cache-recursive-calls

When to Use

• Recursive function computes same inputs multiple times
• Overlapping subproblems (DP)
• Fibonacci-like recurrence relations
• Tree/graph traversal with revisits
• Expensive pure functions called repeatedly

When NOT to Use

• Function has side effects
• Inputs aren't hashable
• Cache would grow too large
• Each input computed only once

The Pattern

Use @functools.cache (Python 3.9+) or @functools.lru_cache(None) to memoize.