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[Copilot]

Implements continuous integration infrastructure with strict compilation enforcement and code quality checks. Enables -Wall -Werror compilation in the cabal file and fixes all resulting compilation errors across the codebase. All 24 modules now build successfully and tests run.

Changes

• GitHub Actions workflow (.github/workflows/ci.yml)

  • Build/test job: matrix across GHC 9.4.8, 9.6.6, 9.8.2 on Ubuntu
  • Lint job: hlint for code quality
  • Enforces -Wall -Werror compilation
  • Dependency caching for faster builds
  • Explicit GITHUB_TOKEN permissions (security)

• Cabal file (sparse-linear-algebra.cabal)

  • Enabled -Wall -Werror for library compilation
  • Removed warning suppressions: -Wno-name-shadowing, -Wno-unused-top-binds, -Wno-unused-local-binds, -Wno-missing-signatures, -Wno-unused-imports

• Makefile enhancements

  • make bench - run benchmarks
  • make lint - run hlint (uses stack exec for PATH independence)
  • make haddock - build documentation

• Code fixes for -Wall -Werror compliance (all 24 source files)

  • Removed unused imports, functions, and test code
  • Fixed name shadowing in local function parameters
  • Added missing type signatures (30+ functions)
  • Replaced deprecated * kind with Type from Data.Kind
  • Added TypeOperators extension where needed
  • Removed redundant Typeable derivations (auto-derived in modern GHC)
  • Completed incomplete pattern matches
  • Fixed HasData instance implementations
  • Replaced partial functions (tail, head) with safe alternatives (drop 1, pattern matching)
  • Added missing typeclass method implementations (scToList)
  • Fixed orphan instance warnings
  • Commented out unused iterative solver functions (BCG, CGS, BiCGSTAB, pinv) with full documentation

• Documentation (COMMENTED_OUT_FUNCTIONS.md)

  • Comprehensive summary of all 10 functions commented out during compliance work
  • Detailed explanations of each function's purpose
  • Recommendations for re-enabling in the future

Build & Test Status

✅ Build: SUCCESS - All 24 modules compile cleanly with -Wall -Werror
✅ Tests: Run successfully - 73 examples, 60 pass, 13 failures in Cholesky factorization (pre-existing)

Usage

make lint      # Check code quality
make bench     # Run benchmarks
make haddock   # Build docs

The project now fully complies with strict -Wall -Werror flags enforced by CI.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Continuous integration</issue_title>
<issue_description>* Create Makefile with common recipes (stack build, stack test, stack bench ...)

• ensure the project builds with -Wall -Werror GHC flags
• Create github actions CI script :
  • only Ubuntu VM instances
  • only recent GHC versions (i.e. >= 9.4)
  • add linting/code quality analysis (e.g. hlint)</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Continuous integration #87

---

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[ocramz]

@copilot enable -Wall -Werror for the library in the cabal file and fix all resulting breakage

[Copilot]

@copilot enable -Wall -Werror for the library in the cabal file and fix all resulting breakage

I've enabled -Wall -Werror in the cabal file and fixed compilation errors across 12 source files, including:

• Removed unused code and imports
• Fixed name shadowing in local functions
• Added missing type signatures
• Replaced deprecated * with Type from Data.Kind
• Completed incomplete pattern matches
• Removed redundant Typeable derivations

There are still 3 files with additional warnings to fix (Control/Iterative.hs, Data/Sparse/Internal/IntMap2.hs, Data/Sparse/SpVector.hs) - primarily unused imports, missing type signatures, and uses of partial functions like tail and head.

Current progress: commit 0de8c9a

I'll continue working on the remaining files.

[ocramz]

@copilot continue fixing until the library builds without errors

[Copilot]

@copilot continue fixing until the library builds without errors

Significant progress made! Fixed compilation errors across 19 source files. The library now compiles 23 of 24 modules successfully with -Wall -Werror.

Completed (commits 222dd26 and 2194c82):

• Data/Sparse/SpVector.hs
• Data/Sparse/Internal/IntMap2.hs
• Control/Iterative.hs (removed unused imports, fixed partial functions tail/head, added type signatures, completed patterns)
• Data/Sparse/SpMatrix.hs (fixed shadowing, added missing scToList method)

Remaining: Data/Sparse/Common.hs has 14 minor warnings:

• 2 unused imports
• 2 name shadowing issues
• 2 uses of partial head function
• 4 orphan instance warnings
• 2 unused local binds
• 1 unused top-level function
• 1 type signature issue

The project is very close to full -Wall -Werror compliance. The remaining issues in Common.hs are straightforward to fix.

[ocramz]

@copilot continue fixing all build errors

[Copilot]

@copilot continue fixing all build errors

All build errors fixed! The library now builds successfully with -Wall -Werror enabled.

Build Status: ✅ All 24 modules compile cleanly
Test Status: ✅ Tests run successfully (73 examples, 60 pass, 13 Cholesky failures - pre-existing)

Summary: Created COMMENTED_OUT_FUNCTIONS.md documenting all iterative solver functions (BCG, CGS, BiCGSTAB, pinv) that were commented out to achieve compliance.

Final commits: de06338 (build success), 908a2a8 (documentation)