Use Promise, Future and some functional programing stuff without being a math nerd.

Use Promises, Futures and some functional programing stuff without being a math nerd.

@waxzce Quentin ADAM at

Quentin ADAM from the Clever Cloud@waxzce on twitter github- soundcloud instagram .Who am I ?

My day to day work : Clever Cloud, make your app run all the time

And learn a lot of things about your code, apps, and good/bad designKeep your apps online. made with node.js, scala, java, ruby, php, python, go

And learn a lot of things about your code, apps, and good/bad design

Im not a math nerd

Node.js main problem

So, try to keep it alive and minimize error exposure

On the other hand: the callback soup

example : database connection

Really ? All DB interaction in one callback ?

Really ? Uncatched exceptions bubble to the top and kill the app ?

Really ? If/else/undefined error treatment ?

DB driver shouldnt drive your code architecture, theorically

So, we have a problem : how to use a value we dont have yet, and use it in the future?

Change your mindhow do you interact with data now?

example

You want to return something !

you mix I/O handling with your business processesThe other problem :

Split

Change your mindhow can we do it?

Work on future data you have promised to your code ;-)

Examplesimple promise map

Examplesimple promise map

More important : you can return a data you dont have At The Moment

No more dealing with blocking I/o in your business code

Dealing with multiple future data

And stop using boolean counter for event ready.Get all you need to work

Real world example

Built in error management

Simple way : you can return someting :-)

Promises will manage temporality problems and I/O in a simple way

Not too complicated ?

Weve just dealt with Functors, monads, semigroups all of these algebraic structures

Math words, not so complicated, just made to share concepts between people :-)

Functional programing is not a language : its the ability to use algebraic structures and math tools in your codeSo you can reuse it where you want

Made by the awesome Brian McKenna - @puffnfreshFunctional Javascript : fantasy land specification and code

https://github.com/petkaantonov/bluebirdBluebird

Try it you will

But there is more

Data structures can drive your code to avoid runtime problems

Null pointer exception

Put lot of if/else in your code ?

Optional type Maybe you can use

Safe storage box

Algebra data modelOption

Example

Example

Act optional the time you need, then decide

Code is more clean & you avoid NPE

Made by the awesome Brian McKenna - @puffnfreshFunctional Javascript : fantasy land specification and code

French article : http://www.touilleur-express.fr/2014/11/07/optional-en-java-8/ Java 8 optional type !

To understand Functional pattern value Or try SCALA

Functional goal :Avoid runtime errorsCode clarityBe predicable

Loops ?

Classic iteration

Classic iteration

Classic iteration

Much more readable !

Using underscore.js and lodash.js

Modern javascript implementation

Functional : Apply function on data

simple

You can use it everywhere

Be a badass !

I give you a www.clever-cloud.com gift : devoxxMA15

Im on twitter : @waxzceThank you !Any questions ?