Functional Programming with ES6

Guillaume Badi • 25.11.2015

Me ?

Developer Evangelist @Mailjet

Student @42

Node.JS fanboy

Autodidact

Twitter: @WeshGuillaume

This is the Government

(l’état, c’est moi)

Documents

Money

When the money comes from the “Companies”, we have a set of rules describing the way it has to be distributed.

The hierarchical approach makes it easy to visualize but hard to improve.

Problems

Nobody fully understands it

It requires tons of people to maintain

Adding new institutions is a pain

Changing something in one area requires changes in many other areas

Economists call it Bureaucracy

We call it Object Oriented programming

This is a structured mess

We want a function that takes the existing agents and returns new ones, when the money comes in.

Documents

Money

We could model it differently.

Companies1

Population1

Government1

Companies2

Population2

Government2

“It's not who I am underneath, but what I do that defines me.” - The Batman

Object Oriented Programming is good at describing things

Describing data.

Describing patterns

And by extension…

CAF = (salary, rent) => [Function]

Pole Emploi = (workPeriod) => [Function]

Institutions = (salary, rent, workPeriod) => [Function]

We want to “transform” our data, the mathematical way.

Functions should be pure. Understand “context-free”.

Functions are data that operate on some other data. It makes your code easy to test

Why is ES6 good for the Job ?

Function syntax is now short and clear

Returning functions is pure poetry

Same code in Go

Promises. comma.

Promises. period.

A lot of people just hate JavaScript

But precisely with this syntax, We have the choice to adopt a Java coding style...

Flatten a nested array

...Or a cleaner functional style

Functional programming is not simple. It requires

discipline and… meditation

Immutable data is one of the keys

Use map/filter/reduce when you can

If you have to use the words “and” or “then”, to describe your function, split it.

Documents

Money

We could model it differently.

Companies1

Population1

Government1

Companies2

Population2

Government2

Merci

Github: GuillaumebadiTwitter: @WeshGuillaume