Network.HTTP.Headers

This module provides the data types for representing HTTP headers, and operations for looking up header values and working with sequences of header values in Requests and Responses. To avoid having to provide separate set of operations for doing so, we introduce a type class HasHeaders to facilitate writing such processing using overloading instead.

Documentation

class HasHeaders x where

HasHeaders is a type class for types containing HTTP headers, allowing you to write overloaded header manipulation functions for both Request and Response data types, for instance.

Minimal complete definition

getHeaders, setHeaders

Methods

getHeaders :: x -> [Header]

setHeaders :: x -> [Header] -> x

Instances

HasHeaders (Response a)

Methods

getHeaders :: Response a -> [Header]

setHeaders :: Response a -> [Header] -> Response a

HasHeaders (Request a)

Methods

getHeaders :: Request a -> [Header]

setHeaders :: Request a -> [Header] -> Request a

data Header

The Header data type pairs header names & values.

Constructors

Header HeaderName String

Instances

Show Header

Methods

showsPrec :: Int -> Header -> ShowS

show :: Header -> String

showList :: [Header] -> ShowS

mkHeader :: HeaderName -> String -> Header

Header constructor as a function, hiding above rep.

hdrName :: Header -> HeaderName

hdrValue :: Header -> String

data HeaderName

HTTP HeaderName type, a Haskell data constructor for each specification-defined header, prefixed with Hdr and CamelCased, (i.e., eliding the - in the process.) Should you require using a custom header, there's the HdrCustom constructor which takes a String argument.

Encoding HTTP header names differently, as Strings perhaps, is an equally fine choice..no decidedly clear winner, but let's stick with data constructors here.

Constructors

HdrCacheControl

HdrConnection

HdrDate

HdrPragma

HdrTransferEncoding

HdrUpgrade

HdrVia

HdrAccept

HdrAcceptCharset

HdrAcceptEncoding

HdrAcceptLanguage

HdrAuthorization

HdrCookie

HdrExpect

HdrFrom

HdrHost

HdrIfModifiedSince

HdrIfMatch

HdrIfNoneMatch

HdrIfRange

HdrIfUnmodifiedSince

HdrMaxForwards

HdrProxyAuthorization

HdrRange

HdrReferer

HdrUserAgent

HdrAge

HdrLocation

HdrProxyAuthenticate

HdrPublic

HdrRetryAfter

HdrServer

HdrSetCookie

HdrTE

HdrTrailer

HdrVary

HdrWarning

HdrWWWAuthenticate

HdrAllow

HdrContentBase

HdrContentEncoding

HdrContentLanguage

HdrContentLength

HdrContentLocation

HdrContentMD5

HdrContentRange

HdrContentType

HdrETag

HdrExpires

HdrLastModified

HdrContentTransferEncoding

MIME entity headers (for sub-parts)

HdrCustom String

Allows for unrecognised or experimental headers.

Instances

Eq HeaderName

Methods

(==) :: HeaderName -> HeaderName -> Bool

(/=) :: HeaderName -> HeaderName -> Bool

Show HeaderName

Methods

showsPrec :: Int -> HeaderName -> ShowS

show :: HeaderName -> String

showList :: [HeaderName] -> ShowS

insertHeader :: HasHeaders a => HeaderSetter a

insertHeader hdr val x inserts a header with the given header name and value. Does not check for existing headers with same name, allowing duplicates to be introduce (use replaceHeader if you want to avoid this.)

insertHeaderIfMissing :: HasHeaders a => HeaderSetter a

insertHeaderIfMissing hdr val x adds the new header only if no previous header with name hdr exists in x.

insertHeaders :: HasHeaders a => [Header] -> a -> a

insertHeaders hdrs x appends multiple headers to x's existing set.

retrieveHeaders :: HasHeaders a => HeaderName -> a -> [Header]

retrieveHeaders hdrNm x gets a list of headers with HeaderName hdrNm.

replaceHeader :: HasHeaders a => HeaderSetter a

replaceHeader hdr val o replaces the header hdr with the value val, dropping any existing

findHeader :: HasHeaders a => HeaderName -> a -> Maybe String

findHeader hdrNm x looks up hdrNm in x, returning the first header that matches, if any.

lookupHeader :: HeaderName -> [Header] -> Maybe String

lookupHeader hdr hdrs locates the first header matching hdr in the list hdrs.

parseHeader :: String -> Result Header

parseHeader headerNameAndValueString tries to unscramble a header: value pairing and returning it as a Header.

parseHeaders :: [String] -> Result [Header]

parseHeaders hdrs takes a sequence of strings holding header information and parses them into a set of headers (preserving their order in the input argument.) Handles header values split up over multiple lines.

headerMap :: [(String, HeaderName)]

headerMap is a straight assoc list for translating between header names and values.

type HeaderSetter a = HeaderName -> String -> a -> a