v0.6.1

This release includes mainly fixes to the scikit-learn interface interface and some additional CI and packaging fixes.

Wheels available on PyPI.

Changelog

Scikit-learn interface

• Refactored SymbolicRegressor to follow scikit-learn conventions: None defaults for mutable parameters, single-underscore private methods for proper subclassing
• Replaced __check_parameters() (which mutated self) with _resolve_params() that returns a resolved dict without side effects
• Added _validate_params() for comprehensive parameter validation
• fit() now sets n_features_in_ and feature_names_in_ attributes
• Fixed MinimumDescriptionLengthEvaluator call to pass the required likelihood argument
• Expanded docstrings with type hints and corrected example import paths

C++ bindings

• Fixed dead code in UserDefinedEvaluator.__call__ where gil_scoped_acquire was placed after a return statement (source/evaluator.cpp)
• Removed duplicate read-only property for PrimitiveSet that was shadowing the read-write version (source/problem.cpp)
• Fixed typo in dataset error message and removed redundant type cast attempts (source/dataset.cpp)
• Removed unused InitAutodiff declaration from the header (include/pyoperon/pyoperon.hpp)

CI / Build

• Split build-wheels.yml into separate build-linux.yml, build-macos.yml, and a shared test.yml (reusable workflow) for independent status badges
• Added a test gate: wheel builds only proceed after pytest passes
• Linux wheels now use a matrix strategy (parallel builds per Python version) instead of a sequential loop
• Removed generator from CMake presets — resolves ninja/make conflicts on macOS when scikit-build-core auto-detects the build tool
• Fixed pip wheel to use SKBUILD_CMAKE_ARGS environment variable for passing CMake presets (replaces non-portable -C flag)
• Added --no-deps to pip wheel to prevent building dependency wheels into dist/
• Deleted legacy setup.py, ci.yml, and build-nix.yml workflows

Packaging

• Consolidated packaging on pyproject.toml with scikit-build-core
• Updated requires-python to >=3.10
• Added [project.optional-dependencies] test = ["pytest>=7.0"]
• Updated environment.yml: scikit-build replaced with scikit-build-core

Tests

• Added tests/test_sklearn.py with unit tests (parameter resolution, validation, no mutation), sklearn interface tests (clone, get/set params, repr), and integration tests (fit/predict, cross-validation, multi-objective, warm start, etc.)

Docs

• Updated README build instructions to reflect current Nix and Conda workflows
• Fixed README badges to link to the correct workflows