Introduction: Empirical Language Proof

Why This Book Exists

This is not a typical language tutorial. This is an empirical proof that Ruchy works.

Every feature documented here has:

  • ✅ Runnable code you can copy into the notebook
  • ✅ Expected output you can verify
  • ✅ Automated tests proving it works
  • ✅ Coverage reports proving tests are thorough
  • ✅ Mutation tests proving tests catch real bugs
  • ✅ E2E tests proving it works in browsers

The Promise

If you can run this code in the Ruchy notebook and get the expected output, the language feature works.

No hand-waving. No "coming soon." No "should work."

Just: Here's the code, here's the output, here's the test that proves it.

How to Use This Book

1. Run the Notebook

# Start the notebook server
cargo run --features notebook --bin ruchy notebook

# Or open the web version
open http://localhost:8000/notebook.html

2. Try Each Feature

Copy the code from each chapter into the notebook. Run it. Verify the output matches.

3. Check the Proof

Every chapter links to:

  • The automated test file
  • The coverage report
  • The mutation test results
  • The E2E test

If you don't trust the docs, check the tests.

Quality Standards

This book and the notebook are held to wasm-labs EXTREME quality standards:

Coverage Requirements

  • ✅ Line Coverage: ≥85%
  • ✅ Branch Coverage: ≥90%
  • ✅ Mutation Score: ≥90%

Testing Requirements

  • ✅ Unit Tests: Every function
  • ✅ Property Tests: 10,000+ random inputs
  • ✅ Mutation Tests: Empirical bug-catching proof
  • ✅ E2E Tests: Real browsers (Chrome, Firefox, Safari)

WASM Requirements

  • ✅ Size: <500KB
  • ✅ Purity: 0 WASI imports
  • ✅ Validation: Deep bytecode inspection

The 41 Features

This book proves all 41 Ruchy language features work in the notebook:

Foundation (9 features)

  1. Integer/Float/String/Bool/Nil literals
  2. Variable binding and assignment
  3. Comments (line and block)
  4. Arithmetic operators (+, -, *, /, %)
  5. Comparison operators (<, >, <=, >=, ==, !=)
  6. Logical operators (&&, ||, !)
  7. Bitwise operators (&, |, ^, <<, >>)
  8. If-else expressions
  9. Match expressions

Functions & Data (11 features)

  1. For loops
  2. While loops
  3. Loop control (break, continue)
  4. Function definitions
  5. Function parameters and returns
  6. Closures and lambdas
  7. Higher-order functions
  8. Arrays
  9. Tuples
  10. Objects/Maps
  11. Structs

Advanced (10 features)

  1. Enums
  2. Pattern destructuring
  3. Pattern guards
  4. Exhaustiveness checking
  5. Try-catch error handling
  6. Option type
  7. Result type
  8. String interpolation (f-strings)
  9. String methods
  10. String escaping

Standard Library (10 features)

  1. File I/O (fs)
  2. HTTP client
  3. JSON parsing
  4. Path operations
  5. Environment variables
  6. Process execution
  7. Time/Date operations
  8. Logging
  9. Regular expressions
  10. DataFrames

Meta (1 feature)

  1. WASM compilation

Let's Begin

Ready to see the proof? Let's start with the basics: literals.

Continue to Basic Syntax →