[tinyvm]

I recently did the exact same job as the author of this post.

Migrating 15K LoC from JS to TS.

The author of Vue.JS also migrated Vue completely to Typescript.

At first I had major apprehension because of how much Microsoft generally enforces things on developers.

It's well know that if you start using C# , your entire stack will generally be MS based...(SQL Server, Azure etc... )

But after I did the migration , I was blown away by how confident and how much flexibility I had when i was writing my code.

Even if I have been writing code with Java / C# for nearly a decade , nothing has come close to Typescript in terms of productivity,flexibility and confidence.

Having used Javascript since before Node.JS , I think the whole idea of having to "transpile" my code to something or to respect some "rules" define by a company with a reputation that wasn't really "all in open source" .

But after using Typescript on multiples projects , you just can't go back , it's incredible how well it's scale without enforcing anything on the developers.

Hopefully , one day bootcamps will include Typescript in their trainings to demonstrate how typings can solve maintainability issues...

[sonnyblarney]

"Even if I have been writing code with Java / C# for nearly a decade , nothing has come close to Typescript in terms of productivity,flexibility and confidence."

Same here.

Isn't this truly amazing?

Take a jangly language like JS, and add some typing for the compiler, which forces you to write cleaner code in addition to all the compiler advantages ... combined with some really cool features and bang a magical, pragmatic language.

Aside for some script things for which Python is still a blessing, I'd chose TS for everything else, at least to start.

It just has the right mix of flexibility and expressivity etc..

Though TS is an MS project, I suggest it really is quite different, it's 'open from the start' kind of thing, you can have a loot at TSC internals. The team seems to be fairly dynamic and responsive.

Typscript is my #1 favorite 'invention' of the last few years, I think it will be around for a while, and I hope to see many more JS API's 'properly documented' with the help of TS.

[johnfn]

> Take a jangly language like JS, and add some typing for the compiler, which forces you to write cleaner code in addition to all the compiler advantages ... combined with some really cool features and bang a magical, pragmatic language.

Agreed. And when you compare how TS was designed to how other languages were designed, it makes a lot of sense why TS ended up being such a great language.

Unlike virtually every other language in existence, TS was not designed from the ground up. It was designed with a very specific goal in mind: to adhere to the standards that JS developers had already converged on. So when a JS developer said if (foo), TS was built to realize that was an implicit type check against null. When a JS developer said if (obj.type === “bar”), TS read that as a way to ensure obj was in fact a bar.

It’s unlikely that a language developer working from scratch would have come up with these odd idioms, let alone prioritized their inclusion into a new language. But in the case of TS, all these idioms came from millions of lines of working code.

I think that’s why TS feels so enjoyable and easy to work with nowadays, whereas even the best of other languages feel a little clunky at times. It was developed prioritizing making real actual code idioms people wanted to do work.

[tomnipotent]

> when you compare how TS was designed to how other languages were designed

Is it safe to say that Microsoft has probably created/designed more programming languages than any other company? I can think of a dozen off the top of my head...

[ygra]

Anders Hejlsberg, the lead architect behind TypeScript has created C# and J++ at Microsoft, and Delphi and Turbo Pascal before. It's safe to say he has some experience in designing languages.

[alasdair_]

J++ is one of the primary reasons I am so wary about using a Microsoft-invented language. "Embrace and extend" a well-used language with extra features (then make them only work well on Windows later) has always been a classic Microsoft strategy. If they could get away with it with Typescript, I'm sure they would try again.

[abhayb]

Thank you! This is the argument that made me give TypeScript a try. I work in Kotlin day to day which tries to fix its base language (and batteries included with it) while not fixing it too much. TS sounded like a language in that vein.

[untog]

The exception I'd add is that JavaScript's standard library is still very weak. I find myself leaning on Lodash for functionality that would be built into any other language.

Part of me would love for TS to build one out and add shims as part of the transpilation process, but it would go miles out of the scope of what TS is trying to do. And I love that (compared to Babel) TS has no plugins and relatively few options.

