By-Example Tutorial Creation Skill

Purpose

This Skill provides comprehensive guidance for creating by-example tutorials - a code-first learning path designed for experienced developers who want rapid language pickup through heavily annotated working code examples.

When to use this Skill:

• Creating by-example tutorials for programming languages
• Writing heavily annotated code examples for education
• Designing code-first learning paths
• Achieving 95% language coverage through examples
• Meeting annotation density standards (1-2.25 comments per code line)
• Targeting experienced developers who know at least one language well

Core Concepts

What is By-Example?

By-example tutorials are a code-first learning path that achieves 95% language coverage through 75-90 heavily annotated, self-contained code examples.

NOT a replacement for:

• Beginner tutorials (which provide deep explanations for complete beginners)
• Quick Start (which is 5-30% coverage touchpoints)
• Cookbook (which is problem-solving oriented, not learning-oriented)

Target Audience:

• Experienced developers: Seasonal programmers, software engineers
• Already know at least one programming language well
• Want quick language pickup without extensive narrative
• Prefer learning through working code
• Need 90% coverage efficiently

Five-Part Example Structure

Each example follows a consistent five-part structure:

### Example N: Concept Name

**Brief explanation** (1-3 sentences describing what this example demonstrates)

**Optional diagram** (Mermaid diagram if concept relationships complex)

**Heavily commented code** (self-contained, runnable example with educational annotations)

**Key takeaway** (1-2 sentences summarizing the lesson)

Annotation Density Standards

The 1-2.25 Rule

CRITICAL: Target 1.0-2.25 comment lines per code line PER EXAMPLE

Measurement: Each code block is measured independently

• Minimum: 1.0 (examples below this need enhancement)
• Optimal: 1-2.25 (target range for educational value)
• Upper bound: 2.5 (examples exceeding this need reduction)

Annotation Pattern

Use // => or # => notation to document:

• Values: Show variable values after assignment
• States: Show object/data structure states after modification
• Outputs: Show console/print output
• Side effects: Show file changes, network calls, database updates
• Intermediate steps: Show values during complex operations

Examples:

// Simple line (1 annotation)
int x = 10;                      // => x is 10 (type: int)

// Complex line (2 annotations)
String result = transform(x);    // => Calls transform with 10
                                 // => result is "10-transformed" (type: String)

// Output line (1 annotation)
System.out.println(result);      // => Output: 10-transformed

# Simple operation (1 annotation)
numbers = [1, 2, 3, 4, 5]       # => numbers is [1, 2, 3, 4, 5] (type: list)

# Complex operation (2 annotations)
squared = [n**2 for n in numbers]  # => List comprehension squares each number
                                    # => squared is [1, 4, 9, 16, 25]

# Output (1 annotation)
print(squared)                  # => Output: [1, 4, 9, 16, 25]

Quality Over Quantity

Focus on:

• Concise explanations that scale with code complexity
• Simple operations get brief annotations
• Complex operations get detailed breakdowns
• Avoid repetitive patterns across similar code

Self-Containment Rules

What is Self-Contained?

Each example MUST be:

• Runnable without dependencies: No external libraries, files, or setup
• Complete: All necessary code in the example
• Independent: Doesn't require previous examples to work
• Verified: Actually runs and produces shown output

How to Achieve Self-Containment

DO:

• Use only standard library features
• Include all helper functions/classes in example
• Provide sample data inline
• Show complete working code

DON'T:

• Require external packages (unless demonstrating that package)
• Reference code from previous examples
• Assume reader has specific files/data
• Show partial code snippets that won't compile

Example (Java):

// Self-contained - includes helper class
class Person {
    private String name;
    private int age;

    public Person(String name, int age) {  // => Constructor
        this.name = name;                  // => Sets name field
        this.age = age;                    // => Sets age field
    }

    public String getName() { return name; }  // => Getter for name
}

public class Example {
    public static void main(String[] args) {
        Person p = new Person("Alice", 30);  // => Creates Person object
                                               // => p.name is "Alice", p.age is 30
        System.out.println(p.getName());     // => Output: Alice
    }
}

Multiple Code Blocks for Comparisons

CRITICAL: Use multiple code blocks with text between when showing comparisons, alternatives, or before/after patterns.

DO NOT combine different approaches in single code block. Separate them for clarity.

