Skew wasn't just a little bit faster than TypeScript.
According to Evan Wallace (former Figma CTO), it was 1.5x to 2x faster due to better optimizations enabled by stricter type system.
According to Evan Wallace (former Figma CTO), it was 1.5x to 2x faster due to better optimizations enabled by stricter type system.
It's also what JITers like V8 internally do, you'll get major performance hits if you do weird dynamic things.
If you can leave the type system in place, then you could move toward an ML-style type system and see massive improvements within strictly-typed parts of the code as you'd only need type guards and inline caches at the boundaries of the strictly-typed code.
Only if your code was pure number crunching.
Normal code can't just go through some belt tightening to become WASM/asm.js code. Compiling it down that way is very different from making the control flow more understandable to the optimizer.
My guess is mainly the integer optimizations. And I guess making sure that functions are always called with the same argument types. The other optimizations is already done by the JITs.
It's probably not as simple as that. If hotpaths are optimized, the 2x advantage is quite likely to vanish.
But then one could say - well, you're forced to write optimized JS in several places and that impacts readability. Sure, but the trade off was to use an entirely new compile-to-js language with less tooling support and mindshare. It seems now that it wasn't worth it. The blog post sort of sugarcoats this contentious previous technical choice.
While I'm not going to debate this particular instance, I would caution against assuming all moves (with or without blog posts written about them) are indeed the best and wisest moves that could be made given the situation.
It's incredibly hard to look at our industry at large and declare that teams/companies are doing the best thing they can at any given point (where "best" is defined here as the most prudent thing, all things considered).
I wonder if it’s possible to limit one’s use of typescript to just the subset that gives that same performance…