[Stoids]

To add onto this, using lodash + TS is not the most pleasant experience. A lot of that has to due with current limitations of the type system (mostly variadic types [0]), but I find myself having to provide lots of generics rather than relying on inference. The overloads are not great.

I say this all with recognition that lodash greatly predates TS, and the maintainers have done an absolutely wonderful job in keeping up with the overall ecosystem (ESM, typings files, etc). I can't even begin to comprehend the amount of work that has gone in to keeping lodash so modern.

That being said, I wish the interaction was slightly better, since a lot of people just immediately bring in Lodash to any JS project.

[0] https://github.com/Microsoft/TypeScript/issues/5453

[arcticfox]

I have the same experience; I wonder if anyone is working on a TS-friendly utility library, or if our best hope is the work on TS itself on [0]?

[chrisweekly]

I wonder if ramda is any better in that regard?

[kristiandupont]

I love Ramda and use it everywhere but sadly, it's somewhat lacking when it comes to type definitions. Everything in Ramda is curried and the types just don't reflect that very well so you get quite a few incorrect compiler errors.

[TJSomething]

Shouldn't tuples in rest parameters from TypeScript 3.0 [0] fix that?

[0] https://www.typescriptlang.org/docs/handbook/release-notes/t...

[Nimelrian]

Not entirely.

For example, a function which takes a property path (in the form of an array of strings) and an object as parameters and returns the value at that path inside the object still needs overloads for every single tuple length.

  type Key = string | number | symbol;
  
  function get<T, K extends keyof T>(path: [K], obj: T): T[K];
  function get<T, K1 extends keyof T, K2 extends keyof T[K1]>(path: [K1, K2], obj: T): T[K1][K2];
  function get<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2]>(path: [K1, K2, K3], obj: T): T[K1][K2][K3];
  function get<T, K1 extends keyof T, K2 extends keyof T[K1], K3 extends keyof T[K1][K2], K4 extends keyof T[K1][K2][K3]>(path: [K1, K2, K3, K4], obj: T): T[K1][K2][K3][K4];
  function get(path: Key[], obj: any) {
      if (path.length === 0) {
          return obj;
      }
      const key = path[0] as Key;
      const rest = path.slice(1) as [Key];
      return get(rest, obj[key]);
  }
  
  
  interface Foo {
      foo: {
          bar: {
              baz: {
                  val: number;
              }
          }
      }
  }
  
  declare const foo: Foo;
  const num = get(["foo", "bar", "baz", "val"], foo);

In this case, num is implicitly typed as number, but if the path would be longer, you'd need to add more overloads.

[arcturus17]

I keep hearing that but I dunno. I’m building a fairly large side project in Express + React and I keep finding ways of doing things in ES6 - lodash is still not to be found in package.json. I think I might cave in eventually but as it stands my code feels clean and succinct and it’s all done in modern functional style.

[untog]

One example is doing deep comparison on objects. ES6 still has no equivalent for that, and it's something you can do in one line in other languages.

[patates]

Which languages? I'd think it's rare because I know no such standard function from the top of my head.

[untog]

Swift immediately comes to mind - structs are value types. Also, Kotlin has data classes.

[julien_c]

`util.deepStrictEqual` in Node at least

[sonnyblarney]

This is a very good point.

I wish lodashy functions, and a few other things (Time?), were just integrated into JS, in a thoughtful way ... as part of the standard lib. So they could all be done in native code in the engine.

[zachrose]

I’m sympathetic to this point of view, but I find lodash to be too huge of an API. Most of the collection methods can be done as a small _.reduce, and I find the many method names and subtle distinctions to add more trivia than they remove.

[untog]

The good news is that you can use lodash as an ES6 module, with any tree-shake capable bundler stripping out all the crap. Absolutely agree it's not optimal though.

[arusahni]

This is a pain point that the community wishes to address: https://github.com/tc39/proposal-javascript-standard-library

[austincheney]

I don’t see this going very far for historical reasons. This idea has been suggested for over a decade, but back then the focus of inspiration was jQuery. The false argument was that everybody was requesting it into pages anyways so it should be part of the language. Not only was this idea proposed on top of a faulty assumption but there were also performance penalties and hidden conformance defects.