Example Pattern:

### Example: Mutable vs Immutable Approach

**Comparison**: Java String (immutable) vs StringBuilder (mutable)

**Immutable approach (String)**:

```java
String str = "Hello";           // => str is "Hello"
str = str + " World";           // => Creates NEW string
                                 // => str is "Hello World" (original discarded)
System.out.println(str);        // => Output: Hello World
```

**Text explanation**: Strings are immutable. Each concatenation creates a new String object, making repeated concatenations inefficient.

**Mutable approach (StringBuilder)**:

```java
StringBuilder sb = new StringBuilder("Hello");  // => sb is "Hello"
sb.append(" World");                             // => Modifies EXISTING object
                                                 // => sb is "Hello World" (no new object)
System.out.println(sb.toString());               // => Output: Hello World
```

**Text explanation**: StringBuilder is mutable. Append operations modify the existing object, making repeated concatenations efficient.

**Key takeaway**: Use String for immutable, final values. Use StringBuilder for building strings incrementally.

Coverage Progression

Three Tutorial Levels

By-example tutorials are split into three difficulty levels:

Beginner (Examples 1-15):

• Coverage: 0-40% of language features
• Focus: Basic syntax, control flow, functions, simple data structures
• Annotation density: 1.5-2.25 (higher for fundamentals)

Intermediate (Examples 16-35):

• Coverage: 40-75% of language features
• Focus: OOP/functional programming, modules, error handling, common patterns
• Annotation density: 1.0-1.75 (moderate for standard features)

Advanced (Examples 36-60+):

• Coverage: 75-95% of language features
• Focus: Concurrency, metaprogramming, internals, advanced patterns
• Annotation density: 1.0-1.5 (concise for experienced developers)

Total Coverage Target

Goal: 75-90 examples achieving 95% language coverage

Not covered (remaining 5%):

• Extremely rare features
• Deprecated features
• Platform-specific edge cases
• Niche use cases

Mermaid Diagram Usage

When to Use Diagrams

Use diagrams for:

• Complex concept relationships
• Data flow in multi-step operations
• Object hierarchies
• State transitions
• Execution flow in async/concurrent code

Skip diagrams for:

• Simple syntax examples
• Single-operation code
• Linear execution flow
• When code is self-explanatory

Accessible Color Requirements

CRITICAL: All Mermaid diagrams MUST use accessible color palette

Use the docs__creating-accessible-diagrams Skill for complete color guidance.

Verified Accessible Palette:

• Blue: #0173B2
• Orange: #DE8F05
• Teal: #029E73
• Purple: #CC78BC
• Brown: #CA9161

Common Patterns

Pattern 1: Basic Syntax Example

### Example 1: Variable Declaration and Type Inference

**Demonstrates**: Basic variable declaration with type inference

```java
var x = 10;                    // => x is 10 (type: int, inferred)
var name = "Alice";            // => name is "Alice" (type: String, inferred)
var pi = 3.14;                 // => pi is 3.14 (type: double, inferred)

System.out.println(x);         // => Output: 10
System.out.println(name);      // => Output: Alice
System.out.println(pi);        // => Output: 3.14
```

Key takeaway: Use var for local variables when type is obvious from initializer.

### Pattern 2: Complex Operation with Diagram

````markdown
### Example 25: Stream Pipeline Transformation

**Demonstrates**: Multi-stage data transformation using streams

**Data flow diagram**:

```mermaid
graph LR
    A[Source List] -->|filter| B[Even Numbers]
    B -->|map| C[Squared Values]
    C -->|collect| D[Result List]

    style A fill:#0173B2,stroke:#000,color:#fff
    style B fill:#DE8F05,stroke:#000,color:#000
    style C fill:#029E73,stroke:#000,color:#fff
    style D fill:#CC78BC,stroke:#000,color:#000

List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6);  // => Source data

List<Integer> result = numbers.stream()              // => Creates stream
    .filter(n -> n % 2 == 0)                         // => Keeps only even: [2, 4, 6]
    .map(n -> n * n)                                 // => Squares each: [4, 16, 36]
    .collect(Collectors.toList());                   // => Collects to List

System.out.println(result);                          // => Output: [4, 16, 36]

Key takeaway: Stream pipelines enable declarative data transformations with filter, map, and collect operations.

