Basics On Programming Paradigms

June 01, 2019

Procedural Program

• The ideas that programs are a sense of functions
• Goes from top to bottom
• Relies heavily on global state, but any line can change the global state
• C being a procedural language
• “Imperative” execution
• Easy to write, difficult to maintain
• Prone to difficult bugs

Object Oriented

• Based around a Primitive: object
• Objects have well defined interfaces
• Localised behaviour
• Objects control state
• Composition
• Code is still imperative - pro AND con! - Still telling the computer EXACTLY what to do.
• Can be more verbose

Declarative

• Describing what you want to happen, but not telling the computer how to do it
• Eg. SQL, Regex, HTML
• Data is self-describing
• As powerful as the interpreter allows
• As limiting as the interpreter allows - You want build a game in SQL etc.

Functional

• What we want to happen but not how
• Little state
• Few side effects
• Easy to reason about
• Composition
• Expressive
• Works great with OO
• Basis in higher math
• Cons to think differently
• Not always the best choice
• No loops, no control logic - Just telling it what we want to happen

Reactive

• Primitive: Observable
• Instead of describing data in terms of other data, we describe it in terms of streams of events - From this, we create a pipeline such that we certain data changes, a lot is processed and changed - Example: spreadsheets!
• Composition
• Expressive
• Data flows unidirectionally
• Tough to think differently
• Subscriptions help change the data

const cellC2$ = cellA2$.combineLatest(cellB2$).map(cells => cells[0] + cells[1])

cellC2$.subscribe(value => {
  console.log(value)
})

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