Safe Haskell	None
Language	Haskell2010

Web.Twain

Contents

Routing
Requests
Responses
Errors
Middleware
Parameters
Re-exports

Description

Twain is a tiny web application framework for WAI

ResponderM for composing responses with do notation.
Routing with path captures that decompose ResponderM into middleware.
Parameter parsing for cookies, path, query, and body.
Helpers for redirects, headers, status codes, and errors.

{--}

import Network.Wai.Handler.Warp (run)
import Web.Twain

main :: IO ()
main = do
  run 8080 $
    foldr ($)
      (notFound missing)
      [ get "/" index
      , post "echo:name" echo
      ]

index :: ResponderM a
index = send $ html "Hello World!"

echo :: ResponderM a
echo = do
  name <- param "name"
  send $ html $ "Hello, " <> name

missing :: ResponderM a
missing = send $ html "Not found..."

Synopsis

data ResponderM a
get :: PathPattern -> ResponderM a -> Middleware
put :: PathPattern -> ResponderM a -> Middleware
patch :: PathPattern -> ResponderM a -> Middleware
post :: PathPattern -> ResponderM a -> Middleware
delete :: PathPattern -> ResponderM a -> Middleware
route :: Maybe Method -> PathPattern -> ResponderM a -> Middleware
notFound :: ResponderM a -> Application
param :: ParsableParam a => Text -> ResponderM a
paramEither :: ParsableParam a => Text -> ResponderM (Either HttpError a)
paramMaybe :: ParsableParam a => Text -> ResponderM (Maybe a)
params :: ResponderM [Param]
file :: Text -> ResponderM (FileInfo ByteString)
fileMaybe :: Text -> ResponderM (Maybe (FileInfo ByteString))
files :: ResponderM [File ByteString]
fromBody :: FromJSON a => ResponderM a
header :: Text -> ResponderM (Maybe Text)
headers :: ResponderM [Header]
request :: ResponderM Request
send :: Response -> ResponderM a
next :: ResponderM a
redirect301 :: Text -> Response
redirect302 :: Text -> Response
redirect303 :: Text -> Response
text :: Text -> Response
html :: ByteString -> Response
json :: ToJSON a => a -> Response
xml :: ByteString -> Response
css :: ByteString -> Response
raw :: Status -> [Header] -> ByteString -> Response
status :: Status -> Response -> Response
withHeader :: Header -> Response -> Response
withCookie :: Text -> Text -> Response -> Response
withCookie' :: SetCookie -> Response -> Response
expireCookie :: Text -> Response -> Response
data HttpError = HttpError Status String
onException :: (SomeException -> ResponderM a) -> Middleware
withParseBodyOpts :: ParseRequestBodyOptions -> Middleware
withMaxBodySize :: Word64 -> Middleware
class ParsableParam a where
- parseParam :: Text -> Either HttpError a
- parseParamList :: Text -> Either HttpError [a]
module Network.HTTP.Types
module Network.Wai
data FileInfo c = FileInfo {
- fileName :: ByteString
- fileContentType :: ByteString
- fileContent :: c
}

Documentation

data ResponderM a Source #

ResponderM is an Either-like monad that can "short-circuit" and return a response, or pass control to the next middleware. This provides convenient branching with do notation for redirects, error responses, etc.

Instances

Instances details

Monad ResponderM Source #
Instance details Defined in Web.Twain.Types Methods (>>=) :: ResponderM a -> (a -> ResponderM b) -> ResponderM b # (>>) :: ResponderM a -> ResponderM b -> ResponderM b # return :: a -> ResponderM a #
Functor ResponderM Source #
Instance details Defined in Web.Twain.Types Methods fmap :: (a -> b) -> ResponderM a -> ResponderM b # (<$) :: a -> ResponderM b -> ResponderM a #
Applicative ResponderM Source #
Instance details Defined in Web.Twain.Types Methods pure :: a -> ResponderM a # (<>) :: ResponderM (a -> b) -> ResponderM a -> ResponderM b # liftA2 :: (a -> b -> c) -> ResponderM a -> ResponderM b -> ResponderM c # (>) :: ResponderM a -> ResponderM b -> ResponderM b # (<*) :: ResponderM a -> ResponderM b -> ResponderM a #
MonadIO ResponderM Source #
Instance details Defined in Web.Twain.Types Methods liftIO :: IO a -> ResponderM a #
MonadThrow ResponderM Source #
Instance details Defined in Web.Twain.Types Methods throwM :: Exception e => e -> ResponderM a #
MonadCatch ResponderM Source #
Instance details Defined in Web.Twain.Types Methods catch :: Exception e => ResponderM a -> (e -> ResponderM a) -> ResponderM a #

Routing

get :: PathPattern -> ResponderM a -> Middleware Source #

put :: PathPattern -> ResponderM a -> Middleware Source #

patch :: PathPattern -> ResponderM a -> Middleware Source #

post :: PathPattern -> ResponderM a -> Middleware Source #

delete :: PathPattern -> ResponderM a -> Middleware Source #

route :: Maybe Method -> PathPattern -> ResponderM a -> Middleware Source #

Route request matching optional Method and PathPattern to ResponderM.

notFound :: ResponderM a -> Application Source #

Respond if no other route responds.

Sets the status to 404.

Requests

param :: ParsableParam a => Text -> ResponderM a Source #

Get a parameter. Looks in query, path, cookie, and body (in that order).

If no parameter is found, or parameter fails to parse, next is called which passes control to subsequent routes and middleware.

paramEither :: ParsableParam a => Text -> ResponderM (Either HttpError a) Source #

Get a parameter or error if missing or parse failure.

paramMaybe :: ParsableParam a => Text -> ResponderM (Maybe a) Source #

Get an optional parameter.

Returns Nothing for missing parameter. Throws HttpError on parse failure.

params :: ResponderM [Param] Source #

Get all parameters from query, path, cookie, and body (in that order).

file :: Text -> ResponderM (FileInfo ByteString) Source #

Get uploaded FileInfo.

If missing parameter or empty file, pass control to subsequent routes and middleware.

fileMaybe :: Text -> ResponderM (Maybe (FileInfo ByteString)) Source #

Get optional uploaded FileInfo.

Nothing is returned for missing parameter or empty file content.

files :: ResponderM [File ByteString] Source #

Get all uploaded files.

fromBody :: FromJSON a => ResponderM a Source #

Get the JSON value from request body.

header :: Text -> ResponderM (Maybe Text) Source #

Get the value of a request Header. Header names are case-insensitive.

headers :: ResponderM [Header] Source #

Get the request headers.

request :: ResponderM Request Source #

Get the WAI Request.

Responses

send :: Response -> ResponderM a Source #

Send a Response.

send $ text "Hello, World!"

Send an html response:

send $ html "<h1>Hello, World!</h1>"

Modify the status:

send $ status status404 $ text "Not Found"

Send a response withHeader:

send $ withHeader (hServer, "Twain + Warp") $ text "Hello"

Send a response withCookie:

send $ withCookie "key" "val" $ text "Hello"

next :: ResponderM a Source #

Pass control to the next route or middleware.

redirect301 :: Text -> Response Source #

Create a redirect response with 301 status (Moved Permanently).

redirect302 :: Text -> Response Source #

Create a redirect response with 302 status (Found).

redirect303 :: Text -> Response Source #

Create a redirect response 303 status (See Other).

text :: Text -> Response Source #

Construct a Text response.