What & Why

A library to streamline (no pun intented) our code through an Unidirectional Data Flow based on Functional Reactive Programming (aka FRP) & OOP Observer and Iterator Design Pattern.

Introduce a new Asynchronous Structure concerning the code, but also the Error-Handling
=> The chief goal consist to make it easier the composition of asynchronous code

Declarative vs Imperative

Example between declarative and imperative mindset

Applying these functions declaratively meaning your code expresses the what and not the how of what you’re trying to accomplish

Functional Programming Principles & Mindset

1- First-Class Function: Function like Object (assignable inside in a variable) 2- Higher Order Function: function's parameter and return (that's why callback are available) 3- Immutable Data: Only primitive variable by defaut => We have to erase each variable 4- Recursion: call same function => tail recursion optimisation TODO: see Graf article consist to replace a stack empilement call par un simple appelle fonction Ainsi le compilateur est capable de le transformer en iteratif en réappelant et écrasant la même fonction juste modifiant les arguments Pour cela utiliser un accumulteur et retourner seulement la fonction ou l'accumulteur pour la condition de sortie. const fact = (n) => { if(n == 0) return 1 return n*fact(n-1) } /////////////////////////////////////////////////////////// const fact = (n) => { const factIntern = (n, acc) => { if(n > 0) return fact(n-1, n*acc) else return acc } return factIntern(n, 1) } const fib = (n) => { if(n <= 1) return 1 return fib(n-1) + fib(n-2) } /////////////////////////////////////////////////////////////////// const fib = (n, a = 1, b = 0) => { if(n === 0) return a return fib(n-1, a+b, a) } 5- Functor: Data type which can project a function inside each element in a specific context by flattening this context 6- Lazy Evaluation: compute code at last time need to be print => reason on infite set apply set theory thinking 7-Pure function: deterministic (same I => same O) => Function without random or other side-effect outside 8- Monad: Data type which can flatten before project a function inside each element in a specific context double flattening

Reactive Programming Principles & Mindset

Excel example to demonstrate reactive programming mindset


        stream1$ = [1];
        stream2$ = [2];
        streamAdd$ = stream1$.concat(stream2$).reduce(sum); // => 3
        stream1$.push(10);
        // What's going on? Concerning streamAdd$???

	Single Value	Multiple Value
Synchronous	Char - Boolean - Number	String - Array - Map
Asynchronous	Promise	Event Emitter - DOM Event

Callback


            getData(function(a){
                getMoreData(a, function(b){
                    getMoreMoreData(b, function(c){
                        getMoreMoreMoreData(c, function(d){
                            getMoreMoreMoreMoreData(d, function(e){
                                // and so on...
                            });
                        });
                    });
                });
            });

Horizontally nested calls => "Callback Hell"

Promises (FP principle)


            // Callback
            step1(value, function(data){
                step2(data, function(data2){
                    step3(data2, function(data3){
                    step4(data3, function(data4){
                        //INSTRUCTIONS ...
                    });
                    });
                });
            });

            // Promise
            step1.then(step2).then(step3).then(step4)

Promise returns an immutable, single postponed cached value

Promise drawbacks!

Manage only one value (not like mouse event or sequence of bytes in a file stream => no repeatable/retriable)
Once run/trig couldn't be cancelled

Don't worry stream is beautiful!

We have to shift our mindset to think in terms of streams, also known as functional sequences of events. RxJS implements under the hood through the use of familiar patterns such as Iterator and Observer.

	Single Value	Multiple Value
Synchronous	Observable	Observable
Asynchronous	Observable	Observable

What & Why

Paradigm Tree!

JavaScript Multi-Paradigm or Zero-Paradigm?

Appendix side-effect

Declarative vs Imperative

RxJS Principles & Mindset

Functional Programming Principles & Mindset

Reactive Programming Principles & Mindset

FP + RP = FRP!

Current common Type solution

"Once upon a time... Asynchronous"

Asynchronous emphasis

"Fin"

Callback

Promises (FP principle)

Promise drawbacks!

Don't worry stream is beautiful!

OOP DP

Observer

Iterator