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Anders Hejlsberg

Anders Hejlsberg

@anders-hejlsberg · 26 positions · On ppll ↗

Danish software engineer and Microsoft technical fellow, creator of Turbo Pascal and Delphi and lead architect of C# and TypeScript.

Anders Hejlsberg did not write this page.

We collected these quotes from things they published elsewhere, and every quote links to where it was said. They have no account here and have not endorsed this site. Quotes are word for word; the short line under each one is our own restatement, not their wording. Their own site. Is this you? Claim it or ask us to remove it. Or tell us what is wrong here.

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  1. Our reading

    A programming language is not a compiler but an experience: editing, running, debugging and the runtime library all have to fit together as one cycle.

    compilers

    Their wordsThat was always the idea, and that that goes back even to the predecessor of Turbo Pascal, this idea that it's not just a compiler. It's an experience, right? I mean, you don't just compile your programs. You also edit them. You also run them. You also debug them. You also have a runtime library. It all has to like fit together.
    spoken · machine transcript hear it at 0:09:10 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 1st of 26 in this recording

  3. Our reading

    Turbo Pascal won because it was ten times better at a tenth of the price — faster, smaller, more interactive and cheaper at once.

    Their wordsIt was just better than all the competition. It was faster. It was smaller. Um it was more interactive and it was also cheaper. So, it was like 10 times better at a tenth of the price of the of the competition, right?
    spoken · machine transcript hear it at 0:11:17 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 2nd of 26 in this recording

  5. Our reading

    It is a bad strategy to bet your development platform on technology licensed from a competitor.

    Their wordsAnd so, we kind of realized at that point, too, that maybe it's not a great strategy to to place your your development platform bet on on technology that's licensed from a competitor.
    spoken · machine transcript hear it at 0:17:39 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 3rd of 26 in this recording

  7. Our reading

    C# exists because developers wanted both things at once: the power and productivity of C++ with the ease of use of Visual Basic.

    Their wordsWell, like I said, I mean the the overarching thing was this: power and productivity of C++ with the ease of use of Visual Basic in a sense, right?
    spoken · machine transcript hear it at 0:19:49 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 4th of 26 in this recording

  9. Our reading

    A language should be designed by a small group of people rather than by one person.

    design

    Their wordsI think early on we decided that we want to have a team of people design this language, not just one.
    spoken · machine transcript hear it at 0:22:03 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 5th of 26 in this recording

  11. Our reading

    Language design is ninety per cent the same work every time and ten per cent new, which is why the experience carries from one language to the next.

    designcompilers

    Their wordsAnd quite honestly, language design is 90% the same and 10% new for for pretty much every language. Every language you build still has to have a compiler. Compiler is still built in a pretty much the same way.
    spoken · machine transcript hear it at 0:22:41 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 6th of 26 in this recording

  13. Our reading

    The job of a design group is to try to shoot down every new idea; the ones that survive the attempt are probably the good ones.

    design

    Their wordsAnd everyone was cognizant of okay, if someone comes up with a new idea, now it's our job to try to shoot it down. What What's wrong with this idea? Do Do you know what I mean? And if it could go if it could stand the the test of of that, then it was probably a decent idea.
    spoken · machine transcript hear it at 0:23:43 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 7th of 26 in this recording

  15. Our reading

    Writing state machines by hand is a nightmare and exactly the kind of transformation a compiler should do for you — which is all await really is.

    compilers

    Their wordsYou can have the compiler write the state machine. If you introduce syntax that allows you to indicate where you want to yield. And that's what await is.
    spoken · machine transcript hear it at 0:30:51 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 8th of 26 in this recording

  17. Our reading

    Function colouring is the real cost of async/await, and green threads like Go's avoid it — but for an existing runtime such as JavaScript or C#, async/await was still the right solution.

