[yjgyhj]

I've used TypeScript, Flow and Elm for making front-end apps. My favourite of the three is by far Elm, even if that was a bit harder to get into (as it's a new language and I didn't know before how to do side-effect free programming).

Flow is definitely a better type system than TS. TS types are "strong" in the same way as Java types. Flow is basically OCaml types, so a similar type system to OCaml, Haskell or Elm (except that you can give things `any` type). I am sure I will chose Flow over TS for that reason.

A ML-type type system (Flow, OCaml, Haskell, Elm, etc) is very powerful in that you can have abstract types, which means you can do basic composition of them. Things like the Maybe or Result monad for instance, which is very useful (and simple).

Typescript on the other hand let's you use the basic JS types, but it's not as extensible.

[paavohtl]

Do you have any examples to back up your claims? I don't think Flow's type system is more advanced than TypeScript's (which is not Java-like in any way).

What do you mean by "abstract types"? TS's type system is based around structural interfaces, so you're almost always working with non-concrete types.

It also supports discriminated unions, and you can emulate nominal typing with abstract tag properties.

https://www.typescriptlang.org/docs/handbook/advanced-types.... https://basarat.gitbooks.io/typescript/docs/tips/nominalTypi...

[boubiyeah]

This is completely wrong regarding TS. Check out what the last few versions have added, it's solid.