These suggestions fall apart over time because they aren’t environment agnostic and lack objectivity. The subjectivity in question, “I want feature X”, usually doesn’t take alternate positions into consideration.

[Nimelrian]

The proposal explicitly states that everything in the standard library would not be tied to specific target environments:

Such a library would only cover features which would be useful in JavaScript in general, not things which are tied to the web platform. (A good heuristic: if something would make sense on a web browser but not in node or on embedded devices or robots, it probably isn't in scope.)

[_ZeD_]

Truth be said, jQuery can be seen obsolete because most of the functionality has been moved inside the DOM or the ajax "standard library" ...

[kristiandupont]

I guess I disagree as I much prefer Ramdas style over Lodash.. Is your concern about performance? Because I don't think it would be a massive improvement over JS code.

[vinniejames]

Curious what you're still often using lodash for?

[untog]

One thing that comes to mind is comparison - array equality, deep object comparison, that sort of thing.

[weberc2]

> Aside for some script things for which Python is still a blessing, I'd chose TS for everything else, at least to start.

I really wish Python had a decent type system; hopefully the Mypy project takes a leaf from TypeScript's book.

Also, I've found that Go does for Python much of what TypeScript does for JavaScript. Of course, Go's APIs are different than Python's and its type system is less expressive than TypeScript so it's not a perfect analog, but Go also brings speed, parallelism, sane concurrency (Python's async is a hot mess by comparison), sane deployment, and great editor integrations, which are things I sorely miss when writing Python.

[klibertp]

Mypy is already quite powerful and understands a lot of the language. With latest versions of the language, what is handled by "transpiling" to JS, can be done "natively", ie. there is no need for an intermediate step to strip out the additional syntax for declaring types as it's now built in.

Mypy and TC and Flow and many other similar projects seem to stem from the academic work on gradual typing from nearly 20 years ago. What we're seeing now is "practical application" of that research, and while different projects have different budgets, it won't be surprising if they all converge in terms of features at some point. I'm not an expert, by any means, but we've already seen this happening many times with languages and software platforms. At least this time the point of convergence is based on comp-sci research and not on the marketing one.

[weberc2]

My grievance is mostly that Mypy is much less polished than TS and Flow (you can argue that it's a lack of investment and that's probably true, but it doesn't do me any good as a Python developer). Notably, Mypy's syntax is very much shoehorned in. How do I define a TypeVar for a particular method in a class? If I define a TypeVar (<T>) in the class scope, does every reference to T take on the same type? I can't honestly tell by looking if it's safe to use <T> for each generic method in a class or if the type system will try to unify them to the same type. Also, does Mypy support recursive types yet? Can I meaningfully define a JSON type without hacks (e.g., `Dict[str, Any]`)? Also, can I stub out generated types yet? IIRC, the official position for SQLAlchemy was something like "eh, it's out of scope for the project". Pretty sure there was a lot of problems with defining different kinds of callables (maybe those with args and kwargs?) not to mention a bunch of ergonomic problems because they don't want to extend the parser much (it appears they take the view that it's better to have terrible syntax that is "valid Python" without much modification to the Python parser--to be clear, this isn't referring to angle brackets vs square brackets, but things like using variable declaration syntax in an outer scope to declare a type variable for a generic context).

[pseudalopex]

Python's type annotation syntax is mostly similar to TypeScript.

Each method is independent unless the class is a Generic[T].

You can define a recursive type by quoting the nested reference.

You can define a JSON type with recursive types.

You can create stubs. Some are in typeshed.[1]

Mypy recently added protocols to simplify defining callable types.

Python has always been slow to add new syntax. I think that's a good thing overall.

[1] https://github.com/python/typeshed/

[weberc2]

> You can define a recursive type by quoting the nested reference.

No, that’s not sufficient, or at least it wasn’t. The problem wasn’t symbol resolution, but Mypy actually gave you a recursion error. At one time they were intending to fix it by implementing protocols which hadn’t landed last I checked.

