---

name: fp-react description: 在 React 中使用 fp-ts 的实用模式——hooks、状态、表单、数据获取。兼容 React 18/19、Next.js 14/15。 risk: unknown source: community version: 2.0.0 author: fp-ts-skills tags: [fp-ts, react, typescript, hooks, state-management, forms, data-fetching, remote-data, react-19, next-js]

React 中的函数式编程

React 应用的实用模式。没有术语，只有能用的代码。

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快速参考

| 模式 | 使用场景 | |---------|----------| | Option | 值可能不存在（用户尚未加载） | | Either | 操作可能失败（表单验证） | | TaskEither | 异步操作可能失败（API 调用） | | RemoteData | 需要显示加载/错误/成功状态 | | pipe | 链式多个转换 |

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1. 使用 Option 管理状态（可能存在，可能不存在）

使用 Option 代替 null | undefined 以获得更清晰的意图。

基本模式

import { useState } from 'react'
import * as O from 'fp-ts/Option'
import { pipe } from 'fp-ts/function'

interface User {
  id: string
  name: string
  email: string
}

function UserProfile() {
  // Option says "this might not exist yet"
  const [user, setUser] = useState<O.Option<User>>(O.none)

  const handleLogin = (userData: User) => {
    setUser(O.some(userData))
  }

  const handleLogout = () => {
    setUser(O.none)
  }

  return pipe(
    user,
    O.match(
      // When there's no user
      () => <button onClick={() => handleLogin({ id: '1', name: 'Alice', email: 'alice@example.com' })}>
        Log In
      </button>,
      // When there's a user
      (u) => (
        <div>
          <p>Welcome, {u.name}!</p>
          <button onClick={handleLogout}>Log Out</button>
        </div>
      )
    )
  )
}

链式可选值

import * as O from 'fp-ts/Option'
import { pipe } from 'fp-ts/function'

interface Profile {
  user: O.Option<{
    name: string
    settings: O.Option<{
      theme: string
    }>
  }>
}

function getTheme(profile: Profile): string {
  return pipe(
    profile.user,
    O.flatMap(u => u.settings),
    O.map(s => s.theme),
    O.getOrElse(() => 'light')
  )
}

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2. 使用 Either 进行表单验证

使用 Either 进行可能失败的操作——左侧是错误，右侧是成功。

import * as E from 'fp-ts/Either'
import { pipe } from 'fp-ts/function'

interface SignupForm {
  name: string
  email: string
  password: string
}

function validateForm(form: SignupForm): E.Either<string[], ValidatedForm> {
  return pipe(
    validateAll({
      name: pipe(validateName(form.name), E.mapLeft(e => [e])),
      email: pipe(validateEmail(form.email), E.mapLeft(e => [e])),
      password: pipe(validatePassword(form.password), E.mapLeft(e => [e])),
    })
  )
}

// Usage in component
function SignupForm() {
  const [form, setForm] = useState({ name: '', email: '', password: '' })
  const [errors, setErrors] = useState<string[]>([])

  const handleSubmit = () => {
    pipe(
      validateForm(form),
      E.match(
        (errs) => setErrors(errs),
        (valid) => {
          setErrors([])
          submitToServer(valid)
        }
      )
    )
  }

  return (
    <form onSubmit={e => { e.preventDefault(); handleSubmit() }}>
      <input
        value={form.name}
        onChange={e => setForm(f => ({ ...f, name: e.target.value }))}
        placeholder="Name"
      />
      <input
        value={form.email}
        onChange={e => setForm(f => ({ ...f, email: e.target.value }))}
        placeholder="Email"
      />
      <input
        type="password"
        value={form.password}
        onChange={e => setForm(f => ({ ...f, password: e.target.value }))}
        placeholder="Password"
      />
      {errors.length > 0 && (
        <ul style={{ color: 'red' }}>
          {errors.map((err, i) => <li key={i}>{err}</li>)}
        </ul>
      )}
      <button type="submit">Sign Up</button>
    </form>
  )
}