Complexity:
It's Not Complicated

Kyle Coberly

Which is more complex?

const array = [1, 2, 3]

let total = 0
for (let i = 0; i < array.length; i++){
      total += array[i] * 2
}

console.log(total)
const array = [1, 2, 3]

const doubleAndSum = (sum, number) => sum + number * 2
const total = array.reduce(doubleAndSum, 0)

console.log(total)

Accumulator - For Loop

Accumulator - Reduce

Which is more complex?

const array = [1, 2, 3]

let total = 0
for (let i = 0; i < array.length; i++){
      total += array[i] * 2
}

console.log(total)
Algorithmic Complexity O(n)
Cyclomatic Complexity 2
Skill-level Beginner
Statements 7
Non-Literal Expressions 3
Tokens 45
SLOCs 6

Accumulator - For Loop

Which is more complex?

Algorithmic Complexity O(n)
Cyclomatic Complexity 1
Skill-level Intermediate
Statements 4
Non-Literal Expressions 1
Tokens 41
SLOCs 4 
const array = [1, 2, 3]

const doubleAndSum = (sum, number) => sum + number * 2
const total = array.reduce(doubleAndSum, 0)

console.log(total)

Accumulator - Reduce

Which is more complex?

For Reduce
Algorithmic Complexity O(n) O(n)
Cyclomatic Complexity 2 1
Skill-level Beginner Intermediate
Statements 7 4
Non-Literal Expressions 3 1
Tokens 45 41
SLOCs 6 4

Which is more complex?

For Reduce
Algorithmic Complexity
Cyclomatic Complexity
Skill-level
Statements
Non-Literal Expressions 1
Tokens
SLOCs

DIFFICULTY

COMPLEXITY

SIMPLICITY

An Overview of Systems

Process

Interface

System

Systems are Processes

Simple Systems

Complicated Systems

Complex Systems

Feedback loops

[
    complicated,
    hard,
    chaotic
    verbose,
    confusing,
].includes(complex) === false

Complexity...

...it's not complicated?

Complex?

  • Tower of Hannoi
  • Rubik's Cube
  • Orbits
  • Software?

Simplicity

How many parts are there?

Simple

Complicated

Difficulty

How much effort is involved?

2 ²

Easy

Hard

√ 2

Stability

How predictable is the output?

1 + 1
Math.random()

Stable

Chaotic

Verbosity

What's the ratio of tokens to ideas?

!(x.map(x => x * 2))()
function doubleAll(numbers: number[]): number[]{
	const double = number => number * 2

	const doubledNumbers = numbers.map(double)
    
    return doubledNumbers
}

doubleAll(numbers)

Concise

Verbose

Clarity

How direct are the connections between parts?

Clear

Confusing

Complexity

Isolated

Complex

How interdependent are the parts?

Simple

Complicated

Easy

Hard

Stable

Chaotic

Concise

Verbose

Clear

Confusing

Isolated

Complex

Neat! So?

Complexity Kills
Limits Scale

(and then kills)

Algorithmic Complexity

users.forEach(user => {
  console.log("All users:")
  
  users.forEach(user => {
    console.log(user.name)
  })
})
User Count Logs Runtime at 1ms
100 10 thousand 10 seconds
10,000 100 million 28 hours
100 million 10 quadrillion 317,000 years

DEAD

Algorithmic Complexity

  • Non-negotiable
  • Eliminate the complexity through simplification

Program Complexity

if (productId === "a") {
  console.log("Apple")
} else if (productId === "b") {
  console.log("Banana")
} else if (productId === "c") {
  console.log("Carrot") 
}
const products = {
  a: "Apple",
  b: "Banana",
  c: "Carrot",
}

console.log(
  products[productId]
)
Conditional Polymorphic
Complexity O(n) O(1)
10,000 products... 10,000 ways to break 1 way to break
Change is... Increasingly risky Safe

DEAD

Program Complexity

  • Caused by:
    • Conditional logic
    • Shared mutable state
    • Indirect input and output
  • Try: Compartmentalization

Architectural Complexity

DEAD

Architectural Complexity

  • Caused by:
    • High coupling
    • Multiple sources of truth
    • Manual steps
  • Try: Simulation

Product Complexity

DEAD

Product Complexity

  • Non-negotiable
  • Caused by:
    • Poor product design
    • Poor architecture
    • Poor organization structure
    • Lack of feedback loops
  • Solve with:
    • Experimentation
    • Emergent design
    • Modular architecture
    • Break silos

Emergent Behaviors

Product

Architecture

Programs

Algorithms

Developer

Requirements

The Complexity Trap

The Complexity Trap

Plan

Analyze

Design

Build

Test

Maintain

Plan

Analyze

Design

Build

Test

Maintain

Process Complexity

Organizational Complexity

Plan

Analyze

Design

Build

Test

Maintain

PMs

BAs

Design

Dev

QA

TBD

Development != Math Worksheets

Static Design Dynamic Design
Design for efficient execution Design for efficient change
Coupled Modular
Prediction Experimentation
Silos Integrated teams

Development != Math Worksheets

"This is only a problem because they keep changing their mind"

Organization

Processes

Product

Architecture

Programs

Algorithms

$

Developer

Customer

Market

Market Complexity

$$

$

$$$

$$

$

(you are here)

Cynefin

Don't Treat Complex Like Complicated

Law of Requisite Complexity

Organization

Processes

Product

Because this needs to be easy to change...

... this needs to be easy to change

Implementation

... this needs to be easy to change

... this needs to be easy to change

...So where does the complexity go?

Automation

  • Development environments
  • Continuous Integration
  • Continuous Delivery
  • Testing
  • Infrastructure-as-Code
  • Chaos Monkeys

Your Complexity Toolbox ❤️

  • Simplification
  • Compartmentalization
  • Simulation
  • Emergent Design
  • Automation
  • Feedback Loops

Lol it was an agile talk

Solution Agile Practice
Simplification Refactoring
Compartmentalization Modular design
Simulation TDD
Emergent Design Iterative development
Automation CI/CD
Feedback Loops Retros, group programming

Kyle Coberly

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