toResponse will convert a value into a Response body, set the content-type, and set the default response code for that type.

happstack-server Example:

 main = simpleHTTP nullConf $ toResponse "hello, world!"

will generate a Response with the content-type text/plain, the response code 200 OK, and the body: hello, world!.

simpleHTTP will call toResponse automatically, so the above can be shortened to:

 main = simpleHTTP nullConf $ "hello, world!"

happstack-lite Example:

 main = serve Nothing $ toResponse "hello, world!"

Minimal definition: toMessage (and usually toContentType).

alias for: fmap toResponse

turns m a into m Response using toResponse.

 main = simpleHTTP nullConf $ flatten $ do return "flatten me."

A low-level function to build a Response from a content-type and a ByteString.

Creates a Response in a manner similar to the ToMessage class, but without requiring an instance declaration.

example:

 import Data.ByteString.Char8 as C
 import Data.ByteString.Lazy.Char8 as L
 import Happstack.Server

 main = simpleHTTP nullConf $ ok $ toResponseBS (C.pack "text/plain") (L.pack "hello, world")

(note: pack and pack only work for ascii. For unicode strings you would need to use utf8-string, text, or something similar to create a valid ByteString).

Respond with 200 OK.

 main = simpleHTTP nullConf $ ok "Everything is OK"

Respond with 204 No Content

A 204 No Content response may not contain a message-body. If you try to supply one, it will be dutifully ignored.

 main = simpleHTTP nullConf $ noContent "This will be ignored."

Respond with 500 Internal Server Error.

 main = simpleHTTP nullConf $ internalServerError "Sorry, there was an internal server error."

Responds with 502 Bad Gateway.

 main = simpleHTTP nullConf $ badGateway "Bad Gateway."

Respond with 400 Bad Request.

 main = simpleHTTP nullConf $ badRequest "Bad Request."

Respond with 401 Unauthorized.

 main = simpleHTTP nullConf $ unauthorized "You are not authorized."

Respond with 403 Forbidden.

 main = simpleHTTP nullConf $ forbidden "Sorry, it is forbidden."

Respond with 404 Not Found.

 main = simpleHTTP nullConf $ notFound "What you are looking for has not been found."

A nicely formatted rendering of a Response

Respond with 413 Request Entity Too Large.

 main = simpleHTTP nullConf $ requestEntityTooLarge "That's too big for me to handle."

Respond with 303 See Other.

 main = simpleHTTP nullConf $ seeOther "http://example.org/" "What you are looking for is now at http://example.org/"

NOTE: The second argument of seeOther is the message body which will sent to the browser. According to the HTTP 1.1 spec,

the entity of the response SHOULD contain a short hypertext note with a hyperlink to the new URI(s).

This is because pre-HTTP/1.1 user agents do not support 303. However, in practice you can probably just use "" as the second argument.

Respond with 302 Found.

You probably want seeOther. This method is not in popular use anymore, and is generally treated like 303 by most user-agents anyway.

Respond with 301 Moved Permanently.

 main = simpleHTTP nullConf $ movedPermanently "http://example.org/" "What you are looking for is now at http://example.org/"

Respond with 307 Temporary Redirect.

 main = simpleHTTP nullConf $ tempRedirect "http://example.org/" "What you are looking for is temporarily at http://example.org/"

Set an arbitrary return code in your response.

A filter for setting the response code. Generally you will use a helper function like ok or seeOther.

 main = simpleHTTP nullConf $ do setResponseCode 200
                                 return "Everything is OK"

see also: resp

Same as setResponseCode status >> return val.

Use this if you want to set a response code that does not already have a helper function.

 main = simpleHTTP nullConf $ resp 200 "Everything is OK"

Honor an if-modified-since header in a Request. If the Request includes the if-modified-since header and the Response has not been modified, then return 304 (Not Modified), otherwise return the Response.