Flow

A typed dialect of JavaScript.

[Flow @flowtype]

@nicu_tsx @jaredforsyth https://t.co/C73SPFQKkl

[Flow @flowtype]

Flow is now written in Rust 🦀

The migration from OCaml to Rust brought up to 2x faster type-checking on large codebases.

[Flow @flowtype]

The Rust port is just the start. Flow in 2026 isn't like you remember: https://t.co/mjquUVDJco

[Flow @flowtype]

Flow is now written in Rust 🦀

The migration from OCaml to Rust brought up to 2x faster type-checking on large codebases.

[Flow @flowtype]

Most of the Rust port was done by a single engineer over ~8 months, while the rest of the team kept shipping features: no code freeze.

Read the full story: https://t.co/9hVjtn6GFS

[Flow @flowtype]

@justboriss Yes, you can fix it by changing the code. If only there was a tool that would point out the problem in the first place - so you knew you had to make the fix 🤔

[Flow @flowtype]

Crashes at runtime - but TypeScript accepts it: zero errors under strict. Can you spot the bug?

[Flow @flowtype]

@vpetryniak Doesn't seem like a good assumption 😬

[Flow @flowtype]

@jaydenfyi Exactly, better to have your type-checker actually enforce you're doing the right thing and prevent your app from crashing! The actual Flow error message is longer and describes:
- Either make `Array<string>` and `Array<LogLine>` the same
- Or make array a `ReadonlyArray`

[Flow @flowtype]

Flow catches the crash before you ship it.

More examples where Flow is safer: https://t.co/80ykNpBOFE

[Flow @flowtype]

TypeScript lets you pass Array<string> where Array<string | Error> is expected, so the function pushes an Error to your string array. Flow rejects it.

TS Playground, 0 errors: https://t.co/4XzG9wnPml

Flow Playground, rejects with an error: https://t.co/dKqUEDKEme

[Seb ⚛️ ThisWeekInReact.com @sebastienlorber]

👀 Is this Flow, or TypeScript?

Is Flow coming back?

- Flow syntax aligns with TypeScript
- Flow has pattern matching
- Useful React hooks/component/renders syntax
- Compiler has been recently ported to Rust

I'll keep an eye on it for you, but this is promising!

[Flow @flowtype]

JavaScript Pattern Matching with `match`, available now: https://t.co/ipDMUSoyMk

[Flow @flowtype]

Flow for TypeScript Users in 2026: 20+ side-by-side comparisons, verified against TypeScript 6.0.3 with 'strict' enabled:
https://t.co/uek156i5jP

[Flow @flowtype]

If your "Flow vs TypeScript" take is from 2021, it's out of date. Flow looks like TypeScript now - but it has pattern matching and React component syntax, while catching runtime crashes TypeScript waves through. Examples below. 👇

[Flow @flowtype]

Another: TypeScript only validates the signature of a type-guard, not the body.
Flow validates the body and rejects predicates that lie about what they check.

[Flow @flowtype]

SWC has added support for Flow: https://t.co/PvFsh0QHaX