catch/4

Documentation
- Reference manual
  - The SWI-Prolog library
    - library(exceptions): Exception classification
- Packages

Availability::- use_module(library(exceptions)).(can be autoloaded)

catch(:Goal, +ExceptionType, ?Ball, :Recover)

As catch/3, only catching exceptions for which exception(ErrorType,Ball) is true. See error/2. For example, the code below properly informs the user some file could not be processed due do some issue with File, while propagating on all other reasons while process/1 could not be executed.

    catch(process(File), file_error, Ball,
          file_not_processed(File, Ball))

file_not_processed(File, Ball) :-
    message_to_string(Ball, Msg),
    format(user_error, 'Could not process ~p: ~s', [File, Msg]).