λ JSON 转 Haskell 数据类型（Aeson）JSON to Haskell (Aeson)
根据 JSON 生成 Haskell 记录类型和 Aeson 的 FromJSON / ToJSON 实例：Text、Int、Double、[a]、Maybe a 等类型自动推断，字段名加类型前缀避免冲突。Generate Haskell record types with Aeson FromJSON / ToJSON instances from JSON: Text, Int, Double, [a] and Maybe a are inferred, and field names are prefixed with the type name to avoid clashes.
使用说明与常见问题How-to & FAQ
「JSON 转 Haskell 数据类型（Aeson）」是什么？What is the JSON to Haskell (Aeson) tool?
根据 JSON 生成 Haskell 记录类型和 Aeson 的 FromJSON / ToJSON 实例：Text、Int、Double、[a]、Maybe a 等类型自动推断，字段名加类型前缀避免冲突。Generate Haskell record types with Aeson FromJSON / ToJSON instances from JSON: Text, Int, Double, [a] and Maybe a are inferred, and field names are prefixed with the type name to avoid clashes.
如何使用「JSON 转 Haskell 数据类型（Aeson）」？How do I use the JSON to Haskell (Aeson)?
粘贴 JSON 并填写模块名（根类型名），下方生成完整的 Haskell 模块，需要依赖 aeson 和 text 包。用 decode 或 eitherDecode 解析 JSON。Paste JSON and set the module (root type) name to get a full Haskell module that depends on the aeson and text packages. Parse with decode or eitherDecode.
为什么字段名前面都带了类型名？Why are field names prefixed?
Haskell 的记录字段会生成同名的顶层函数，不同类型里有同名字段（如两个类型都有 id）会冲突。加上类型前缀（rootId、orderId）是最通用的解决办法，JSON 键名保持不变。Haskell record fields become top-level functions, so the same field name in two types (e.g. id) would clash. Prefixing with the type name (rootId, orderId) is the most portable fix; the JSON keys stay unchanged.
.: 和 .:? 有什么区别？.: vs .:?
.: 要求键必须存在，否则解析失败；.:? 在键不存在或值为 null 时返回 Nothing。工具会对样本中可能缺失或为 null 的字段使用 .:? 和 Maybe 类型。.: requires the key and fails otherwise; .:? returns Nothing when the key is missing or null. The tool uses .:? and Maybe for fields that may be missing or null in the sample.
「JSON 转 Haskell 数据类型（Aeson）」免费吗？数据会上传吗？Is the JSON to Haskell (Aeson) free? Is my data uploaded?
「JSON 转 Haskell 数据类型（Aeson）」完全免费，无需注册或安装，手机和电脑都能用；所有处理都在你的浏览器本地完成，输入的内容和文件不会上传到服务器。The JSON to Haskell (Aeson) is completely free with no sign-up or install and works on phones and desktops; everything runs locally in your browser and nothing you enter is uploaded.