# The history of C# and TypeScript with Anders Hejlsberg | GitHub Source: https://www.youtube.com/watch?v=uMqx8NNT4xY Recap page: https://rapidrecap.app/video/uMqx8NNT4xY Generated: 2026-01-27T17:43:04.338+00:00 --- ## Quick Overview Anders Hejlsberg, the programming language designer behind TypeScript, C#, Turbo Pascal, and Delphi, discusses the evolution of language development, emphasizing that TypeScript's success stems from its ability to bring type safety and structure to JavaScript, which was crucial for building large-scale applications, especially as AI tools begin to automate code generation. **Key Points:** - Anders Hejlsberg is the programming language designer responsible for influential languages like TypeScript, C#, Turbo Pascal, and Delphi. - Hejlsberg discussed the shift from Turbo Pascal to Delphi, noting that Delphi's success came from providing a much better development experience than line-based editors, especially concerning the ability to quickly run code. - TypeScript's core value is providing structure and type safety to JavaScript, which is vital for building large, complex applications that would otherwise be chaotic and difficult to maintain. - The existence of TypeScript is partly a reaction to the shortcomings of JavaScript's dynamic nature when dealing with large codebases, where type errors are caught too late. - Hejlsberg noted that Microsoft's initial development of TypeScript was partly driven by the need for better tooling for their own large C# projects, which had complex internal dependencies. - He believes that while AI can automate boilerplate code, the need for human oversight and understanding of overall architecture (the 'whole thing') remains, especially concerning large-scale, complex systems. - Hejlsberg stated that the open-source nature of TypeScript, as seen by its adoption on GitHub, has been essential to its growth and success. ![Screenshot at 00:02: An establishing shot capturing the interview setup, showing Anders Hejlsberg and Eirini Kalliamvakou seated opposite each other in a large, open studio space, surrounded by professional lighting and camera equipment, setting the scene for the discussion about language development history.](https://ss.rapidrecap.app/screens/uMqx8NNT4xY/00-00-02.jpg) **Context:** This video features a definitive interview between Eirini Kalliamvakou (Research Advisor, GitHub) and Anders Hejlsberg, a renowned programming language designer known for creating TypeScript, C#, Turbo Pascal, and Delphi. The discussion centers on Hejlsberg's career trajectory, the design philosophies behind his major projects, and how modern developments like AI impact the necessity and evolution of strongly-typed languages like TypeScript. ## Detailed Analysis Anders Hejlsberg discussed his influential career, starting with Turbo Pascal and Delphi, where he focused on creating tools that dramatically improved the developer experience, such as fast compilation and visual editors, which was revolutionary in the late 70s/early 80s. He contrasted this with the interpreter-based JavaScript environment, noting that the slow feedback loop for compiled languages was a major pain point he aimed to solve with Turbo Pascal. Hejlsberg explained that he joined Microsoft near the end of 1996 to work on Microsoft's Java development toolkit, which eventually morphed into C#. He emphasized that C# was designed to have great interoperability with the underlying Windows/JVM platforms but also to be a powerful, expressive language that avoided the pitfalls of dynamically typed languages when scaling up. This led to the development of TypeScript, which Hejlsberg describes as adding necessary structure and type safety to JavaScript, addressing the chaos that arises when large codebases (like those at Microsoft or in modern web development) rely solely on dynamic typing. He credits the open-source nature of TypeScript, especially its adoption on GitHub, for its success and growth. Hejlsberg also commented on the current state of AI in programming, noting that while AI is excellent at generating boilerplate code and fixing simple errors, the complexity of large systems still requires human oversight to manage architecture and ensure correctness, meaning senior programmers and language design skills remain relevant. He expressed optimism about the future of TypeScript, particularly as AI tools become better integrated, potentially automating the tedious parts of development while retaining the safety benefits of static typing. ### Early Language Development - Hejlsberg designed Turbo Pascal for fast compilation and short development cycles - He later created Delphi, which revolutionized the developer experience by offering an interactive approach compared to previous line-based editors. ### The Move to C# and TypeScript - Hejlsberg joined Microsoft to work on Java tools, leading to C#, which aimed for high performance and interoperability with existing platforms. TypeScript arose from the need to bring static typing benefits to large JavaScript codebases, addressing the inherent chaos of large, dynamic projects. ### The Value of Type Safety - Hejlsberg argues that TypeScript's success comes from providing necessary structure and type checking upfront, avoiding runtime errors that are costly to fix later, especially in large applications. ### The Impact of AI on Programming - While AI can automate repetitive coding tasks and generate code snippets, Hejlsberg believes the holistic understanding of architecture and the ability to manage complex systems remain human responsibilities; AI currently helps with the 'boring stuff,' not the architectural vision. ### Open Source and Community - Hejlsberg credits TypeScript's open-source nature and acceptance by the community (especially on GitHub) for its success and positive evolution, contrasting it with the more closed development of some Microsoft projects like the early C# compiler. ![Screenshot at 00:10: Anders Hejlsberg's credentials displayed, listing TypeScript, C#, Turbo Pascal, and Delphi as languages he designed.](https://ss.rapidrecap.app/screens/uMqx8NNT4xY/00-00-10.jpg) ![Screenshot at 00:26: The interview setting shows Hejlsberg and Kalliamvakou seated across from each other, indicating a formal discussion/interview format.](https://ss.rapidrecap.app/screens/uMqx8NNT4xY/00-00-26.jpg) ![Screenshot at 01:02: Hejlsberg discussing the constraints of 8-bit memory in early computing when explaining early programming challenges.](https://ss.rapidrecap.app/screens/uMqx8NNT4xY/00-01-02.jpg) ![Screenshot at 02:48: Eirini Kalliamvakou describes the frustration developers experienced with older tools, gesturing emphatically.](https://ss.rapidrecap.app/screens/uMqx8NNT4xY/00-02-48.jpg) ![Screenshot at 04:46: Hejlsberg describes the shift in programming culture from a 'one-man show' to collaborative team efforts.](https://ss.rapidrecap.app/screens/uMqx8NNT4xY/00-04-46.jpg)