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Facebook Launches Flow, Static Type Checker for JavaScript

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Re: Facebook Launches Flow, Static Type Checker for JavaScript

#151

Post by themartorana »

lhnz wrote: post #133
kulkarnic wrote: post #127

Earlier quoted context omitted.

Is this a serious post, or are you being sarcastic? I honestly can't tell. JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with. I can certainly see being stuck with Javascript (just like we're stuck with the x86 instruction set even if simpler alternatives exist), but I'm not sure it's some…

You are right that there are some problems in the language. However, I would rethink your argument based on the rapid development of the language over the last 5 years. For example, yes callbacks were very messy but very soon we will have generators. And, yes, the scoping was nasty but soon we will have the 'let' keyword. I cannot remember where I read it, but I do also remember seeing a talk about some proposals to…

There's momentum, and that's the why. Imagine trying to get Apple, MS, Google, Mozilla, et al to agree on a JavaScript replacement that was rolled out at the same time.

Then deal with the 5-10 years or so legacy browsers hang around with significant market share.

JS was anointed long ago, and if we knew then what we knew now, maybe it wouldn't have been so? I remember DHTML and how silly it was and how it was just a toy and BOOM! Ajax.

So here we are. Every browser supports it, none could agree to change, so we deal with what we got. Better tools are better than nothing.

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#152

Post by ori_b »

kulkarnic wrote: post #127
DigitalSea wrote: post #39

What a great tool. Facebook are absolutely killing with the last year or so with all of their open source contributions and releases. First HHVM, Haxl, React.js (amongst other things) and now Flow, this is fantastic. I am really liking how companies like Facebook & Google are concentrating their efforts on the web language of the future: Javascript. The support for JSX alone is a MASSIVE feature (expected given React…

Is this a serious post, or are you being sarcastic? I honestly can't tell. JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with. I can certainly see being stuck with Javascript (just like we're stuck with the x86 instruction set even if simpler alternatives exist), but I'm not sure it's some…

> JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with.

You're looking at it from a technical perspective, and from a technical perspective JS is an awful language.

It may be a turd. But it's the only sandboxed-by-default, zero-install, reasonably-fast, free, preinstalled-on-every-machine turd that we have.

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#153

Post by ori_b »

kulkarnic wrote: post #127
DigitalSea wrote: post #39

What a great tool. Facebook are absolutely killing with the last year or so with all of their open source contributions and releases. First HHVM, Haxl, React.js (amongst other things) and now Flow, this is fantastic. I am really liking how companies like Facebook & Google are concentrating their efforts on the web language of the future: Javascript. The support for JSX alone is a MASSIVE feature (expected given React…

Is this a serious post, or are you being sarcastic? I honestly can't tell. JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with. I can certainly see being stuck with Javascript (just like we're stuck with the x86 instruction set even if simpler alternatives exist), but I'm not sure it's some…

> JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with.

You're looking at it from a technical perspective, and from a technical perspective JS is an awful language.

It may be a turd. But it's the only sandboxed-by-default, zero-install, reasonably-fast, free, preinstalled-on-every-machine turd that we have.

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#154

Post by ori_b »

kulkarnic wrote: post #127
DigitalSea wrote: post #39

What a great tool. Facebook are absolutely killing with the last year or so with all of their open source contributions and releases. First HHVM, Haxl, React.js (amongst other things) and now Flow, this is fantastic. I am really liking how companies like Facebook & Google are concentrating their efforts on the web language of the future: Javascript. The support for JSX alone is a MASSIVE feature (expected given React…

Is this a serious post, or are you being sarcastic? I honestly can't tell. JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with. I can certainly see being stuck with Javascript (just like we're stuck with the x86 instruction set even if simpler alternatives exist), but I'm not sure it's some…

> JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with.

You're looking at it from a technical perspective, and from a technical perspective JS is an awful language.

It may be a turd. But it's the only sandboxed-by-default, zero-install, reasonably-fast, free, preinstalled-on-every-machine turd that we have.

