CAT 004

CAT-004 — Array#include? in loop → Set

Severity: warning • Confidence: high • Auto-fix: ❌

Description

Array#include? in loop → Set — Using Array#includes? inside a loop is O(n) per check. Use a Set for O(1) lookups.

Bad code

large_array.each do |x|
  if other_array.includes?(x)
    ...
  end
end

Performance Impact

Tip

This rule can significantly improve performance in hot code paths.

Benchmark

Note

See bench results at bench/cat-004/