Network.HTTP.Media.Accept

Defines the Accept type class, designed to unify types on the matching functions in the Media module.

Documentation

class Show a => Accept a where

Defines methods for a type whose values can be matched against each other in terms of an HTTP Accept-* header.

This allows functions to work on both the standard Accept header and others such as Accept-Language that still may use quality values.

Minimal complete definition

parseAccept, matches, moreSpecificThan

Methods

parseAccept :: ByteString -> Maybe a

Specifies how to parse an Accept-* header after quality has been handled.

matches :: a -> a -> Bool

Evaluates whether either the left argument matches the right one.

This relation must be a total order, where more specific terms on the left can produce a match, but a less specific term on the left can never produce a match. For instance, when matching against media types it is important that if the client asks for a general type then we can choose a more specific offering from the server, but if a client asks for a specific type and the server only offers a more general form, then we cannot generalise. In this case, the server types will be the left argument, and the client types the right.

For types with no concept of specificity, this operation is just equality.

moreSpecificThan :: a -> a -> Bool

Evaluates whether the left argument is more specific than the right.

This relation must be irreflexive and transitive. For types with no concept of specificity, this is the empty relation (always false).

hasExtensionParameters :: Proxy a -> Bool

Indicates whether extension parameters are permitted after the weight parameter when this type appears in an Accept header. Defaults to false.

Instances

Accept ByteString

Methods

parseAccept :: ByteString -> Maybe ByteString

matches :: ByteString -> ByteString -> Bool

moreSpecificThan :: ByteString -> ByteString -> Bool

hasExtensionParameters :: Proxy ByteString -> Bool

Accept Language

Methods

parseAccept :: ByteString -> Maybe Language

matches :: Language -> Language -> Bool

moreSpecificThan :: Language -> Language -> Bool

hasExtensionParameters :: Proxy Language -> Bool

Accept MediaType

Methods

parseAccept :: ByteString -> Maybe MediaType

matches :: MediaType -> MediaType -> Bool

moreSpecificThan :: MediaType -> MediaType -> Bool

hasExtensionParameters :: Proxy MediaType -> Bool

mostSpecific :: Accept a => a -> a -> a

Evaluates to whichever argument is more specific. Left biased.

data Proxy a

Serves the same purpose as the Proxy type in base, but redefined here in a basic form for older versions of base that do not include it.

Constructors

Proxy