PureEvalTask
Task can safely handle asynchronous operations and can be considered as the asynchronous version of the Either functor.
js
import { readFile } from 'fs';
function myReadFile(fileName) {
return Task((reject, resolve) => {
readFile(fileName, (err, data) => {
if (err) reject(err);
else resolve(data.toString());
});
});
}
myReadFile('test.js').map(trim).map(toUpper).fold(console.error, console.log);import { readFile } from 'fs';
function myReadFile(fileName) {
return Task((reject, resolve) => {
readFile(fileName, (err, data) => {
if (err) reject(err);
else resolve(data.toString());
});
});
}
myReadFile('test.js').map(trim).map(toUpper).fold(console.error, console.log);Task
The constructor function for Task, used for regular Task construction.
- Type
- Example
js
Task((reject, resolve) => {
//...do sth.
resolve(114514);
}); //Task actually 114514Task((reject, resolve) => {
//...do sth.
resolve(114514);
}); //Task actually 114514Task.map()
Maps over the value inside the Task.
- Type
- Example
js
Task((reject, resolve) => {
//...do sth.
resolve(114513);
}).map(add(1)); //Task actually 114514Task((reject, resolve) => {
//...do sth.
resolve(114513);
}).map(add(1)); //Task actually 114514Task.chain()
Chains a new Task operation after the current Task.
- Type
- Example
js
const fetchData = (url) =>
Task((reject, resolve) => {
//fetch...
});
const processData = (data) =>
Task((reject, resolve) => {
//process..
});
const combinedTask = fetchData('https://example.com/data').chain(processData);
combinedTask.fold(
(error) => console.error(error),
(result) => console.log(result)
);const fetchData = (url) =>
Task((reject, resolve) => {
//fetch...
});
const processData = (data) =>
Task((reject, resolve) => {
//process..
});
const combinedTask = fetchData('https://example.com/data').chain(processData);
combinedTask.fold(
(error) => console.error(error),
(result) => console.log(result)
);Task.fold()
Extracts the value from the Task by applying two handling functions; the first one for the reject case and the second one for the resolve case.
- Type
- Example
js
const fetchData = (url) =>
Task((reject, resolve) => {
//fetch...
});
const processData = (data) =>
Task((reject, resolve) => {
//process..
});
const combinedTask = fetchData('https://example.com/data').chain(processData);
combinedTask.fold(
(error) => console.error(error),
(result) => console.log(result)
);const fetchData = (url) =>
Task((reject, resolve) => {
//fetch...
});
const processData = (data) =>
Task((reject, resolve) => {
//process..
});
const combinedTask = fetchData('https://example.com/data').chain(processData);
combinedTask.fold(
(error) => console.error(error),
(result) => console.log(result)
);