Documentation

Exception type for Win32 errors.

This type will be thrown as an extensible exception when a foreign call out to part of the Win32 indicates that an error has occurred. In most cases you should wrap an IO computation in a call to tryWin32.

The following example uses the custom createFile function described in System.Win32.Error.Foreign:

eHandle <- do
    h <- E.tryWin32 $ createFile "c:\\missing.txt" gENERIC_READ oPEN_EXISTING
    -- perform other actions
    return h
case eHandle of
  Right handle -> do
    -- do something with the file handle
  Left w32Err -> do
    case E.errCode w32Err of
      E.InvalidHandle -> do
        -- perform cleanup
      -- handle other error codes.
    T.putStrLn $ E.systemMessage w32Err

Actions calling out to Win32 may throw exceptions. Wrapping the action in tryWin32 will catch Win32Exception exceptions, but will allow any other exception type to pass through.

Convert an ErrCode into a DWORD.

Convert a DWORD into an ErrCode. Values which don't have a corresponding constructor will end up becoming an Other.

Win32 actions typically return an error code to indicate success or failure. These codes are intended to be globally unique, though there may be some overlap. MSDN documents which errors may be returned by any given action.

The naming of errors follows a convention. An error such as ERROR_SUCCESS becomes Success, ERROR_FILE_NOT_FOUND becomes FileNotFound, and so on. There are thousands of errors, so it would be impractical to add them all. The Other constructor is used to represent error codes which are not handled specifically.

User's of this library are encouraged to submit new error codes. Add new entries to System.Win32.Errors.Mapping. Send your pull requests along with a link to relevent documentation to https://github.com/mikesteele81/Win32-errors.git.