Ben Crowder

Learning WebAssembly, part 2

Continuing on with the AssemblyScript concepts chapter.


No any or undefined — interesting. And good, I think. But no union types yet? A little sad.

Okay, so module imports and exports are the main way (possibly the only way) the host communicates with the Wasm script. I knew about exports but didn’t know about declare and module imports. Nice.

The tree-shaking approach to compiling is interesting — dead code doesn’t get type checked, for example.


Not as much type inference as TypeScript. Good to know.

Oh, interesting: WebAssembly has distinct operations for signed and unsigned comparisons. (gt_s vs. gt_u, for example.) Also, == === ===. (Couldn’t resist. But yes, given that the basic types aren’t nullable etc., makes sense that == is also doing strict equality.)

Standard library

I think the reason I like reading through standard library docs is the same reason I like reading through dictionaries — both open up a world of possibilities. And each time I go exploring, I find something new. Need to do more of both.

I like that the low-level WebAssembly instructions are available to AssemblyScript.

Nice, there’s manual memory management when you need it.

StaticArrays for C-like arrays with better performance, got it.

The string considerations section was interesting.

Implementation status

Some drama with WASI and the component model. I don’t know enough about the situation to comment, but I hope things get sorted out in a way that’s good for standards and the web platform.

Ah, there aren’t closures, Promises, exceptions, or rest parameters in AssemblyScript. That’s very good to know.

Using the runtime

A few different runtime options, including support for a custom runtime. Interesting.

Reading about the memory layout was fun. Reminds me of writing C twenty-some years ago. I need to come up with a low-level project to work on sometime.

And that’s a wrap on the documentation. I’ve decided that my learning project for AssemblyScript will be a small convex hull implementation. Notes on that coming soon!

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