    JavaScript

    Their wordsSo that's unfortunate, and that's why some environments like Go, for example, has has Go routines and green threads, which are really language emulated lightweight threads that kind of do what I'm talking about, but but at a much lower cost. But you avoid the function coloring. So there is a bunch of different things, but but you know, but for an environment that already exists like JavaScript or like C# and and the Windows event loop and and whatever, this this was the right solution.
    spoken · machine transcript hear it at 0:33:05 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 9th of 26 in this recording

  19. Our reading

    The language that actually delivered write-once-run-anywhere was not Java but JavaScript, because every new device turned out to ship a browser.

    JavaScript

    Their wordsbut lo and behold, they all run browsers with JavaScript in it. Lo and behold, the real cross-platform language isn't Java. It's JavaScript.
    spoken · machine transcript hear it at 0:34:51 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 10th of 26 in this recording

  21. Our reading

    You cannot be best of breed in an ecosystem by telling its developers to write in a different programming language.

    JavaScript

    Their wordsI mean, surely you're not going to be best of breed in the JavaScript ecosystem by telling people to write in a different programming language.
    spoken · machine transcript hear it at 0:36:15 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 11th of 26 in this recording

  23. Our reading

    You cannot build good tooling without a type system — decent tooling perhaps, but nothing that scales to a large team.

    developer tools

    Their wordswe knew from experience that you cannot build good tooling without a type system. You can build decent tooling, but it's never going to scale. It's never going to scale to large teams cuz you can't describe your intents in in the code.
    spoken · machine transcript hear it at 0:36:58 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 12th of 26 in this recording

  25. Our reading

    A proprietary language licensed from Microsoft had zero chance in the JavaScript ecosystem: TypeScript had to be open source or nobody would come.

    TypeScriptopen sourceJavaScriptMicrosoft

    Their wordsAnd we we full well knew that there was absolutely zero chance that we would appeal to the JavaScript ecosystem with a proprietary programming language licensed from Microsoft. No. No one was going to come. It had to be open source. There was just no two ways about it, right?
    spoken · machine transcript hear it at 0:38:34 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 13th of 26 in this recording

  27. Our reading

    Publishing the source is not the same as developing in the open, and only the second changes how the work actually goes.

    open source

    Their wordsYou know, there's open source and there's open development. And and and we were technically open source in the beginning, but it was not open development. We would sort of lob the source code out in this repository and scrape the issues off of that and put it into our internal issue tracker.
    spoken · machine transcript hear it at 0:39:42 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 14th of 26 in this recording

  29. Our reading

    People adopted TypeScript for the tooling, not the types: an erasable type system is worth having because of the productivity the tooling built on it delivers.

    TypeScriptdeveloper tools

    Their wordsAnd the reason they came, I think, is absolutely because of the the better tooling. And I think we were totally right there that like adding a an erasable type system and then using that to enable great tooling is really where the pro where the programmer productivity boost is realized.
    spoken · machine transcript hear it at 0:41:24 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 15th of 26 in this recording

  31. Our reading

    A compiler that also serves an IDE has to be lazy and deferred throughout — a different way of building compilers from the one the textbooks teach.

    developer toolscompilers

    Their wordsAnd so everything is lazy and deferred and functional and reusable inside the compiler. And it's a very different way of writing compilers than than what the textbooks will traditionally teach you.
    spoken · machine transcript hear it at 0:47:36 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 16th of 26 in this recording

  33. Our reading

    What makes TypeScript unlike almost every other language is gradual typing: you can have types, but you do not have to.

    TypeScript

    Their wordsThe thing that makes it interesting, I think, and and unlike pretty much any other programming language is the gradual typing. This This notion that you can have types, but you don't have to have types.
    spoken · machine transcript hear it at 0:50:19 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 17th of 26 in this recording

  35. Our reading

    Because its types are erased before the program runs, TypeScript can afford not to be sound: checking 99% beats the 0% JavaScript checked, and buys features a sound language cannot offer.

    TypeScriptJavaScript

    Their wordsSo, if we're checking 99% instead of 100%, well, heck, that's better than the 0% that JavaScript checked, right? And it gives you like language features that no other languages can provide because they can't get to 100%.
    spoken · machine transcript hear it at 0:51:52 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 18th of 26 in this recording

  37. Our reading

    The language best suited to AI is simply the one the models have seen most of in training, which is why they do so well on JavaScript, TypeScript and Python.

