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GHC 9.14.1 · lts/ghc-9.14.x · 3e2d568 · 2026-10-11

Modulehttp-semantics-0.4.1Haskell2010

Network.HTTP.Semantics

Library for HTTP Semantics (RFC9110), version-independent common parts. For low-level headers, Token is used. For upper-level headers, Network.HTTP.Types.HeaderName should be used.

  • 21 types
  • 3 values
typetype TrailersMaker = Maybe ByteString -> IO NextTrailersMaker
#

Trailers maker. A chunks of the response body is passed with Just. The maker should update internal state with the ByteString and return the next trailers maker. When response body reaches its end, Nothing is passed and the maker should generate trailers. An example:

{-# LANGUAGE BangPatterns #-}
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as C8
import Crypto.Hash (Context, SHA1) -- cryptonite
import qualified Crypto.Hash as CH

-- Strictness is important for Context.
trailersMaker :: Context SHA1 -> Maybe ByteString -> IO NextTrailersMaker
trailersMaker ctx Nothing = return $ Trailers [("X-SHA1", sha1)]
  where
    !sha1 = C8.pack $ show $ CH.hashFinalize ctx
trailersMaker ctx (Just bs) = return $ NextTrailersMaker $ trailersMaker ctx'
  where
    !ctx' = CH.hashUpdate ctx bs

Usage example:

let h2rsp = responseFile ...
    maker = trailersMaker (CH.hashInit :: Context SHA1)
    h2rsp' = setResponseTrailersMaker h2rsp maker
datadata OutBodyIface
#

Constructors

  • OutBodyIface
    • outBodyUnmask :: forall x. IO x -> IO x

      Unmask exceptions in the thread spawned for the request body

      This is used in the client: we spawn the new thread for the request body with exceptions masked, and provide the body of OutBodyStreamingIface with a callback to unmask them again (typically after installing an exception handler).

      Unmasking in the server is a no-op, as here the scope of the thread that is spawned for the server is the entire handler, not just the response streaming body.

    • outBodyPush :: Builder -> IO ()

      Push a new chunk

      In http2, there is no direct correspondence between chunks and the resulting DATA frames sent: the chunks are collected (written to an internal write buffer) until we can fill a frame.

      See also outBodyFlush.

    • outBodyPushFinal :: Builder -> IO ()

      Push the final chunk

      Using this function instead of outBodyPush can be used to guarantee that the final HTTP2 DATA frame is marked end-of-stream; with outBodyPush it may happen that an additional empty DATA frame is used for this purpose. Additionally, after calling this function, outBodyCancel will be a no-op.

    • outBodyCancel :: Maybe SomeException -> IO ()

      Cancel the stream

      Sends a RST_STREAM to the peer. If cancelling as the result of an exception, a Just should be provided which specifies the exception which will be stored locally as the reason for cancelling the stream; in this case, the error code sent with the RST_STREAM will be INTERNAL_ERROR (see https://datatracker.ietf.org/doc/html/rfc7540#section-7). If Nothing is given, the error code will be CANCEL.

      If there is a partially constructed DATA frame at the time of cancellation, this frame is discarded. If this is undesirable, you should call outBodyFlush prior to cancelling.

    • outBodyFlush :: IO ()

      Flush

      This can be used to emit a DATA frame with the data collected so far (using outBodyPush), even if that DATA frame has not yet reached the maximum frame size. Calling outBodyFlush unnecessarily can therefore result in excessive overhead from frame headers.

      If no data is available to send, this is a no-op.

module Network.HTTP.Semantics.Token