<figcaption><em>WAForth integrated in <ahref="https://mko.re/thurtle/">Thurtle</a>, a <ahref="https://en.wikipedia.org/wiki/Turtle_graphics">turtle graphics</a> programming environment using Forth</em></figcaption>
Besides just-in-time compilation (in a browser or native), WAForth can also be used to compile Forth ahead-of-time.
[`waforthc`](https://github.com/remko/waforth/tree/master/src/waforthc) is a tool that uses WAForth to compile a Forth program into a native executable.
A [simple example](https://github.com/remko/waforth/blob/master/src/web/examples/prompt/prompt.ts) ([CodePen](https://codepen.io/mko-re/pen/gOzzmXZ)) to illustrate starting WAForth, and binding JavaScript functions:
For asynchronous bindings, use `bindAsync` instead of `bind`.
`bindAsync` expects an execution token on the stack, which is
to be called with a success flag after the bound function is called. This is illustrated in [the fetch example](https://github.com/remko/waforth/blob/master/src/web/examples/fetch/fetch.ts):
```typescript
forth.bindAsync("ip?", async () => {
const result = await (
await fetch("https://api.ipify.org?format=json")
).json();
forth.pushString(result.ip);
});
forth.interpret(`
( IP? callback. Called after IP address was received )
Because it is powered by WebAssembly, this extension works both in the desktop version of Visual Studio Code and in [the browser version of Visual Studio Code](https://code.visualstudio.com/docs/editor/vscode-web) (e.g. https://github.dev, https://vscode.dev).
You can also convert the notebook into a lightweight self-contained page using [`wafnb2html`](https://github.com/remko/waforth/tree/master/src/web/notebook).
An example can be seen [here](https://mko.re/wafnb/drawing-with-forth).
Here are some of the goals (and non-goals) of WAForth:
- ✅ **WebAssembly-first**: Implement as much as possible in (raw) WebAssembly. Only call out to JavaScript for functionality that is not available in WebAssembly (I/O, loading compiled WebAssembly code).
- ✅ **Simplicity**: Keep the code as simple and clean as possible. Raw WebAssembly requires more effort to maintain than code in a high level language, so avoid complexity if you can.
- ✅ **Completeness**: Implement a complete (and correct) Forth system, following the [ANS Standard](http://lars.nocrew.org/dpans/dpans.htm), including all [ANS Core words](http://lars.nocrew.org/dpans/dpans6.htm#6.1).
- ❓ **Speed**: If some speed gains can be gotten without paying much in simplicity (e.g. better design of the system, more efficient implementation of words, simple compiler improvements, ...), then I do it. However, generating the most efficient code would require a smart compiler, and a smart compiler would introduce a lot of complexity if implemented in raw WebAssembly, so speed is not an ultimate goal. Although the low level of WebAssembly gives some speed advantages, the design of the system will cause execution to consist almost exclusively of indirect calls to small functions, so there will be languages targeting WebAssembly that run faster.
- ❓ **Binary size**: Since the entire system is written in raw WebAssembly, and since one of the main goals is simplicity, the resulting binary size is naturally quite small (±12k). However, I don't do any special efforts to save bytes here and there in the code (or the generated code) if it makes things more complex.
- ❓ **Ease of use**: Like most Forths, I currently don't do much effort to provide functionality to make Forth programming easy and safe (helpful errors, stacktraces, strict bounds checks, ...). However, the compiler emits debug information to help step through the WebAssembly code of words, and I hope to add more debugging aids to the compiler in the future (if it doesn't add too much complexity)
