code-explainer

Code Explainer

A skill that explains code snippets in clear, educational language. Helps developers understand unfamiliar code, algorithms, and programming patterns.

Skill Activation Triggers

Use this skill immediately when the user asks to:

• "Explain this code"
• "What does this function do?"
• "Break down this algorithm"
• "Help me understand this snippet"
• "Walk me through this code"
• "What's happening in this file?"

Key Indicators:

• User shares a code snippet and asks for explanation
• User is confused about existing code
• User wants to learn how something works
• User asks "what does X do?" about code

Do NOT use when:

• User wants to write new code
• User wants to fix a bug
• User wants code review with suggestions
• User wants refactoring recommendations

Quick Reference

Explanation Guidelines

Structure

A good code explanation should include:

1. Overview - One sentence summary of what the code does
2. Step-by-step breakdown - Walk through the logic
3. Key concepts - Explain any patterns or techniques used
4. Example - Show sample input/output if applicable

Tone

• Educational and approachable
• Avoid jargon unless explaining it
• Use analogies when helpful
• Assume the reader is smart but unfamiliar with this specific code

Language-Specific Tips

Examples

Example 1: Python Recursion

User prompt:

Explain this code:
```python
def factorial(n):
    if n <= 1:
        return 1
    return n * factorial(n - 1)

Good response:

This is a recursive function that calculates the factorial of a number.

Overview: It multiplies a number by all positive integers less than it (e.g., 5! = 5 × 4 × 3 × 2 × 1 = 120).

Step by step:

1. Base case (if n <= 1): If n is 0 or 1, return 1 (since 0! and 1! both equal 1)
2. Recursive case: Otherwise, multiply n by factorial(n-1)

Example: factorial(4) → 4 × factorial(3) → 4 × 3 × factorial(2) → 4 × 3 × 2 × factorial(1) → 4 × 3 × 2 × 1 = 24

Example 2: JavaScript Async/Await

User prompt:

What does this code do?
```javascript
async function fetchUserData(userId) {
  try {
    const response = await fetch(`/api/users/${userId}`);
    if (!response.ok) throw new Error('User not found');
    return await response.json();
  } catch (error) {
    console.error('Failed:', error);
    return null;
  }
}

Good response:

This is an async function that fetches user data from an API.

Overview: It makes an HTTP request to get a user's data, handles errors gracefully, and returns the result as JSON.

Step by step:

1. async function - Declares this function will use await for promises
2. await fetch(...) - Makes HTTP GET request, waits for response
3. if (!response.ok) - Checks if request succeeded (status 200-299)
4. await response.json() - Parses response body as JSON
5. catch block - If anything fails, logs error and returns null

Key pattern: This is the standard async/await pattern for API calls with error handling.

Error Cases

If the user provides:

• No code: Ask them to share the code they want explained
• Incomplete code: Explain what you can see and note what's missing
• Non-code text: Clarify you need actual code to explain

Integration Notes

This skill works well with:

• File reading tools (to access code from files)
• Language detection (to tailor explanations)
• Search tools (to find related documentation)