Add 2 interactive examples

public/css/global.css

@@ -1,3 +1,22 @@
+/* Iosevka web */
+@font-face {
+    font-family: "Iosevka Fixed Web";
+    font-display: swap;
+    font-weight: 400;
+    font-stretch: normal;
+    font-style: normal;
+    src: url("/Iosevka/Regular.woff2") format("woff2");
+}
+
+@font-face {
+	font-family: 'Iosevka Fixed Web';
+	font-display: swap;
+	font-weight: 700;
+	font-stretch: normal;
+	font-style: normal;
+	src: url('/Iosevka/Bold.woff2') format('woff2');
+}
+
 
 :root {
     --c-bg: #121212;
@@ -49,7 +68,7 @@ body {
 }
 
 pre, code {
-    font-family: Iosevka, 'Fira Code', monospace;
+    font-family: "Iosevka Fixed Web", "Iosevka Nerd Font", Iosevka, monospace;
 }
 
 .button-effect-receiver {

public/css/pages.css

@@ -42,7 +42,7 @@
     padding: 0.5rem 0;
 }
 
-.markdown pre {
+.markdown > pre {
     margin: 0.5em 0;
     padding: 0.75em 0.75em;
     color: var(--code-theme-color);

src/components/InteractiveCode.astro

@@ -0,0 +1,193 @@
+---
+import { lex } from "../lexer/lexer";
+const {code, steps} = Astro.props;
+
+/** 
+ * Performs the following:
+ * - Removes the first & last line, if they are empty
+ * - Picks the indentation level from the first non-white line
+ * - Dedents the following lines
+*/
+function trimAndDedent(input: string): Array<string> {
+    let lines = input.split("\n");
+
+    // Remove empty lines at the start
+    while (lines[0] === "") {
+        lines = lines.slice(1);
+    }
+
+    // Get indentation level
+    let indentationLevel = 0;
+    for (const char of lines[0]!) {
+        if (char === " ") {
+            indentationLevel += 1;
+        } else {
+            break;
+        }
+    }
+
+    // Enforce indentation, or trim
+    for (let i = 0; i < lines.length; i += 1) {
+        // If the line is empty, continue
+        const characters = lines[i]!.split("");
+        if (characters.length === 0) {
+            continue;
+        }
+
+        // If all characters are whitespace, append just a newline
+        const nonWhitespace = characters.find((x) => x !== " ");
+        if (nonWhitespace === undefined) {
+            lines[i] = "";
+            continue;
+        }
+
+        // Enforce indentation
+        if (characters.length < indentationLevel) {
+            throw new Error("Invalid indentation while parsing THP code: " + lines[i]);
+        }
+        let currentIndentation = 0;
+        for (const c of characters) {
+            if (c === " ") { currentIndentation += 1 }
+            else {break;}
+        }
+        if (currentIndentation < indentationLevel) {
+            throw new Error("Invalid indentation while parsing THP code: " + lines[i]);
+        }
+
+        lines[i] = characters.slice(4).join("");
+    }
+
+
+    // Remove empty lines at the end
+    let endPosition = lines.length - 1;
+    while (true) {
+        if (lines[endPosition] === "") {
+            lines = lines.slice(0, -1);
+            endPosition -= 1;
+        } else {
+            break;
+        }
+    }
+
+    return lines;
+}
+
+function highlightCode(lines: Array<string>): string {
+    let outLines: Array<string> = [];
+
+    for (const [idx, line] of lines.entries()) {
+        const tokens = lex(line);
+        const lineArray = [
+            `<div class=\"inline-block w-full\" :class=\"line === ${idx + 1}? 'bg-green-200 dark:bg-green-900': ''\">`
+        ];
+
+        for (const token of tokens) {
+            if (token.token_type !== "") {
+                lineArray.push(`<span class="token ${token.token_type}">${token.v}</span>`);
+            } else {
+                lineArray.push(token.v);
+            }
+        }
+        lineArray.push("</div>");
+
+        outLines.push(lineArray.join(""));
+    }
+
+    return outLines.join("\n");
+}
+
+const codeHtml = highlightCode(trimAndDedent(code));
+---
+
+<div class="bg-black text-white rounded px-1"
+    x-data={`{
+        line: 0,
+        stdout: "",
+        ip: 0,
+        inst: ${steps},
+        done: false,
+        state: {},
+    }`}
+>
+    <span class="inline-block bg-[var(--code-theme-bg-acolor)] px-2 rounded-tl rounded-tr font-mono text-sm">thp code</span>
+    <pre class="language-thp" style="margin: 0;" data-disabled><code set:html={codeHtml}></code></pre>
+    <div class="grid grid-cols-2 font-mono text-sm">
+        <div>
+            <div class="p-1 border-b border-r border-white">stdout</div>
+            <div class="h-24 p-1 border-r border-white">
+                <pre><code class="bg-black" x-text="stdout"></code></pre>
+            </div>
+        </div>
+        <div>
+            <div class="p-1 border-b border-white">state</div>
+            <div class="h-24 p-1">
+                <template x-for="(value, key) in state">
+                    <div x-text="key + ' = ' + value"></div>
+                </template>
+            </div>
+        </div>
+    </div>
+    <div class="border-t border-white p-1">
+        <button class="font-mono px-1 rounded bg-pink-950 disabled:opacity-50 disabled:cursor-not-allowed" @click="alpineNext($data)" :disabled="done && 'true'">
+            Step: <span x-text="ip"></span>
+        </button>
+        <button class="font-mono px-1 rounded bg-pink-950" @click="alpineReset($data)">
+            Reset
+        </button>
+    </div>
+</div>
+
+<script>
+    type Instruction = "line" | "out" | "set";
+    type AlpineState = {
+        line: number,
+        stdout: string,
+        ip: number,
+        inst: Array<Array<[Instruction, string, string | undefined]>>
+        done: boolean,
+        state: {[key: string]: string},
+    }
+
+    /// Executes the instruction following the state of the machine.
+    function alpineNext(data: AlpineState) {
+        const len = data.inst.length;
+        const ip = data.ip;
+        data.ip += 1;
+
+        const instructions = data.inst[ip]!;
+        for (const instructionSet of instructions) {
+            const instructionArr = instructionSet;
+            switch (instructionArr[0]) {
+                case "line": {
+                    data.line = Number(instructionArr[1]);
+                    break;
+                }
+                case "out": {
+                    data.stdout += String(instructionArr[1])
+                    break;
+                }
+                case "set": {
+                    data.state[String(instructionArr[1])] = String(instructionArr[2]);
+                    break;
+                }
+            }
+        }
+
+        if (data.ip >= len) {
+            data.done = true;
+            return;
+        }
+    }
+    // @ts-ignore
+    window.alpineNext = alpineNext;
+    
+    function alpineReset(data: AlpineState) {
+        data.line = 0;
+        data.stdout = "";
+        data.ip = 0;
+        data.done = false;
+        data.state = {};
+    }
+    // @ts-ignore
+    window.alpineReset = alpineReset;
+</script>

