# Wenyan-rs

A bytecode interpreter for [Wenyan-lang](https://github.com/wenyan-lang/wenyan).

## Usage

```bash
wyr path/to/filename.wy
```

## Examples

```bash
吾有一術 名之曰「階乘」 欲行是術 必先得一數 曰「甲」 乃行是術曰
 若「甲」等於一者。
  乃得「甲」
 若非
  減「甲」以一名之曰「乙」
  施「階乘」於「乙」名之曰「丙」
  乘「丙」以「甲」。名之曰「丁」
  乃得「丁」
 云云
是謂「階乘」之術也

施「階乘」於五書之
```

Output:

```bash
120
```

This project are still work in progress, many features are not implemented yet. You can see more supported examples in [examples](./tests/inputs/) folder.

## Differences

The [Online IDE](https://ide.wy-lang.org/) has many friendly enhances, some of my rules may be more strict for ease of implementation.

Variable need to be wrapped with single quote.

```bash
吾有一數曰五名之曰「甲」 // ✅
吾有一數曰五名之曰甲 // ❌

昔之「甲」者今其是矣 // ✅
昔之甲者今其是矣 // ❌
```

Disable partially define variables.

```bash
吾有二數曰五曰六  // ✅
吾有二數曰五曰六名之曰「甲」名之曰「乙」 // ✅
吾有二數曰五曰六名之曰「甲」 // ❌ 
```

Has implicit block scope.

```bash
吾有一數曰十名之曰「甲」
若陽者
  吾有一數曰一名之曰「甲」
  加「甲」以五書之
云云
加「甲」以五書之
```

Output vs Online IDE:

```diff
-6
-6
+6
+15
```

Boolean algebra statement always gets boolean.

```bash
吾有一數曰五名之曰「甲」
吾有一數曰六名之曰「乙」
夫「甲」「乙」中有陽乎
書之

吾有一數曰五名之曰「甲」
吾有一數曰六名之曰「乙」
夫「甲」「乙」中無陰乎
書之
```

Output vs Online IDE:

```diff
-5
-6
+true
+true
```

Treats single [data](https://wy-lang.org/spec.html#data) as expression and will be pushed into stack.

```bash
吾有一數曰五名之曰「甲」
「甲」書之
「「黃河流水鳴濺濺」」書之
```

Output vs Online IDE

```diff
+5
+黃河流水鳴濺濺
```

Treats '也' as kind of whitespace, you can use it to make code more readable, but can't use it as close of block.

```bash

Function will be added into stack, and "書之" will drain values produced by current function.

```bash
吾有一數曰五名之曰「甲」
吾有一術名之曰「你好」是術曰
夫「「世界，你好」」書之
是謂 「你好」 之術也

施「你好」
```

After `夫「「世界，你好」」書之`, The stack will be:

```bash
[2] <fn 你好>
[1] Value::Number(5)
[0] <global context> 
```

When function `你好` returns, the stack will be:

```bash
[1] Value::Number(5)
[0] <global context> 
```

Take advantage of our own virtual machine, It has ability to report more kind of runtime errors.

```bash
吾有二言曰『你』曰『好』名之曰「甲」名之曰「乙」 
減「甲」以「乙」書之
```

Output:

```bash
[line 2] errors: two string can only be added
```

## Future Work

There are still many features not implemented! Part of them are listed in [this issue](https://github.com/mysteryven/wenyan-rs/issues/1).

## Credits

- [Crafting Interpreters](http://craftinginterpreters.com/)
- [lox-rs](https://github.com/Darksecond/lox)

## License

[MIT.](./LICENSE)