1	import Base
2	
3	# Keeps the terminal cursor failure independent from owned error details.
4	type Failure is Data:
5	  TextDecodeFailure{}
6	  ReaderFailure{}
7	  ResourceFailure{}
8	  ArgumentFailure{}
9	
10	# Classifies each failure without losing its public category.
11	type FailureClass is Data:
12	  TextFailure{}
13	  StorageFailure{}
14	  ResourceLimitFailure{}
15	  InvalidArgumentFailure{}
16	
17	# Retains the terminal failure category across repeated cursor reads.
18	def classify(failure: Failure) -> FailureClass:
19	  match failure:
20	    case TextDecodeFailure{}: TextFailure{}
21	    case ReaderFailure{}: StorageFailure{}
22	    case ResourceFailure{}: ResourceLimitFailure{}
23	    case ArgumentFailure{}: InvalidArgumentFailure{}
24	
25	# Produces a stored cursor state and an output classification.
26	def duplicate(failure: Failure) -> Failure & Failure:
27	  match failure:
28	    case TextDecodeFailure{}: (TextDecodeFailure{}, TextDecodeFailure{})
29	    case ReaderFailure{}: (ReaderFailure{}, ReaderFailure{})
30	    case ResourceFailure{}: (ResourceFailure{}, ResourceFailure{})
31	    case ArgumentFailure{}: (ArgumentFailure{}, ArgumentFailure{})