### Pattern 3: Comparison Example (Multiple Code Blocks)

````markdown
### Example 40: Exception Handling - Try-Catch vs Try-With-Resources

**Comparison**: Manual resource closing vs automatic resource management

**Manual approach (try-catch-finally)**:

```java
BufferedReader reader = null;
try {
    reader = new BufferedReader(new FileReader("data.txt"));  // => Opens file
    String line = reader.readLine();                           // => Reads first line
    System.out.println(line);                                  // => Output: [file content]
} catch (IOException e) {
    e.printStackTrace();                                       // => Handles errors
} finally {
    if (reader != null) {
        try {
            reader.close();                                    // => Closes manually
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
```

**Problem**: Verbose, error-prone (might forget to close), nested try-catch in finally.

**Automatic approach (try-with-resources)**:

```java
try (BufferedReader reader = new BufferedReader(new FileReader("data.txt"))) {
    // => Opens file, reader auto-closes when block exits
    String line = reader.readLine();                  // => Reads first line
    System.out.println(line);                         // => Output: [file content]
    // => reader.close() called automatically here
} catch (IOException e) {
    e.printStackTrace();                              // => Handles errors
}
```

**Benefit**: Concise, safe (guaranteed closing), no nested try-catch.

**Key takeaway**: Use try-with-resources for automatic resource management. Implements AutoCloseable interface.

Best Practices

Example Creation Workflow

1. Identify concept: What specific feature/pattern to demonstrate?
2. Write working code: Ensure it compiles and runs
3. Make self-contained: Remove external dependencies
4. Add annotations: 1-2.25 comments per code line
5. Verify output: Run code, document actual output
6. Add diagram (if complex): Use accessible colors
7. Write takeaway: 1-2 sentence lesson summary
8. Measure density: Count annotations per code line

Annotation Guidelines

DO:

• Document WHAT happens at each step
• Show variable values after operations
• Indicate types when useful
• Explain side effects
• Use consistent // => or # => notation

DON'T:

• Repeat obvious information ("assigns 10 to x" when code shows x = 10)
• Write paragraphs (keep annotations concise)
• Skip intermediate values in complex operations
• Use inconsistent notation styles

Quality Checklist

Before publishing by-example tutorial:

• 75-90 examples total
• 95% language coverage achieved
• Each example follows five-part structure
• Annotation density 1.0-2.25 per example
• All examples are self-contained and runnable
• Multiple code blocks used for comparisons
• Diagrams use accessible color palette
• Examples progress from beginner → intermediate → advanced
• Key takeaways summarize lessons clearly

Common Mistakes

❌ Mistake 1: File-level annotation density instead of per-example

Wrong: Measuring annotations across entire file

Right: Measure each example independently. One example with 0.5 density and another with 2.0 density both fail (first too low, second acceptable). Target 1.0-2.25 for EACH example.

❌ Mistake 2: Combining different approaches in single code block

// WRONG! Mixed mutable and immutable in one block
String str = "Hello";
str = str + " World";
StringBuilder sb = new StringBuilder("Hello");
sb.append(" World");

Right: Use multiple code blocks with text between explaining differences.

❌ Mistake 3: Examples requiring external setup

// WRONG! Requires database setup
Connection conn = DriverManager.getConnection("jdbc:...");
// Users can't run this without database

Right: Use in-memory data structures or mock objects for self-containment.

❌ Mistake 4: Missing intermediate values

// WRONG! Complex operation with no intermediate annotations
int result = numbers.stream()
    .filter(n -> n % 2 == 0)
    .map(n -> n * n)
    .reduce(0, Integer::sum);  // => result is 56

Right: Annotate each stage showing intermediate values.

❌ Mistake 5: Paragraph annotations

// WRONG! Too verbose
int x = 10;  // This line declares a variable named x and assigns it the integer value 10. Variables in Java must have a type, and here the type is int which represents 32-bit signed integers ranging from -2,147,483,648 to 2,147,483,647.

Right: Concise annotations scaling with code complexity.

References

Primary Convention: By Example Tutorial Convention

Related Conventions:

• Programming Language Tutorial Structure - Dual-path organization
• Programming Language Content Standard - Universal content architecture
• Hugo ayokoding Convention - Code annotation standards for ayokoding-web

Related Skills:

• apps__ayokoding-web__developing-content - ayokoding-web specific patterns for hosting tutorials
• docs__creating-accessible-diagrams - Accessible diagram creation for complex examples

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This Skill packages critical by-example tutorial creation knowledge for rapid language pickup. For comprehensive details, consult the primary convention document.