A protocol is a Typescript interface that describes a behaviour.
For example:
export interface Value<T> {
/**
* `valueOf()` returns the data stored in this value.
*/
valueOf(): T;
}We've adoped the term protocol from the Swift community. In particular, we call the code that implements a protocol an extension.
We think about protocols in the same way that the Golang standard library uses interfaces.
// we write functions that accept protocols, not class names
//
// you can pass anything in as the `location`,
// as long as it implements the `Retrieval` protocol
function retrieve(logger: Logger, location: Retrieval) {
logger.logInfo("retrieving data");
return location.retrieve();
}