# Problem Details for HTTP APIs (RFC7807) Extensible implementation of [RFC7807 — Problem Details for HTTP APIs ](https://tools.ietf.org/html/rfc7807) in Haskell. RFC7807 defines HTTP API error responses that are quite informative. Very basic example of such message could look like: ``` HTTP/1.1 404 Not Found Transfer-Encoding: chunked Date: Sun, 01 Nov 2020 22:28:42 GMT Server: Warp/3.3.13 Content-Type: application/problem+json;charset=utf-8 Content-Length: 251 { "type": "https://example.com/docs/error#upload-to-missing-file", "title": "File resource doesn't exist", "status": 404, "detail": "Cannot upload file content to a non-existent file.", "documentId": "ae095978-2f7c-47aa-84dd-220be55195a5" } ``` This library provides a data type `Rfc7807Error` that represents such error responses. It is designed to be extensible and to allow alternative representation of user defined fields.