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ReactiveArduino implements observable-observer pattern on a processor like Arduino. The purpose is to provide declarative programming approach, within the capacity constraints of a low-power MCU.

ReactiveArduino is heavily based onReactiveX andReactiveUI, adapted to the needs and limitations in a MCU.

The general use of ReactiveArduino consists of:

• Define an observable (Timer, Interval, FromArray, FromProperty...)
• Chain with one or more operators (Distinct, Where, Select, First, Last, Sum...)
• Subscribe an observer (Do, DoFinally, ToProperty, ToArray...)

For example:

FromRange(10,20).Select([](int x) {return x +10; }).Do( [](int x) { Serial.println(x); });

More examples in Wiki/Examples

More info about the Observables, Observers, and Operators available in theWiki

Observables are generally generated through factory methods provided by the Reactive class.For example:

FromArray<int>(values, valuesLength)

Chaining operators are usually make using 'Fluent Notation' which allows to combine observable and observers.For example:

observableInt.ToSerial();

To chain existing operators ReactiveArduino uses overload of operator>>.For example:

observableInt >> ToSerial<bool>();

ReactiveArduino has two types of observables, hot and cold.Hot observables emits the sequence when an observer subscribes to it. For example,FromArray(...) is a Hot Observable.

FromArray(values, valuesLength)

Cold observable does not emits any item when a observer subscribes to it. You have to explicitly call theNext() method whenever you want. For example,FromArrayDefer(...)

FromArrayDefer(values, valuesLength)

On many occasions we generate operators directly when we chain them, for example in theSetup(). However, creating an operator allocates dynamic memory. Therefore, you should avoid creating them inLoop(), or you could run out of memory.If you need to reuse (typically, call some operator method later in your code) set it as a global variable, and chain as normal.

auto counter = Count<int>();...//(later in code)...obsString >> counter >> ToSerial<String>();

This example show how to use Reactive Operator to perform a 3-elements Median filter, then a 4-elements Moving Average Filter, and make some action with the final filtered value.

#include"ReactiveArduinoLib.h"usingnamespaceReactive;int values[] = {0,1,4,6,2,5,7,3,5,8 };int valuesLength =sizeof(values) /sizeof(values[0]);voidsetup(){Serial.begin(9600);while (!Serial)delay(1);FromArray(values, valuesLength).Cast<float>().Median5().MovingAverage(4).DoAndFinally([](float x) { Serial.println(x); },[]() { Serial.println("No more items"); });}voidloop(){delay(2000);}

More examples in Wiki/Examples