yamiteru / stoic

Tiny, fast and simple TypeScript functional reactive library.

Stoic

Tiny, fast and simple TypeScript functional reactive library.

Concepts

Observable

Something that emits values over time to which you can listen to. It starts its life once it's created and ends either by error or end.

There are 3 types of events to which you can listen to:

1. onNext listens to new values
2. onError listens to errors
3. onEnd listens to the end of the observable

There are 2 core types of observables:

1. stream doesn't remember the latest value
2. value does remember the latest value

Value mapping

Every observable has some sort of input and output value. Their shapes can be completely different and for that there is a map.

It accepts input value and outputs either output value or undefined. Undefined is used to stop the propagation of the output value to subscribers.

Derivation

Each observable type has its derived version. Derived observables derive their input value from an array of output values of other observables.

Derived observables are updated internally by an array of observables so there is no next method for manually passing input values into them.

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API

Observables

Stream

const simpleLogger$ = stream<[type: string, message: any]>(null, {
  next: ([type, message]) => console.log(type.toUpperCase(), message)
});

derivedStream

const squidStats$ = derivedStream([players$, reward$], ([players, reward]) => [
  `${players.length} 염`,
  `₩ ${reward.toWon()}`
]);

value

const price$ = value<number>(0, isPositive);
const count$ = value<number>(0, isPositive);

derivedValue

const sum$ = derivedValue([price$, count$], ([price, count]) => price * count);

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Future

• Tests
• Benchmarks
• pipe (once it's possible to define types that would support an unlimited number of functions)
• React hooks

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Have a beautiful day 🍀