    TypeScriptLLMsJavaScriptPython

    Their wordsthat the language that's most suited for AI is the language that AI has seen the most of in its training set, right? And that's why you could argue AI does really well on JavaScript and TypeScript and Python because it's seen an awful lot of it
    spoken · machine transcript hear it at 0:56:24 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 19th of 26 in this recording

  39. Our reading

    Forcing an AI to annotate every type would make its programs worse, not better: annotate where there is no context, and let inference do the rest.

    code generation

    Their wordsbecause if you were to force AI to write a type annotation on everything, then it would probably get it wrong more often because now it has to keep track of all these types and and it and it has to just repeat itself over and over and over, right? And so, types are important where there's no context.
    spoken · machine transcript hear it at 0:57:21 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 20th of 26 in this recording

  41. Our reading

    The internet is already past peak truth, and picking out training data worth learning from will only get harder.

    LLMs

    Their wordsI mean, you could argue that we we're already past peak truth on the on the on the internet, right? And now there's there's just more and more garbage every every day. It gets harder and harder to suss out the stuff that you do want to include in the training set in order to actually make something more intelligent.
    spoken · machine transcript hear it at 0:58:33 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 21st of 26 in this recording

  43. Our reading

    Locality is what makes a language good for AI: if a single file states what it imports and what it offers, a model never has to hold the whole program at once.

    coding agents

    Their wordsbut but if you have good locality where you you clearly stating what you're importing and whatever and and you can analyze just a single source file and from that extract its protocol to the outside world without having to to know anything deeper. Do you do you know what I mean? I think those are important aspects just simply to reduce the size of the of the of the context window and also make it easier to summarize each module in a program, right?
    spoken · machine transcript hear it at 0:59:32 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 22nd of 26 in this recording

  45. Our reading

    An agent grepping for a name is not semantic search, and the language services an IDE already has are what AI will increasingly need.

    coding agentsdeveloper tools

    Their wordsAI today it's just starting to to become aware of you know the existence of of of language services and agents today like to use grep and awk and whatever you know to to find all the places where you reference a certain thing but it's not semantic search, right?
    spoken · machine transcript hear it at 1:00:58 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 23rd of 26 in this recording

  47. Our reading

    Programmers are turning into project managers of an army of junior agents, and the craft is moving from writing code to reviewing it and holding the architecture.

    coding agentsAI and jobsAI and human skillmanagement

    Their wordsIn a sense, we're all turning into project managers, right? And and we can have an army of junior programmers called agents that will just spit out reams of code, but someone's got to have the big picture and review all of that. And so, increasingly our craft is going from one of writing the code to one of of reviewing the code and and building the architecture of the code and overseeing the work, if if you will.
    spoken · machine transcript hear it at 1:03:11 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 24th of 26 in this recording

  49. Our reading

    Responsibility for a program lies with the programmer and never with the AI — there is nobody else to hold to account.

    coding agents

    Their wordsAnd ultimately also, you know, the responsibility for a program does not lie with the AI. It lies with the programmer.
    spoken · machine transcript hear it at 1:05:00 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 25th of 26 in this recording

  51. Our reading

    A programming language is a ten-year play: version one has issues, version two fixes them, version three is finally good — and only then does adoption start.

    TypeScript

    Their wordsBut but the thing is like doing programming languages, you come to realize it's a long play. I mean, if if you look back at the the stuff I worked on, it it it goes in 10-year cycles at least. And TypeScript didn't really, for example, or C# for that matter. I mean, it took it it takes 10 years to get to, you know, version one is great, but it has all sorts of issues, and then you got to do version two, and then it's not until version three that it really starts to be great.
    spoken · machine transcript hear it at 1:12:21 · all korrents from this recording

    ↗TypeScript, C# and Turbo Pascal with Anders Hejlsbergyoutube.com 26th of 26 in this recording