> You can create stubs. Some are in typeshed.

You can, but not for magical libraries like SQLAlchemy.

> Python has always been slow to add new syntax. I think that's a good thing overall.

Probably, but it’s hindering their typing story. Typescript solves the problem by building a syntax that compiled to JS, but Python has some syntax support but lots of things are shoehorned in.

[goliatone]

I think the biggest win of Go over Python is around the single binary distribution, which I guess you included with deployments. But it truly deserves a mention on its own and it’s a major point over other (most?) languages. It really makes up for a lot of the shortcomings of Go as a language IMO. But I enjoy Go best for building system tools, the single binary doesn’t shine as much once you involve containers at which point the friction between say a Python/Node container and a Go container is pretty much the same

[weberc2]

That’s definitely up there. As for containers, I think Go’s static compilation story actually has some important ramifications for containers, namely I don’t need a set of base images for doing development since I can just toss a binary into the container and run it there (running in the container is useful because our local dev setup uses Docker Compose to orchestrate the microservices). If we could do this with Python it would simplify our CI and our development process by a good bit. And of course Go images are about a factor of magnitude smaller than Python images to boot!

[agentultra]

Turns out creating a static binary distribution can be done in Python without containers [0].

[0] http://www.pyinstaller.org/

[rpeden]

The tiny size of an Alpine + Go container is still nice compared to a typical Node or Python container, though.

[weberc2]

Try the Go/scratch combo (2.5MB): https://weberc2.bitbucket.io/posts/golang-docker-scratch-app...

[sime2009]

> Take a jangly language like JS, and add some typing for the compiler

It so turns out that there is a great sweet spot in between the straight jacket typing of classic Java/C# and the loose "do way ever you like" approach in Python/JS.

I don't want use another language that doesn't have optional typing and structural typing. It combines the best of both ends of the spectrum.

[Brometheus]

My thinking exactly.

[cellis]

Wow, almost...almost reminds me of a little known language called ActionScript 3. ;)

[_ea1k]

As someone who hated ActionScript 3, I vehemently disagree. AS3 felt like some Java guys trying to force a Java mindset on a language that didn't really suit it.

And I say that as a Java guy myself. TS is much more dynamic and less abrasive, IMO.

[goliatone]

Funny, I feel the same way about TS :) To be fair tho, you’re right. Flex was a very Java centric endeavor, from its compiler to the first big frameworks (Caignorm?) all the way to its target audience, which were enterprise companies that wanted to do their “thing” on the web. There was a massive developer migration from the Java/enterprise world to the AS3 ecosystem that had a visible impact. Also to be fair, if you look at Angular now with TS it feels even more Java’ish than ever. TS is great, is specially good for people coming from different languages in that it gives them a more familiar environment but the downside is that they have to make a lower effort to break away from old patterns and truly understand the new platform they’re working on.

[nojvek]

AS3 was a huge improvement over AS2. However Typescript type system is incredibly dynamic and malleable yet quite strict.

Typescript gets its huge strength from being able to bring a slider of type safety from pure js - Wild West crazy to strong null checked safety.

Having that pragmatic option of a slider is great for productivity.

[nicoburns]

> if you look at Angular now with TS it feels even more Java’ish than ever.

This is true, but I think it's an Angular thing rather than a TS thing.

[_ea1k]

I think it is hurting Angular in the marketplace, too.

[johnfn]

Whenever I feel in the mood to troll people, I tell them that TS is just a worse AS3. AS3 has types, classes... it even had XML literals! Eat that, JSX.

[int_19h]

To be more precise, TS is a worse ES4. AS was a partially conforming implementation of ES4 drafts that most are aware of. But Microsoft had its own thing along these lines - JScript.NET (in fact, it still ships as part of the .NET Framework, even though it's deprecated).

[nerdponx]

I've heard it said that Javascript and C are both good languages to compile to -- the language itself is very "fast" in basic operations (V8 is hyper-optimized, C is relatively close to the metal), but an ugly language with lots of gotchas and warts that make it hard for a human to use effectively, but which don't pose a problem for a well-designed compiler.

