Composing Software

Thank You

Composing Software: An Introduction

1. You Compose Software Every Day
2. Conclusion

The Dao of Immutability (The Way of the Functional Programmer)

1. Forward

The Rise and Fall and Rise of Functional Programming (Composable Software)

1. The Rise of Functional Programming
2. The Fall of Functional Programming
3. The Rise of Functional Programming
4. Functional Programming Has Always Been Alive and Well

Why Learn Functional Programming in JavaScript?

Pure Functions

1. What is a Function?
2. Mapping
3. Pure Functions
4. The Trouble with Shared State
5. Same Input, Same Output
6. No Side Effects
7. Conclusion

What is Functional Programming?

1. Pure Functions
2. Function Composition
3. Shared State
4. Immutability
5. Side Effects
6. Reusability Through Higher Order Functions
7. Containers, Functors, Lists, and Streams
8. Declarative vs Imperative
9. Conclusion

A Functional Programmer’s Introduction to JavaScript

1. Expressions and Values
2. Types
3. Destructuring
4. Comparisons and Ternaries
5. Functions
6. Currying
7. Function Composition
8. Arrays
9. Method Chaining
10. Conclusion

Higher Order Functions

Curry and Function Composition

1. What is a curried function?
2. What is a partial application?
3. What’s the Difference?
4. What is point-free style?
5. Why do we curry?
6. Trace
7. Curry and Function Composition, Together
8. Conclusion

Abstraction & Composition

1. Abstraction is simplification.
2. Abstraction in Software
3. Abstraction through composition
4. How to Do More with Less Code
5. Conclusion
6. Reduce
7. Reduce is Versatile
8. Conclusion

Abstract Data Types and the Software Crisis

1. Common ADT Examples
2. Why ADTs?
3. History of ADTs
4. Specifications for ADTs
5. Stack ADT Example
6. Concrete Implementations
7. Conclusion
8. Glossary

Functors & Categories

1. Why Functors?
2. Functor Laws
3. Category Theory
4. Build Your Own Functor
5. Curried Map
6. Conclusion

Monads

1. You’re probably already using monads.
2. What Monads are Made of
3. Building a Kleisli Composition Function
4. The Monad Laws
5. Conclusion

The Forgotten History of OOP

1. The Big Idea
2. The Essence of OOP
3. What OOP Doesn’t Mean
4. What is an object?
5. We’ve lost the plot.

Object Composition

1. What is Object Composition?
2. Three Different Forms of Object Composition
3. Notes on Code Examples
4. Aggregation
5. Concatenation
6. Delegation
7. Conclusion

Factory Functions

1. Literals for One, Factories for Many
2. Returning Objects
3. Destructuring
4. Computed Property Keys
5. Default Parameters
6. Type Inference
7. Factory Functions for Mixin Composition
8. Conclusion

Functional Mixins

1. Motivation
2. What are mixins?
3. What is functional inheritance?
4. What is a functional mixin?
5. Composing Functional Mixins
6. When to Use Functional Mixins
7. Caveats
8. Conclusion

Why Composition is Harder with Classes

1. The Delegate Prototype
2. The .constructor Property
3. Class to Factory is a Breaking Change

Composable Custom Data Types

1. You can do this with any data type
2. Composable Currency

Lenses

1. Why Lenses?
2. Background
3. Lens Laws
4. Composing Lenses

Transducers

1. Why Transducers?
2. Background and Etymology
3. A Musical Analogy for Transducers
4. Transducers compose top-to-bottom.
5. Transducer Rules
6. Transducing
7. The Transducer Protocol
8. Conclusion

Elements of JavaScript Style

1. 1. Make the function the unit of composition. One job for each function.
2. 2. Omit needless code.
3. 3. Use active voice.
4. 4. Avoid a succession of loose statements.
5. 5. Keep related code together.
6. 6. Put statements and expressions in positive form.
7. 7. Use parallel code for parallel concepts.
8. Conclusion: Code should be simple, not simplistic.

Mocking is a Code Smell

1. TDD should lead to better design.
2. What is a code smell?
3. What is a mock?
4. What is a unit test?
5. What is test coverage?
6. What is tight coupling?
7. What causes tight coupling?
8. What does composition have to do with mocking?
9. How do we remove coupling?
10. “Code smells” are warning signs, not laws. Mocks are not evil.