Moduleservant-0.20.2Haskell2010

Servant.API.ResponseHeaders

This module provides facilities for adding headers to a response.

Example1 expression

>>> 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).

3 types
5 classes
5 values

Packageservant-0.20.2
Exports14
LanguageHaskell2010
LicenceBSD-3-Clause
SourceResponseHeaders.hs

datadata Headers (ls :: [Type]) a

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

Constructors

Headers
- getResponse :: a
  The underlying value of a Headers
- getHeadersHList :: HList ls
  HList of headers.

Instances6AddHeader, Functor, NFData, GetHeaders, HasStatus, StatusOf

(KnownSymbol h, ToHttpApiData v) => AddHeader mods h v (Headers (fst ': rest) a) (Headers (Header' mods h v ': fst ': rest) a)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
Functor (Headers ls)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
(NFDataHList ls, NFData a) => NFData (Headers ls a)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
GetHeaders' hs => GetHeaders (Headers hs a)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
HasStatus a => HasStatus (Headers ls a)Defined in servant-0.20.2 · Servant.API.UVerb
type StatusOf (Headers ls a) = StatusOf aDefined in servant-0.20.2 · Servant.API.UVerb

datadata ResponseHeader (sym :: Symbol) a

Constructors

Instances4Functor, Eq, Show, NFData

Functor (ResponseHeader sym)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
Eq a => Eq (ResponseHeader sym a)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
Show a => Show (ResponseHeader sym a)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
NFData a => NFData (ResponseHeader sym a)Defined in servant-0.20.2 · Servant.API.ResponseHeaders

class

class AddHeader (mods :: [Type]) (h :: Symbol) v orig new | mods h v orig -> new, new -> mods, new -> h, new -> v, new -> orig where

Instances4AddHeader

(KnownSymbol h, ToHttpApiData v, new ~ Headers '[Header' mods h v] a) => AddHeader mods h v a newDefined in servant-0.20.2 · Servant.API.ResponseHeaders
AddHeader mods h v old new => AddHeader mods h v (Union '[old]) (Union '[new])Defined in servant-0.20.2 · Servant.API.ResponseHeaders
(AddHeader mods h v old new, AddHeader mods h v (Union oldrest) (Union newrest), oldrest ~ (a ': as), newrest ~ (b ': bs)) => AddHeader mods h v (Union (old ': a ': as)) (Union (new ': b ': bs))Defined in servant-0.20.2 · Servant.API.ResponseHeaders
(KnownSymbol h, ToHttpApiData v) => AddHeader mods h v (Headers (fst ': rest) a) (Headers (Header' mods h v ': fst ': rest) a)Defined in servant-0.20.2 · Servant.API.ResponseHeaders

valueaddHeader :: AddHeader '[Optional, Strict] h v orig new => v -> orig -> new

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

A simple value is wrapped in "Headers '[hdr]":

Example2 expressions

>>> let example0 = addHeader 5 "hi" :: Headers '[Header "someheader" Int] String;>>> getHeaders example0[("someheader","5")]

A value that already has a header has its new header *prepended* to the existing list:

Example3 expressions

>>> 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.

valueaddHeader' :: AddHeader mods h v orig new => v -> orig -> new

Same as addHeader but works with Header', so it's possible to use any mods.

valuenoHeader :: AddHeader '[Optional, Strict] h v orig new => orig -> new

Deliberately do not add a header to a value.

Example2 expressions

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

valuenoHeader' :: AddHeader mods h v orig new => orig -> new

Same as noHeader but works with Header', so it's possible to use any mods.

classclass HasResponseHeader (h :: Symbol) a (headers :: [Type]) where

Instances2HasResponseHeader

HasResponseHeader h a (Header' mods h a ': rest)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
HasResponseHeader h a rest => HasResponseHeader h a (first ': rest)Defined in servant-0.20.2 · Servant.API.ResponseHeaders

valuelookupResponseHeader

:: HasResponseHeader h a headers
=> Headers headers r
-> ResponseHeader h a

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

Example3 expressions

>>> 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" IntHeader 5

Example1 expression

>>> lookupResponseHeader example2 :: ResponseHeader "1st" BoolHeader 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:

Example2 expressions

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

classclass BuildHeadersTo (hs :: [Type]) where

Methods

buildHeadersTo :: [Header] -> HList hs

Instances2BuildHeadersTo

BuildHeadersTo '[]Defined in servant-0.20.2 · Servant.API.ResponseHeaders
(FromHttpApiData v, BuildHeadersTo xs, KnownSymbol h) => BuildHeadersTo (Header' mods h v ': xs)Defined in servant-0.20.2 · Servant.API.ResponseHeaders

classclass GetHeaders ls where

Methods

getHeaders :: ls -> [Header]

Instances2GetHeaders

GetHeadersFromHList hs => GetHeaders (HList hs)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
GetHeaders' hs => GetHeaders (Headers hs a)Defined in servant-0.20.2 · Servant.API.ResponseHeaders

classclass GetHeaders' (hs :: [Type]) where

Auxiliary class for GetHeaders (Headers hs a) instance

Instances2GetHeaders'

GetHeaders' '[]Defined in servant-0.20.2 · Servant.API.ResponseHeaders
This instance is an optimisation
(KnownSymbol h, GetHeadersFromHList rest, ToHttpApiData v) => GetHeaders' (Header' mods h v ': rest)Defined in servant-0.20.2 · Servant.API.ResponseHeaders

familytype family HeaderValMap (f :: Type -> Type) (xs :: [Type]) :: [Type] where

Equations

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

datadata HList (a :: [Type]) where

Constructors

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

Instances2NFData, GetHeaders

NFDataHList xs => NFData (HList xs)Defined in servant-0.20.2 · Servant.API.ResponseHeaders
GetHeadersFromHList hs => GetHeaders (HList hs)Defined in servant-0.20.2 · Servant.API.ResponseHeaders