The goal is to implement a form of pattern matching that works well in the existing dynamic environment of ECMAScript.
The goal is to find a way to do efficient pattern matching such as using an object tag. JS VMs already have a field for this that is used to tag various kinds of built-in objects.
This tag could be extended to also include a user space range.
| let cache = new Map(); | |
| let pending = new Map(); | |
| function fetchTextSync(url) { | |
| if (cache.has(url)) { | |
| return cache.get(url); | |
| } | |
| if (pending.has(url)) { | |
| throw pending.get(url); | |
| } |
I heard some points of criticism to how React deals with reactivity and it's focus on "purity". It's interesting because there are really two approaches evolving. There's a mutable + change tracking approach and there's an immutability + referential equality testing approach. It's difficult to mix and match them when you build new features on top. So that's why React has been pushing a bit harder on immutability lately to be able to build on top of it. Both have various tradeoffs but others are doing good research in other areas, so we've decided to focus on this direction and see where it leads us.
I did want to address a few points that I didn't see get enough consideration around the tradeoffs. So here's a small brain dump.
"Compiled output results in smaller apps" - E.g. Svelte apps start smaller but the compiler output is 3-4x larger per component than the equivalent VDOM approach. This is mostly due to the code that is usually shared in the VDOM "VM" needs to be inlined into each component. The tr
All libraries have subtle rules that you have to follow for them to work well. Often these are implied and undocumented rules that you have to learn as you go. This is an attempt to document the rules of React renders. Ideally a type system could enforce it.
A number of methods in React are assumed to be "pure".
On classes that's the constructor, getDerivedStateFromProps, shouldComponentUpdate and render.
Snake is a fun game to make as it doesn't require a lot of code (less than 100 lines with all comments removed). This is a basic implementation of the snake game, but it's missing a few things intentionally and they're left as further exploration for the reader.
