catalyst v0.1.0

crystal performance linter
Performance linter for Crystal. Catches allocations, O(n²) patterns, and resource leaks before they reach production.

Catalyst

Static performance analysis for Crystal.

Detects allocation anti-patterns, algorithmic complexity issues, and resource leaks before they reach production. Like Fasterer for Crystal.

Installation

git clone https://github.com/unurgunite/catalyst
cd catalyst
crystal build src/catalyst.cr --release -o bin/catalyst

Usage

# Scan a directory recursively
catalyst src/

# Scan specific files
catalyst src/app.cr src/lib.cr

# CI mode — exit code 1 on findings
catalyst --ci src/

# JSON output
catalyst --format json src/

# Apply safe auto-fixes
catalyst --fix src/

# Enable only specific rules
catalyst --rules CAT-001,CAT-002 src/

# List all rules
catalyst --list-rules

Configuration

Create .catalyst.yml in project root:

severity: warning
format: terminal

rules:
  CAT-001:
    severity: error

ignore:
  - lib/**
  - "**/*_spec.cr"

paths:
  - src/

Rules

ID Rule Severity Fix
CAT-001 sort.first → min/max warning ✅
CAT-002 map{}.sum → sum{} warning ✅
CAT-003 select + reject → partition info ✅
CAT-004 Array#include? in loop → Set warning ❌
CAT-005 shift/unshift → Deque info ❌
CAT-006 hash.keys.each → each_key info ✅
CAT-007 reverse.each → reverse_each hint ✅
CAT-008 select.first/last → find warning ✅
CAT-009 group_by for counters info ❌
CAT-010 String#+ in loop → String.build warning ❌
CAT-011 Multi-pass gsub hint ❌
CAT-012 JSON.parse → Serializable info ❌
CAT-013 TCPSocket resource leak error ❌
CAT-014 File.read → streaming info ✅
CAT-015 Struct vs Class heuristic info ❌
CAT-016 Large union types info ❌
CAT-017 Time.local → Time.utc hint ✅
CAT-018 downcase == → compare hint ✅
CAT-019 Regex.new in loop → constant warning ✅
CAT-020 IO::Memory for unread output warning ✅

Development

crystal spec
catalyst src/
ameba src/

License

MIT

Repository

catalyst

Owner
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  • about 3 hours ago
  • July 7, 2026
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Fri, 10 Jul 2026 14:20:02 GMT

Languages
Crystal 100.0%