[kccqzy]

No lol. Javascript is not a good language to compile to. People compile to JavaScript only because it's the only language to run in browsers.

Most compilers, after type checking and semantic analyses, basically generate a control flow graph with basic blocks. Javascript doesn't have goto so it doesn't allow you to express those low-level things natively, which is why emscripten has to include a relooper component to turn them back into loops and conditionals.

If you want a good language to compile to, look at LLVM. It's a language designed to be compiled to, and it's mind-blowingly easy to compile to than either C or JavaScript.

[brett40324]

It's maybe worth noting here that compiling to C and transpiling to JS are two entirely different paradigms of linking and building a software release.

[mcepl]

> Aside for some script things for which Python is still a blessing, …

Have you tried using type hints (https://www.python.org/dev/peps/pep-0484/) with mypy?

[tomnipotent]

> Though TS is an MS project, I suggest it really is quite different

I'd be willing to say it's actually the "heart" of the new MS. Eliminating the incentive to selling OS licenses is doing marvels for them.

[sephoric]

I'm starting to think Microsoft's strategy with things like VS Code, Monaco editor, and Typescript is "blow the developer away with how amazingly productive they are so that they will want to use more of our products". Because it's just so high quality yet also gratis/libre (MIT license), that I can't see what else they could be trying to do.

[julienb_sea]

Honestly I also think its a recruiting tool for Microsoft. Developers watch the meaningful and useful open source contributions made by Microsoft, and some of the highbrow disinterest in Microsoft due to choices made in the past will fade.

[skohan]

Never forget "Embrace, extend, extinguish". Microsoft has a history of adopting open standards, adding value to them to gain market share, then leveraging that to destroy their competition.

Microsoft might seem to be an "open source champion" now, but remember that it is a publicly traded corporation with a fiduciary responsibility to maximize profits for its shareholders and a history of anti-competitive, anti-consumer practices.

Right now they are being warm and fuzzy to regain the developer mind-share they have lost over the past couple decades to open-source software. If they get a large percentage of developers using their tools and services (looking at you GitHub) I would not trust that they will continue to be so warm and fuzzy.

[sime2009]

I know how "Embrace, extend, extinguish" works when the product people are "locked" into is closed source and propriety. But explain to me how this works when the product is open source and can be forked by anyone?

[skohan]

They may not be able to do "Embrace, extend, extinguish" in the exact same way with their open-source efforts, but that doesn't mean they would not be able to apply leverage given sufficient market share.

Imagine if VSCode becomes the defacto code editor. Then they add seamless integration with GitHub, including value-added features which are not available from other providers like gitlab. Developers accept it because everyone uses GitHub anyway. Then they add features to GitHub to integrate seamlessly with Azure, and bug tickets related to GitHub plugins for interop with AWS start to take longer and longer to be resolved. Then maybe one day they change the terms of service, and it's no longer allowed to develop GitHub plugins which compete with Azure. Then they release an update to VSCode which uses deep learning for code completion. On Windows it uses a new DX12-powered subsystem which makes it fast and responsive, while on Mac and Linux it falls back to a single-threaded solution which makes the whole application feel laggy.

In a scenario like that, it would be in principal possible to fork VSCode and make a more platorm-agnostic version, but how realistic is it that an individual, or even a small team will be able to keep up with a large corporation which seeks to make such an effort less successful.

Open source software is great, but if Microsoft owns the governance of those projects, and the up-streams and down-streams, they still have a lot of power over them.

[manigandham]

Tooling is commodity now. If they don't make tools that run well on other platforms then other vendors step in to fill the demand, or they just wont have the demand in the first place and they lose mindshare anyway.

This is what happened with Java, Go and Javascript growing rapidly while .NET took a long time to get out of legacy/desktop phase, partly because the tooling was fantastic but isolated to their own Windows platform. They've learned their lesson and have realized there are better businesses by providing the compute and making it easy to use with free and plentiful tools.

