Programming Design Patterns

Design Considerations

• Maintainability
• Ease of Development
• Functionality

Design Patterns

• Object Oriented Programming
• Functional Programming

You can have it all! 

Object Oriented Programming

Characteristics

• Persistent State
• Side Effects

Techniques

• Inheritance
• Encapsulation
• Polymorphism

Consequences

• Familiarity
• Ease of Development
• Scope Control

Functional Programming

Characteristics

• First Class Objects
• Referential Transparency (Purity)
• Function Composition
• Immutability
• Declarative

//PURE FUNCTION !!!!!!!!!
const addTwoNumbers = function(a,b){
  return a + b
}

addTwoNumbers(1,3) //This will ALWAYS be 4

//IMPURE FUNCTIONS !!!!!!!!!
let userName = 'Functor The Funky '

const AddToUserName = function(stringToAdd){
  return userName += stringToAdd
}

const removeFromUserName = function(stringToAdd){
  return userName -= stringToAdd
}

mutateUserName(userName,'Function') //'Functor The Funky Function'

Techniques

• Higher Order Functions
• Currying
• Partial Execution & Closures
• Recursion 
  • Loops mutate state!
• Memoization

Consequences

• Seperation of Concerns
• Reduction in lines of code
• Ease of parallelization
• Formal proofs of programs!

Anti-Patterns

Go forth and prosper