+data ImportResult =
+ ImportFailed String -- ^ Failure with an error message.
+ | ImportSkipped String -- ^ We processed the file, but didn't import it.
+ -- The reason is contained in the second field.
+ | ImportSucceeded Int -- ^ We did import records, and here's how many.
+ | ImportUnsupported String -- ^ We didn't know how to process this file.
+ -- The second field should contain info.