src/layouts/BaseLayout.astro

@@ -35,5 +35,7 @@ const { title } = Astro.props;
 
     <body class="bg-c-bg text-c-text">
         <slot />
+
+        <script src="//unpkg.com/alpinejs" defer></script>
     </body>
 </html>

src/layouts/PagesLayout.astro

@@ -6,10 +6,10 @@ import Sidebar from "../components/Sidebar.astro";
 
 const { frontmatter, headings } = Astro.props;
 
-const posts = await Astro.glob("../pages/learn/**/*.md");
+const posts = await Astro.glob("../pages/learn/**/*.{md,mdx}");
 
 // The index.md page must have a `pagesLayout` frontmatter, which declares the order of all the pages.
-const indexSubpath = `/learn/index.md`;
+const indexSubpath = `/learn/index.mdx`;
 
 const indexPage = posts.find((post) => post.file.endsWith(indexSubpath));
 
@@ -35,7 +35,7 @@ function validateEntry(entry: PageEntry, basePath: string) {
     if (!entry.children) {
         // Attempt to get the page title from frontmatter
         const pageData = posts.find((post) =>
-            post.file.endsWith(entry.path + ".md"),
+            post.file.endsWith(entry.path + ".md") || post.file.endsWith(entry.path + ".mdx"),
         );
 
         if (pageData === undefined) {
@@ -116,6 +116,10 @@ for (const entry of pagesIndex) {
 
             for (const e of [...code_elements]) {
                 const el = e as HTMLElement;
+                // Some elements with .language-thp don't want to be processed
+                if (e.getAttribute("data-disabled") !== null)  {
+                    continue;
+                }
                 const pre_parent = el.parentElement!;
                 const new_div = document.createElement("div");
                 const code = el.innerText;

src/pages/learn/basics/hello-world.mdx

@@ -2,6 +2,7 @@
 layout: ../../../layouts/PagesLayout.astro
 title: Hello world
 ---
+import InteractiveCode from "../../../components/InteractiveCode.astro";
 