[sephoric]

Your scenario sounds not only plausible but highly likely. Especially the point about individuals or other principle-driven organizations being relatively unable to reproduce the closed-source advantages that they could tie into open source projects to make them significantly more useful on MS-blessed platforms and systems. This is all a very real possibility.

[JohnL4]

One assumes Amazon & Google both see that possibility and are developing some in-house expertise on those projects.

[sod]

But maybe that history is also a strength. The typescript developers never extend the capabilites of the language, just add types. The only exception being decorators, that was a deal with angular so they don't have to invent their own language for angular2 and can build dependency injection on it by typescript exposing the types to the runtime. But decorators are stil buried behind an experimental flag.

[skohan]

You've explained some of the strengths of TypeScript, but I fail to see the argument for how this is evidence that it's somehow a good thing that Microsoft has a history of being quite a bad actor in the software industry.

[sephoric]

TypeScript has other features such as Enums that don't exist in JavaScript but aren't pure type annotations either. It transforms into very clever bidirectional map tables.

[jcmoscon]

Yes, and I will start looking into azure because of this same amazing feeling I'm having with VS code and typescript.

[nwsm]

Definitely look into it, but it isn't nearly as robust as AWS. Automation/DevOps and data streaming/processing are some lacking areas.

Fine if you just need PaaS app + RDB though.

[h1d]

The interface is astonishingly Windows'ish with millions of knobs to turn and not as stable as you want. (Resource usage metrics returned errors for a while on me.)

You will need time to get used to it. I even use AWS for a Windows instance.

[sephoric]

If it's as cheap and powerful as AWS then I'm on board too. But I doubt it is, Amazon's got it down to an intricate science that seems like it can't be beat.

[WorldMaker]

Depending on specifics (obviously), Azure is quite competitive with Amazon on pricing, and extremely competitive on "power". Your mileage will of course vary, but the interesting thing about Azure versus AWS is (surprising to some) Azure tends to use more "open standards" versus AWS' proprietary solutions. (Two examples off the top of my head: Azure supports Docker and Kubernetes directly rather than the Elastic TLAs' own in house container models and container orchestrators. Azure's most used in-memory cache is Redis.)

[chubot]

This is not new -- Steve Ballmer understood this viscerally (ahem) over 10 years ago:

https://www.youtube.com/watch?v=Vhh_GeBPOhs

Granted, they weren't releasing much open source then, but it was all free to use, and the quality was far above open source alternatives (e.g. think the Visual Studio debugger vs. GDB wrappers).

I think they just naturally figured out that there's zero advantage to keeping developer tools closed source.

[Jach]

MS has long been about "Developers! Developers! Developers!" But these days they're about more than just Windows developers shipping native closed source applications.

[h1d]

Yet Visual Studio (not the Code) is still a payware with multiple editions.

[manigandham]

You can build anything with the free community edition and they keep down-shifting previously enterprise features with every major version.

[evilduck]

It's probably multi-faceted. Part of me thinks it's just something they use internally extensively and that branching out to the public means they can easily hire talent to work on their own projects. It's also probably an effort to stay relevant and make amends with web developers, who have long held them in low regard.

And yeah, Azure is a booming business for them. VSCode has a bunch of first-party extensions that reduce friction for working on their platform.

[fooey]

Microsoft's tooling is fantastic

Trying to work with other databases after using SQL Studio is incredibly frustrating

[alasdair_]

>I can't see what else they could be trying to do.

https://en.wikipedia.org/wiki/Visual_J%2B%2B

Microsoft does the same thing over and over - "embrace" a technology, "extend" it by adding some extra stuff to it that happens to work best on Windows then "extinguish" the tech once people are locked in.

Also see: Internet Explorer or Kerberos or Office document interoperability or AIM (messenger) or half a dozen other things.

[DigitalSea]

It appears the tide is changing and what was once hated upon by many in the JS and front-end community, has now become cool and a tonne of projects are migrating. Another project migrating to TypeScript is the Aurelia Javascript Framework for its next version coming out later in 2019.

It's funny because I remember when Angular 2 was announced and that it would be written completely in TypeScript, they copped a lot of backlash for it, but it appears to have been a good move.

