There are many blogs on the internet, but the best ones I encounter are all interactive. They have code snippets that you can run, modify, and see the results right there. They have quizzes, exercises, and interactive diagrams. They are not just a wall of text, they are a playground where you can learn by doing.

I tried to write my articles interactively, but it was just too much effort per article, so I decided to design a simple declarative language defining the components and their interactions with each other. The result is DCL(Declarative Component Language) and Devy, a blog engine that renders articles written in DCL.

Devy is implemented as a Pandoc filter using pandoc_ast crate. It reads a markdown file, detects DCL snippets written as code blocks, generates the necessary Javascript code for the interactions and renders the article as a static HTML file.

Below, you can see a Devy in action!

Also, there is an introduction to devy using devy article on my blog, if you're interesting in seeing Devy in action!

DCL is pretty small for now, the only components are text-input, text-area, paragraph, and radio. Each component has a name, type, and value, where the value can be a constant or a function of the values of other components. The components can be connected, so that when a component changes, the connected components are updated as well.

Below, you can see a simple example of run-length encoding used in Devy. The first code block is marked as a script, meaning that it will be executed in the browser within a <script> tag, show means that the code will be displayed in the HTML as a code block. The second code block is marked as dcl, meaning that it will be parsed by Devy and rendered as a component.

```js  {#runLengthEncode .script .show}

const runLengthEncode = (str) => {
    const result = [];

    let currentChar = str[0];
    let currentCount = 1;
    let i = 0

    while(i < str.length) {
        if(str[i] === currentChar) {
            currentCount++;
        } else {
            result.push([currentChar, currentCount]);
            currentChar = str[i];
            currentCount = 1;
        }
        i++;
    }

    result.push([currentChar, currentCount]);

    return result.map(([c, n]) => c + n).join("");
}
```

```dcl
x : text-input := aaabbbcccc
y : text-area := x => runLengthEncode(x)
```

The result of the dcl block is as follows:

<input type="text"  id="x"  value="aaabbbcccc" ></input>
<script>
    document.getElementById("x").addEventListener('input', function(event) {
    document.getElementById("y").value = runLengthEncode(document.getElementById("x").value)
});
</script>
<textarea id="y" ></textarea>

I plan to add more components and features to DCL in the future, such as quizzes, diagrams, and more. The project is all need-based for now, I'll add features as I need them. in my articles. If you want to be involved, just open an issue or a PR!

• Text Input
• Text Area
• Paragraph
• Radio
• Checkbox
• Range
• Button
• Switch
• Custom Styling
• Custom Components(Allows reusability of CDL blocks)
• Class Names for Components
• Javascript Aware Syntax Transformation

• Copy Button for Code Blocks
• Line numbers for Code Blocks
  • Line numbers with offsets
  • Line numbers for non-js code blocks
• Code Running/Echo for Code Blocks(Javascript)
• Code Running/Echo for Code Blocks(Other languages)
• File names in Code Blocks

• Mermaid
  • Mermaid with Default Animations
  • Extended Mermaid with Animations
  • Custom Styling
• D2
• Inline JSX Support