More specific exception handling in Riak

[sanketr]

Folks,

It seems that RiakException constructor doesn't expose the sub-types of exceptions. There is really no good way to do a user-friendly error handling if we don't know what sub-type of exception this is. For example, given TypeException, I could tell the user that the requested data doesn't exist. NetException on the other hand is some kind of outage message in my case. This is very, very useful, and so, will really appreciate exposing the constructors. This is my current exception handling code - will like to be able to pattern match on RiakException and do appropriate error handling instead of using RiakException show:

procRiakException :: SomeException -> Maybe RiakException
procRiakException = fromException

procException :: SomeException -> (Int,T.Text)
procException e = case (procRiakException e) of
  Just ex -> (2, T.pack . show $ ex)
  Nothing -> (1, T.pack . displayException $ e)

[sanketr]

On further investigation, it seems that ErrorResponse is where the Riak exceptions are handled. It is defined as Exception elsewhere but not exported. So, probably this is the correct exception to look at for making visible to users of the library.