(I know I'm asking some noddy questions, but hey, that's what this list is for...) How do I create IOError exceptions? System.IO.Error has two functions that create IOErrors: userError and mkIOError. However, both of them take a String (I assume containing a description of the problem), and mkIOError takes optional Handle and FilePath args. http://www.haskell.org/ghc/docs/latest/html/base/System.IO.Error.html What I'd like to do is stuff some more information into the exception (a bit like Java exceptions), along the lines of:
mkIOError :: a -> IOError
where I could choose to use it like this (ociHandleAlloc is a foreign C function):
handleAlloc2 handleType env ptr = do rc <- ociHandleAlloc env ptr handleType 0 0 if rc < 0 then ioError (mkIOError ("Couldn't allocate handle", rc)) else peek ptr
When I catch the exception (currently in main) I would like to interrogate it to get the values I stuffed in it (in this case a (String, Int) tuple), and then do some error reporting by calling another function which decodes the error number. Is this the wrong way to go about error handling? Or is it relatively simple to create your own IOErrors? Have I missed something in the docs? ***************************************************************** The information in this email and in any attachments is confidential and intended solely for the attention and use of the named addressee(s). This information may be subject to legal professional or other privilege or may otherwise be protected by work product immunity or other legal rules. It must not be disclosed to any person without our authority. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, you are not authorised to and must not disclose, copy, distribute, or retain this message or any part of it. *****************************************************************