Breaking Complexity: How Pure Function Extraction Transforms Legacy Codebases

Legacy code maintenance remains a critical bottleneck in software development, with tangled functions making every change risky and time-consuming. Pure function extraction—separating deterministic calculations from side effects—directly addresses this by improving testability, reducing coupling, and making code intent transparent. This approach is transformative for teams managing existing systems, converting unmaintainable monoliths into composable, reasoning-friendly architectures.