I exclusively have been writing in TypeScript for about 3 years now and it's crazy how good it actually is, especially for distributed teams in different time zones. The code is self-documenting and the number of silly mistakes being committed into our codebase has dramatically been reduced, combined with solid unit tests, we haven't really had a code level bug in what feels like months, browser bugs on the other hand...

My favourite thing about TS besides the types and interfaces is the compiler. I no longer have to use transpilers like Babel anymore because TypeScript handles compiling to many different module formats and targets. Back when I used Babel, it felt like pulling teeth because of the different plugins and packages you had to install and configure to use.

I find it really hard to use anything other than TypeScript now, it is simply too good.

[lhorie]

I'd argue that porting from JS to TS is a very different beast than porting from Flow to TS.

I've ported code from JS to Flow and could say the benefits are similar to those of porting from JS to TS.

The most relevant part in this article IMHO is the conclusion:

> things like a strong community and availability of type definitions are more important because weak type inference can be solved by "handholding" the type checker a bit more.

I think it's important to highlight that this may be true of his project but not necessarily yours or mine.

Flow's type inference provides a much deeper level of confidence than TS with far less effort, for example, typing only the public interface of a module is often enough to surface type mismatch errors several functions deep within the module. In TS, you'd have to type every function signature to get the same level of confidence.

What worries me about flow is reflected in the comment from the facebook engineer linked from the article: it seems the flow team is focusing heavily on facebook-scale performance at the expense of most every other aspect of the project. A while back, the existential operator was quietly deprecated in the name of perf, and lately some updates have been of questionable soundness, e.g.

https://flow.org/try/#0GYVwdgxgLglg9mABAdxFAFAQwFyIPIBGAVgKb... (compared to http://www.typescriptlang.org/play/#src=function%20wut(a%3A%... )

[brett40324]

> In TS, you'd have to type every function signature to get the same level of confidence.

I don't disagree, but isn't this the point? That by typing every function you can reliably have confidence in parameter types and return value types, and if your program is able to throw a type error on build, then it should and alert the developer that they're not logically correct in their implementation.

[lhorie]

My point is mostly that you can get away with explicitly typing less things in flow and still get similar levels of coverage. For example, consider this example:

    export function formatTime(time: Date) {
      return digitize(time.getHours()) + ':' + digitize(time.getMinutes());
    }
    function digitize(n) {
      return ('0' + n.toStirng()).substring(-2);
    }

Just a single type declaration is enough to let Flow catch the typo here. In TS, you'd also have to write the argument types for `digitize`. Importantly, if you wanted to explicitly add arg types for `digitize` w/ Flow, your editor can tell you what they are supposed to be.

[z3t4]

FLow seem to be better at inferring types. example:

    function foo(n) {
          return n*2;
    }
    
    foo("bar");

[z3t4]

Object seem to be any object (any type) in both Flow and TypeScript, if you change it to string, both Flow and TypeScript will give an error.

[mikewhy]

> Even if I have been writing code with Java / C# for nearly a decade , nothing has come close to Typescript in terms of productivity,flexibility and confidence.

TypeScript is, by far, my favorite type system. I love structural typing. I love conditional types (ReturnType<T>). I love things like `keyof T`. I love how good it's inference system is. I love how I can still use it in a JS file and still get type checking with JSDoc.

I tried out Dart over the holidays and it felt like a major step backwards. Seriously, hats off to the developers.

[funkaster]

> if I have been writing code with Java / C# for nearly a decade , nothing has come close to Typescript in terms of productivity,flexibility and confidence

I can completely relate. To me the greatest thing is the tooling around it. Using tide[0] on even plain js codebase is just amazing.

I really wish ruby had a TypeRuby compiler (to regular ruby). I know about crystal, but I still want regular Ruby, just with a type checker at compile time, not runtime.

[0]: https://github.com/ananthakumaran/tide

[tybit]

> It's well know that if you start using C# , your entire stack will generally be MS based...(SQL Server, Azure etc... )

That’s only because of Microsoft fanboys nowadays, .NET core is a pleasure to use on Linux and AWS with a variety of databases etc

[skrebbel]

Yup, it's ridiculous cargo cultism from mediocre C# programmers. There's nothing about C# that forces you into MS's ecosystem.

