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Catalyst Rules

Static performance analysis for Crystal. 49 rules to detect allocation anti-patterns, algorithmic complexity issues, and resource leaks.

ID	Rule	Severity	Confidence	Fix
CAT-001	sort.first → min/max	warning	high	✅
CAT-002	map{}.sum → sum{}	warning	high	✅
CAT-003	select + reject → partition	info	high	❌
CAT-004	Array#include? in loop → Set	warning	high	❌
CAT-005	shift/unshift → Deque	info	high	❌
CAT-006	hash.keys.each → each_key	info	high	✅
CAT-007	reverse.each → reverse_each	hint	high	✅
CAT-008	select.first/last → find	warning	high	✅
CAT-009	group_by for counters	info	medium	❌
CAT-010	String#+ in loop → String.build	warning	high	❌
CAT-011	Multi-pass gsub	hint	medium	❌
CAT-012	JSON.parse → Serializable	info	low	❌
CAT-013	TCPSocket resource leak	error	high	❌
CAT-014	File.read → streaming	info	high	✅
CAT-015	Struct vs Class heuristic	info	medium	❌
CAT-016	Large union types	info	medium	❌
CAT-017	Time.local → Time.utc	hint	high	✅
CAT-018	String#downcase == → compare	hint	medium	✅
CAT-019	Regex.new in loop → constant	warning	high	✅
CAT-020	IO::Memory for unread output	warning	high	✅
CAT-021	values.each → each_value	info	high	❌
CAT-022	shuffle.first → sample	info	high	❌
CAT-023	includes? on String → char comparison	info	medium	❌
CAT-024	keys/values.map → each_key/each_value	info	high	❌
CAT-025	File.open resource leak	error	high	❌
CAT-026	Dir.open resource leak	error	high	❌
CAT-027	Tempfile resource leak	error	high	❌
CAT-028	HTTP::Client resource leak	error	high	❌
CAT-029	DB.open resource leak	error	high	❌
CAT-030	keys.includes? → has_key?	info	high	❌
CAT-031	values.includes? → has_value?	info	high	❌
CAT-032	split.first → split_limit	info	medium	❌
CAT-033	select.map → single-pass	warning	medium	❌
CAT-034	each_with_index.map → map_with_index	info	high	❌
CAT-035	split("") → each_char	hint	high	❌
CAT-036	chars.each → each_char	info	high	❌
CAT-037	Logging with block form	info	high	❌
CAT-038	Capacity hints for large collections	info	medium	❌
CAT-039	Regex.new in method → constant	warning	high	❌
CAT-040	String.build for simple literals	hint	low	❌
CAT-041	Parsing to constant	hint	low	❌
CAT-042	sleep(0) → Fiber.yield	hint	high	❌
CAT-043	Random.new reuse	info	medium	❌
CAT-044	** power → Math.pow	info	low	❌
CAT-046	reverse.reverse no-op	hint	high	❌
CAT-047	upcase.downcase / downcase.upcase no-op	hint	high	❌
CAT-048	puts to_s redundant	hint	high	❌
CAT-049	Thread.new → spawn	warning	high	❌
CAT-050	Fiber.new → spawn	warning	high	❌