How I built My universal code transformation language — write transforms once, run them on TypeScript, Python, Go, Rust, and more

got tired of writing one-off codemods and migration scripts that only worked on one codebase and were impossible to read six months later. So I built Delta — a language specifically designed to describe how code should change. Six constructs: patch — replace a specific function in a specific file (AST-accurate) fix — reusable pattern→replacement with $VAR captures, glob scoping intent — inject code at every function entry/exit across matching files migrate — rename symbols, move files, remove deprecated API