Network.Wai.Middleware.Catch

Exception handling for Wai and Warp.

By default Warp not handles exceptions well. It just log them to console. This package - an attempt to solve the problem.

The only drawback stems from the basic advantages of Haskell - laziness. All errors within Wai ResponseBuilder will not be caught. Thus, the following code will not work:

 ... return $ responseLBS undefined ...

To ensure catch all errors, you need to consume all data before feeding the builder.

Middleware

protect

Arguments

:: [ResponseHandler]

Wrapped handlers. See mkHandler.

-> Middleware

Protect Middleware chain from exceptions. This acts like catches, but uses own handler type for simplicity.

If an exception is not handled, it is thrown further. To handle this use protect'.

protect'

Arguments

:: Exception e

=> [ResponseHandler]

Wrapped handlers. See mkHandler.

-> (e -> Application)

Default handler

-> Middleware

"Harden" version of protect.

Handlers

data ResponseHandler

Handler wrapper. For polymorphic exceptions. If an exception is not handled, it is thrown to default handler.

 protect' [...] defHandler

Constructors

forall e . Exception e => ResponseHandler (e -> Application)

mkHandler

Arguments

:: forall e . Exception e

=> (e -> Application)

-> ResponseHandler

Helper for make RequestHandler

 protect [mkHandler myHandler] $ ...

defHandler :: SomeException -> Application

Default handler.