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Comment by nathan_f77 | Hacker News Reader

* TypeScript has larger community.

That's a very good reason. I wish there were more community-provided types for flow. I think Immutable.js has only just fixed the last issues, but that's really been bugging me for the last few months. ("no default export" and "isEquals".)

* Flow requires Babel.

Not a huge deal for me, since React Native already requires Babel, and I personally like working with Babel. I use a number of Babel plugins, such as "transform-decorators-legacy" and "module-resolver".

* Flow is written in OCaml. It could probably make it more difficult to install than TypeScript.

Not at all, installation was very quick and easy. You can use either npm or Homebrew.

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> I wish there were more community-provided types for flow.

One technical limitation that complicate contributions to the flow-typed repository is that there is no way of writing typings that depend on other libraries' types [1]. For instance, flow-typed has a library definition for `rxjs`, but it is not possible to e.g. add a definition for `redux-observable` that reuses the RxJS `Observable<T>` type, because there is no way to express that the typings of `redux-observable` neeed the ones of `rxjs` to function. So typings for such closely related libraries tend to not exist in flow-typed.

To work around this problem, some libraries like styled-components require you to manually include the library definition files it requires in your `.flowconfig` [2], but this is a rather hacky workaround.

[1]: https://github.com/flowtype/flow-typed/issues/16

[2]: https://github.com/styled-components/styled-components/blob/...

Oh, that's a shame. I've spent the last few hours reading up on RxJS, and I just finished watching this talk on redux-observable [1], so I'm totally ready to dive in and rewrite some parts of my app. I was actually about to rewrite it with redux-saga, but I've decided that redux-observable and RxJS is far more awesome.

So are you saying that there are no flow types for redux-observable? I guess that's not a deal-breaker, since flow-typed will just generate stubs. Also, it looks like react-observable is a super high level abstraction, so I'm not even going to be writing that much code.

[1] https://www.youtube.com/watch?v=AslncyG8whg&feature=youtu.be

> React Native already requires Babel.

Could you elaborate on that please? Is it impossible to skip Babel when using React Native?

> Not at all. Installation is very fast and easy.

(Last time I checked Flow npm package gives you binaries.)

I'm sure Flow installs fine in "standard" environments, like an OSX laptop. I was thinking about more weird places, like CI servers where you can't fully control the environment. I was burned enough about stuff like that in the past.

Ah, I see. Well, I'm sure it's common enough that you would have no problems getting it running on CircleCI and TravisCI.

Here's the only issue I found, which is now closed: https://github.com/flowtype/flow-typed/issues/247

Sure! I'll just note there are more CI systems than CircleCI and TravisCI. Especially on premise and on older distros.

> Could you elaborate on that please? Is it impossible to skip Babel when using React Native?

Yes, the React Native packager depends on Babel, and uses a react-native preset. When you start a new project, you get this default .babelrc:

    {
      "presets": [
        "react-native-stage-0"
      ]
    }

They basically wrote their own version of webpack, to solve some performance problems and make development as fast as possible.

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