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#155

Post by ori_b »

kulkarnic wrote: post #127
DigitalSea wrote: post #39

What a great tool. Facebook are absolutely killing with the last year or so with all of their open source contributions and releases. First HHVM, Haxl, React.js (amongst other things) and now Flow, this is fantastic. I am really liking how companies like Facebook & Google are concentrating their efforts on the web language of the future: Javascript. The support for JSX alone is a MASSIVE feature (expected given React…

Is this a serious post, or are you being sarcastic? I honestly can't tell. JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with. I can certainly see being stuck with Javascript (just like we're stuck with the x86 instruction set even if simpler alternatives exist), but I'm not sure it's some…

> JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with.

You're looking at it from a technical perspective, and from a technical perspective JS is an awful language.

It may be a turd. But it's the only sandboxed-by-default, zero-install, reasonably-fast, free, preinstalled-on-every-machine turd that we have.

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#156

Post by gregwebs »

Even without the flow analysis and better typing, incremental compilation is a huge improvement over TypeScript, which re-parses type declarations on every compilation. That quickly leads to large compile times when you have type definitions for third-party components (even though you may only be using one definition in the file, the entire definition is parsed).

The existing available definitions from the DefinitelyTyped project is a huge productivity booster. Apparently Flow also has similar .d.flow files, but it will probably be a while until they exist for common projects.

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#157

Post by warfangle »

spion wrote: post #136
kulkarnic wrote: post #127

Earlier quoted context omitted.

Is this a serious post, or are you being sarcastic? I honestly can't tell. JS the language of the future? Why? It has probably the worst gotchas of any language I've coded in, it's verbose, and weird scoping. Nor is it especially nice to optimize for/with. I can certainly see being stuck with Javascript (just like we're stuck with the x86 instruction set even if simpler alternatives exist), but I'm not sure it's some…

ES6 adds lambdas, destructing assignment, default/rest/ spread arguments and template strings - all of those reduce verbosity. And there is `let` which has a "normal" scope, although I'm not really sure it needs that. Additionally, generators let you use normal control flow constructs for IO, if you prefer that to FP. While its no Haskell, it certainly isn't much more verbose than other dynamic languages anymore. And…

We've got parallelism in the browser (sorta) with webworkers.

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#158

Post by McKayDavis »

gregwebs wrote: post #156

Even without the flow analysis and better typing, incremental compilation is a huge improvement over TypeScript, which re-parses type declarations on every compilation. That quickly leads to large compile times when you have type definitions for third-party components (even though you may only be using one definition in the file, the entire definition is parsed). The existing available definitions from the Definitely…

I was going to comment that this sounds like an opportunity to get mileage out of the huge amount of typeinfo already provided by DefinitelyTyped by building a tool to convert .d.ts into .d.flow files.

After investigating this thought, it looks like this already at the top of the list for future plans for Flow:

http://flowtype.org/docs/coming-soon.html

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#159

Post by avik »

void_star wrote: post #53

This is really cool. Does anyone have pointers to relevant papers that inspired/influenced their type system?

The implementation is heavily influenced by Pottier's work on subtyping + inference. https://hal.inria.fr/file/index/docid/73205/filename/RR-3483...

Also, some techniques from Typed Racket (occurrence typing): http://www.ccs.neu.edu/racket/pubs/popl08-thf.pdf

Many other papers have influenced the design in some way or the other. For example, Abadi/Cardelli's theory of objects.

Re: Facebook Launches Flow, Static Type Checker for JavaScript

#160

Post by avik »

discreteevent wrote: post #135
ep103 wrote: post #68

This looks like such a better step in the right direction than than the types of tools MS and Google have been putting out. Dynamically discerning the underlying code, and allowing optional type annotation works _with_ javascript, as opposed to attempting to turn js into a completely different (and weakened) language. That said, I am curious what solutions this solves that isn't already solved by enforcing good code…

The main benefit of types for me is not correctness but documentation and tooling. It's fine not to have types in code I write myself or with one or two others. But if I have to deal with a large codebase that I wasn't involved in writing then types make it so much quicker to understand. Just being able to quickly find all references to a type or all a method's call sites makes it possible to "reverse engineer" the d…

We have some basic editor support, more is coming soon. Flow exposes several commands that are useful through an editor, like type-at-pos (give it a position, it gives you back the inferred type), suggest (give it a file, it dumps out an annotated file), autocomplete (gives you suggestions at a given position), etc. Also, we require annotations at module boundaries, so you're modules are going to have well-typed interfaces that serve well for both documentation and stability.
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