Every technology created at Facebook is meant for internal use. The wider community then goes through the pain of making it usable. Microsoft's mission on the other hand is pleasing developers hence VS Code and TS.
EDIT: haha here it is https://github.com/facebook/flow/issues/4785
Nobody should be using Flow.
Assignment is still there though (ie you can still assign a `Cat[]` to an `Animal[]` and push a `new Dog()` into it).
class Animal {}
class Cat extends Animal { meow() {} }
class Dog extends Animal { woof() {} }
function foo(animals: Animal[]) {
animals.push(new Dog)
}
const cats: Cat[] = [new Cat];
foo(cats);
When you mentioned "covariant param passing" I assumed you were referring to the long-lasting issue about callbacks, hence my original comment mentioning that that issue has been fixed. It's not useful to differentiate between "assigning a value to a variable of a certain type" and "passing a value to a function parameter of a certain type" because those are identical.
(I don't ever have to have any `any` in my ReasonML code, but it was unavoidable with Flow.)
1. https://reasonml.github.io/blog/2017/09/08/messenger-50-reas...
2. https://github.com/facebook/flow/issues?utf8=&q=is%3Aissue+i...
Microsoft has paying customers who are devs, and FB doesn't. That explains a lot.
[1]: https://www.bloomberg.com/company/press/open-source-at-bloom...
Over the time I began more and more appreciate Microsoft's "boringness" (which is debatable itself) because their tools are real products, not marketing tools for developers. What matters more for serious project is tools quality, not few hot CS ideas loosely implemented on a knee.
Go was created to solve Google's problems with C++ and engineering at scale
The fact that TypeScript wasn't created to solve a big issue internally at Microsoft is exactly what makes me skeptical of it and personally I view it as a trojan horse, just like VSCode. Sure, today it is done for benevolent reasons, maybe, but what about tomorrow? What if that trillion dollar market cap starts tanking? Then The benevolent VSCode and TypeScript ecosystems become levers to pull in the great big machine.
I would almost feel better if I knew it's stated explicit purpose upfront and what Microsoft's long term goals to monetize the ecosystem/platform were, because then I know what I am signing up for.
AFAIK it was, the issue was the poor quality of Javascript development they were having and their inability to really get good tooling and static analysis. Then it kind of exploded as other people said "That's cool" and they then pushed it out as open source so that if they did need to let it go it wouldn't be totally dead in the water.
VSCode was started to see if they could build a good web application for development. Portions of it directly power a number of tools of Azure (on portal.azure.com), portions of it also directly powered the Dev Tools inside IE10+ and Edge "Classic". Bundling the web app into an Electron container after it had already paid for its own engineering efforts several times over as reusable sets of components for multiple large web apps Microsoft needed hardly seems like a "trojan horse" to me.
Technology is a stretched term for ReasonML. It's a simple syntactic sugar for OCaml. It uses standard OCaml compiler and standard JS transpilers, like js_of_ocaml and bucketscript.