In 2014, well before Microsoft's dotnetcore oss adventure, I ran the dev team at a startup. Our entire backend was C#. Our devs used the OS of their preference, and so we had Mac, Windows and Linux. Xamarin Studio is (was?) a remarkably decent IDE for something so niche.

We hosted it in Docker (bad call, it was way too new then) on Mono (great call, it Just Worked), on Linux. Data in Postgres. All of this was as easy as doing the same with eg JS or Java (and arguably easier than eg Ruby because C# has a proper cross platform dependency story).

There's nothing about C# that forces you to use SQL Server or Azure. Absolutely nothing.

[mirekrusin]

If you did js->ts, that's not "exact same job", is it? He describes flow->ts and highlights differences between the two.

[romanovcode]

> It's well know that if you start using C# , your entire stack will generally be MS based...(SQL Server, Azure etc... )

This is very not true. For the past 2 years or so of using C# I never used MSSQL, Azure or even Windows.

[iamaelephant]

> It's well know that if you start using C# , your entire stack will generally be MS based...(SQL Server, Azure etc... )

It may be "well know" but it's entirely untrue.

[munchor]

That's awesome! Did you convert from Flow or just plain JS? I think the experience is much different when converting from Flow vs converting from JS. When coming from pure JavaScript, you do indeed become much more confident and flexible around the code. When you come from Flow, the differences are much more subtle as I described in the article.

[matchbok]

Yup. I will never start a new project in plain JS ever again.

[nojvek]

To be fair, pure js with types as jsdoc comments that typescript handles just fine is a great way to write code.

No transpiration needed for node modules. No source maps, it’s same old plain JS that’s nicely checked by typescript.

[no1youknowz]

I went from jQuery (inc libs) and < ES5, to VueJS (components) and ES6.

It was such a big jump, after 8 months of it now. I am so much more productive than I was before. It's just not funny.

If I did the same as you. Going from JS to TS, what kind of experience (from there on in) should I be looking at?

[com2kid]

IMHO the largest difference is the amount of time you save hunting down stupid issues. e.g. no more spending 3 hours fixing a typo.

Also, code is much more manageable, and refactoring is tons easier.

With enough Babel plugins, you can get ESNext functionality that does whatever you want (some of those early stage proposals are really cool! They might go away tomorrow, but hey, so cool!), so Typescript's old advantage of offering more language features is kinda nullified.

In the end, I started writing the later part of my current project in Typescript, and I much more enjoy working on that part of the code than the earlier parts.

[sonnyblarney]

TS takes one day to get going, which is one of the best things about it.

Stick to the 'basics' of TS, which are super general programming syntax structures and idioms - there's really nothing new you'll come across (maybe unions?) - so it's easy.

Then you can try some of the trickier things but frankly we don't use them that much.

You'll be up and running pretty quickly because you can mix your 'new' TS modules with old-school JS code no problem.

And then go from there.

I like TS because it's not some big new fancy paradigm shift: it's just typing, some other pragmatic things, and it works pretty well, very quickly.

It's the only tech I will actively evangelize as being 'the thing you need if you use JS' type thing.

[knocte]

> It's well know that if you start using C# , your entire stack will generally be MS based...(SQL Server, Azure etc... )

Why the fuck...?

I love using Linux+PostgreSQL with F#, and deploying to AWS.

> Even if I have been writing code with Java / C# for nearly a decade , nothing has come close to Typescript in terms of productivity,flexibility and confidence.

Disagree. After doing JS & Java & C# & Perl & F# & TS (& a bit of others such as C, C++, Python), I think TS is just a giant patch to a language that is broken by design. And a patch is just a patch. Just fucking migrate to a decent language already! (e.g. F# or Rust)

[czechdeveloper]

From my point of view, they have just great integration together, but but nothing really forces you to use them. Original post sounded like you are being forced into it.