this configuration seems to be ignored by Stack when building the dependency.

Root Cause

The root cause of this issue is that Stack does not automatically use the local cabal project configuration when building dependencies. The reasons for this include:

  • Stack uses its own configuration files (e.g., stack.yaml) to manage dependencies
  • The cabal.project.local file is specific to Cabal, not Stack
  • Stack does not automatically merge configurations from cabal.project.local into its own build process

Why This Happens in Real Systems

This issue occurs in real systems because:

  • Dependency management can be complex, especially when dealing with external libraries
  • Configuration files can be scattered across different projects and tools (e.g., Cabal, Stack)
  • Build tools may not always be compatible or aware of each other’s configurations

Real-World Impact

The impact of this issue includes:

  • Build failures due to missing libraries or incorrect configurations
  • Increased maintenance efforts to manage dependencies and configurations
  • User frustration when trying to build and use Haskell packages

Example or Code (if necessary and relevant)

-- Example cabal.project.local file
package precisa
  extra-lib-dirs: /path/to/lib

How Senior Engineers Fix It

Senior engineers fix this issue by:

  • Specifying extra-lib-dirs in stack.yaml to ensure Stack uses the correct library paths
  • Using Cabal’s build flags to override default configurations
  • Creating custom build scripts to manage complex dependencies and configurations

Why Juniors Miss It

Junior engineers may miss this issue because:

  • Lack of experience with dependency management and build tools
  • Insufficient understanding of how different configuration files interact
  • Overreliance on default configurations without considering custom requirements

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