Network.HTTP.Lucu.Abortion

Aborting the computation of Network.HTTP.Lucu.Resource.Resource in any IO monads or arrows.

Documentation

abort :: MonadIO m => StatusCode -> [(String, String)] -> Maybe String -> m a

Computation of abort status headers msg aborts the Network.HTTP.Lucu.Resource.Resource monad with given status, additional response headers, and optional message string.

What this really does is to throw a special Exception. The exception will be caught by the Lucu system.

1. If the Network.HTTP.Lucu.Resource.Resource is in the /Deciding Header/ or any precedent states, it is possible to use the status and such like as a HTTP response to be sent to the client.
2. Otherwise the HTTP response can't be modified anymore so the only possible thing the system can do is to dump it to the stderr. See cnfDumpTooLateAbortionToStderr.

Note that the status code doesn't have to be an error code so you can use this action for redirection as well as error reporting e.g.

 abort MovedPermanently
       [("Location", "http://example.net/")]
       (Just "It has been moved to example.net")

abortPurely :: StatusCode -> [(String, String)] -> Maybe String -> a

This is similar to abort but computes it with unsafePerformIO.

abortSTM :: StatusCode -> [(String, String)] -> Maybe String -> STM a

Computation of abortSTM status headers msg just computes abort in a Control.Monad.STM.STM monad.

abortA :: ArrowIO a => a (StatusCode, ([(String, String)], Maybe String)) c

Computation of abortA -< (status, (headers, msg)) just computes abort in an ArrowIO.