PureEvalTask
Task 可以安全的处理异步操作，可以被认为是异步版本的 Either 函子。
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
Task 的构造函数，用来进行 Task 的常规构造。
- Type
- Example
js
Task((reject, resolve) => {
//...do sth.
resolve(114514);
}); //Task actually 114514Task((reject, resolve) => {
//...do sth.
resolve(114514);
}); //Task actually 114514Task.map()
对 Task 中的值进行映射。
- 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()
在当前 Task 任务后拼接新的 Task 任务。
- 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()
将 Task 中的值映射取出，需要传入两个处理函数，第一个针对 reject 的情况，第二个针对 resolve 的情况。
- 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)
);