servant-0.18.2: A family of combinators for defining webservices APIs
Safe HaskellNone
LanguageHaskell2010

Servant.API.ResponseHeaders

Description

This module provides facilities for adding headers to a response.

>>> let headerVal = addHeader "some-url" 5 :: Headers '[Header "Location" String] Int

The value is added to the header specified by the type (Location in the example above).

Synopsis

Documentation

data Headers ls a Source #

Response Header objects. You should never need to construct one directly. Instead, use addOptionalHeader.

Constructors

Headers 

Fields

Instances

Instances details
(KnownSymbol h, ToHttpApiData v) => AddHeader h v (Headers (fst ': rest) a) (Headers (Header h v ': (fst ': rest)) a) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

addOptionalHeader :: ResponseHeader h v -> Headers (fst ': rest) a -> Headers (Header h v ': (fst ': rest)) a

Functor (Headers ls) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

fmap :: (a -> b) -> Headers ls a -> Headers ls b #

(<$) :: a -> Headers ls b -> Headers ls a #

(NFDataHList ls, NFData a) => NFData (Headers ls a) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

rnf :: Headers ls a -> () #

GetHeaders' hs => GetHeaders (Headers hs a) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

getHeaders :: Headers hs a -> [Header] Source #

data ResponseHeader (sym :: Symbol) a Source #

Instances

Instances details
Functor (ResponseHeader sym) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

fmap :: (a -> b) -> ResponseHeader sym a -> ResponseHeader sym b #

(<$) :: a -> ResponseHeader sym b -> ResponseHeader sym a #

Eq a => Eq (ResponseHeader sym a) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

(==) :: ResponseHeader sym a -> ResponseHeader sym a -> Bool #

(/=) :: ResponseHeader sym a -> ResponseHeader sym a -> Bool #

Show a => Show (ResponseHeader sym a) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

showsPrec :: Int -> ResponseHeader sym a -> ShowS #

show :: ResponseHeader sym a -> String #

showList :: [ResponseHeader sym a] -> ShowS #

NFData a => NFData (ResponseHeader sym a) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

rnf :: ResponseHeader sym a -> () #

class AddHeader h v orig new | h v orig -> new, new -> h, new -> v, new -> orig Source #

Minimal complete definition

addOptionalHeader

Instances

Instances details
(KnownSymbol h, ToHttpApiData v, new ~ Headers '[Header h v] a) => AddHeader h v a new Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

addOptionalHeader :: ResponseHeader h v -> a -> new

(KnownSymbol h, ToHttpApiData v) => AddHeader h v (Headers (fst ': rest) a) (Headers (Header h v ': (fst ': rest)) a) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

addOptionalHeader :: ResponseHeader h v -> Headers (fst ': rest) a -> Headers (Header h v ': (fst ': rest)) a

addHeader :: AddHeader h v orig new => v -> orig -> new Source #

addHeader adds a header to a response. Note that it changes the type of the value in the following ways:

  1. A simple value is wrapped in "Headers '[hdr]":
>>> let example1 = addHeader 5 "hi" :: Headers '[Header "someheader" Int] String;
>>> getHeaders example1
[("someheader","5")]
  1. A value that already has a header has its new header *prepended* to the existing list:
>>> let example1 = addHeader 5 "hi" :: Headers '[Header "someheader" Int] String;
>>> let example2 = addHeader True example1 :: Headers '[Header "1st" Bool, Header "someheader" Int] String
>>> getHeaders example2
[("1st","true"),("someheader","5")]

Note that while in your handlers type annotations are not required, since the type can be inferred from the API type, in other cases you may find yourself needing to add annotations.

noHeader :: AddHeader h v orig new => orig -> new Source #

Deliberately do not add a header to a value.

>>> let example1 = noHeader "hi" :: Headers '[Header "someheader" Int] String
>>> getHeaders example1
[]

class HasResponseHeader h a headers Source #

Minimal complete definition

hlistLookupHeader

Instances

Instances details
HasResponseHeader h a rest => HasResponseHeader h a (first ': rest) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

hlistLookupHeader :: HList (first ': rest) -> ResponseHeader h a

HasResponseHeader h a (Header h a ': rest) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

hlistLookupHeader :: HList (Header h a ': rest) -> ResponseHeader h a

lookupResponseHeader :: HasResponseHeader h a headers => Headers headers r -> ResponseHeader h a Source #

Look up a specific ResponseHeader, without having to know what position it is in the HList.

>>> let example1 = addHeader 5 "hi" :: Headers '[Header "someheader" Int] String
>>> let example2 = addHeader True example1 :: Headers '[Header "1st" Bool, Header "someheader" Int] String
>>> lookupResponseHeader example2 :: ResponseHeader "someheader" Int
Header 5
>>> lookupResponseHeader example2 :: ResponseHeader "1st" Bool
Header True

Usage of this function relies on an explicit type annotation of the header to be looked up. This can be done with type annotations on the result, or with an explicit type application. In this example, the type of header value is determined by the type-inference, we only specify the name of the header:

>>> :set -XTypeApplications
>>> case lookupResponseHeader @"1st" example2 of { Header b -> b ; _ -> False }
True

Since: 0.15

class BuildHeadersTo hs where Source #

Methods

buildHeadersTo :: [Header] -> HList hs Source #

Note: if there are multiple occurrences of a header in the argument, the values are interspersed with commas before deserialization (see RFC2616 Sec 4.2)

Instances

Instances details
BuildHeadersTo ('[] :: [Type]) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

buildHeadersTo :: [Header] -> HList '[] Source #

(FromHttpApiData v, BuildHeadersTo xs, KnownSymbol h) => BuildHeadersTo (Header h v ': xs) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

buildHeadersTo :: [Header0] -> HList (Header h v ': xs) Source #

class GetHeaders ls where Source #

Methods

getHeaders :: ls -> [Header] Source #

Instances

Instances details
GetHeadersFromHList hs => GetHeaders (HList hs) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

getHeaders :: HList hs -> [Header] Source #

GetHeaders' hs => GetHeaders (Headers hs a) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

getHeaders :: Headers hs a -> [Header] Source #

class GetHeaders' hs Source #

Auxiliary class for GetHeaders (Headers hs a) instance

Minimal complete definition

getHeaders'

Instances

Instances details
GetHeaders' ('[] :: [Type]) Source #

This instance is an optimisation

Instance details

Defined in Servant.API.ResponseHeaders

Methods

getHeaders' :: Headers '[] a -> [Header]

(KnownSymbol h, GetHeadersFromHList rest, ToHttpApiData v) => GetHeaders' (Header h v ': rest) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

getHeaders' :: Headers (Header h v ': rest) a -> [Header0]

type family HeaderValMap (f :: * -> *) (xs :: [*]) where ... Source #

Equations

HeaderValMap f '[] = '[] 
HeaderValMap f (Header h x ': xs) = Header h (f x) ': HeaderValMap f xs 

data HList a where Source #

Constructors

HNil :: HList '[] 
HCons :: ResponseHeader h x -> HList xs -> HList (Header h x ': xs) 

Instances

Instances details
NFDataHList xs => NFData (HList xs) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

rnf :: HList xs -> () #

GetHeadersFromHList hs => GetHeaders (HList hs) Source # 
Instance details

Defined in Servant.API.ResponseHeaders

Methods

getHeaders :: HList hs -> [Header] Source #