Writing a custom parser is a fairly common need. Although there are already parser combinators in others languages, TypeScript provides a powerful and well-structured foundation for building this. Common parser combinators’ weakness are error handling and ambiguity resolving, but these are ts-parsec’s important features. Additionally, ts-parsec provides a very easy to use programming interface, that could help people to build programming-language-scale parsers in just a few hours. This technology has already been used in Microsoft/react-native-tscodegen.