 # Hello, world!
 
@@ -12,3 +13,4 @@ print("Hello, world!")
 ```
 
 Then run `thp hello.thp`
+

src/pages/learn/error-handling/try.mdx

@@ -2,6 +2,7 @@
 layout: ../../../layouts/PagesLayout.astro
 title: Try/Exceptions
 ---
+import InteractiveCode from "../../../components/InteractiveCode.astro";
 
 # Try/exceptions
 
@@ -62,21 +63,62 @@ via try expressions:
 
 ### Naked try
 
-Use a naked `try` when you want to rethrow an error, if any.
+Use a naked `try` when you want to rethrow an error, if there is any.
 
-```thp
+<InteractiveCode 
-// May return an Int or an Exception
+    code={`
-fun dangerous() -> Int!Exception
+    fun dangerous() -> Int!Exception
-{...}
+    {   // May throw randomly
+        return if Math.random() < 0.5 { 50 }
+        else { Exception("Unlucky") }
+    }
+
+    fun run() -> !Exception
+    {   // If \`dangerous()\` throws, the function exits with the same error.
+        // Otherwise, continues
+        val result = try dangerous()
+        print("The result is {result}")
+    }
+
+    val res1 = run() // First, without error
+    val res2 = run() // Then, an example with error
+    `}
+    steps={`[
+        [["line", 14]],
+        [["line", 7]],
+        [["line", 10]],
+        [["line", 1]],
+        [["line", 3]],
+        [
+            ["line", 10],
+            ["set", "result", 50]
+        ],
+        [["line", 11]],
+        [
+            ["line", 14],
+            ["out", "The result is 50\\n"],
+        ],
+        [
+            ["line", 15],
+            ["set", "res1", "<empty>"],
+        ],
+        [["line", 7]],
+        [["line", 10]],
+        [["line", 1]],
+        [["line", 3]],
+        [["line", 4]],
+        [
+            ["line", 10],
+            ["set", "result", "Exception(\\"Unlucky\\")"]
+        ],
+        [["line", 15]],
+        [
+            ["line", 0,],
+            ["set", "res2", "Exception(\\"Unlucky\\")"],
+        ]
+    ]`}
+></InteractiveCode>
 
-fun run() -> !Exception
-{
-    // Use a naked `try` to rethrow if there's an error
-    val result = try dangerous()
-    // Here result is `Int`
-    print(result)
-}
-```
 
 In the previous example:
 

src/pages/learn/index.mdx

@@ -46,8 +46,9 @@ pagesLayout:
   - path: interfaces
   - path: anonymous
   - path: magic
-
 ---
+import InteractiveCode from "../../components/InteractiveCode.astro";
+
 
 # Welcome
 
@@ -57,12 +58,49 @@ THP is a new programming language that compiles to PHP.
 
 ![Accurate visual description of THP](/img/desc_thp.jpg)
 
-<br>
 
 This page discusses some of the design decitions of the language,
 if you want to install THP go to the [installation guide](install)
 
-If you want to learn the language, go to the learn section.
+
+## Interactive execution
+
+The documentation contains snippets of interactive THP code, like this:
+
+<InteractiveCode 
+    code={`
+    val x = "android"
+    var y = 17
+
+    fun f(Int a, Int b) {
+        print("hello, {a} {b}")
+    }
+
+    f(x, y)
+    `}
+    steps={`[
+        [["line", 1]],
+        [
+            ["line", 2],
+            ["set", "String x", "\\"android\\""]
+        ],
+        [
+            ["line", 8],
+            ["set", "Int y", "17"]
+        ],
+        [["line", 4]],
+        [["line", 5]],
+        [
+            ["out", "hello, android 17"],
+            ["line", 6]
+        ],
+        [["line", 8]],
+        [["line", 0]]
+    ]`}
+></InteractiveCode>
+
+Use the `Step` and `Reset` buttons to emulate the execution of a
+THP program!
 
 ## Goals
 

tailwind.config.mjs

@@ -19,7 +19,7 @@ export default {
             }
         },
         fontFamily: {
-            "mono": ["Iosevka", "'Iosevka Nerd Font'", "'Fira Code'", "monospace"],
+            "mono": ["'Iosevka Fixed Web'", "Iosevka", "'Iosevka Nerd Font'", "monospace"],
             "display": ["Inter", "'Josefin Sans'", "'Fugaz One'", "sans-serif"],
             "body": ["Inter", "sans-serif"],
         },