13.33.2 Other Changes

• Windows 8.1 is no longer supported since it has reached its end of life (https://docs.microsoft.com/en-us/lifecycle/products/windows-81). This makes Windows 10 the minimum supported version of Windows.
• Improve performance of call_cleanup/2, which could be arbitrarily slow.
• The Cleanup goal of call_cleanup/2 is now called as if by once/1. This means that it cannot leave any choice points behind.

  For Cleanup goals called as the result of !, this change was introduced already in release 4.7.

  The documentation used to warn that if exiting non-determinately from the Cleanup “unexpected behavior may result”. Now this is no longer possible. This is an incompatible change but we do not expect this to affect any correct code.

• Interpreted calls to meta-predicates, e.g. by call/1 and similar constructs, are faster.
• The built-in length/2 used to loop for certain incorrect calls, like length([a,b|L],L). Instead it will now immediately throw an out of memory error, which is what would eventually have happened anyway. This is similar to how some other incorrect argument combinations are already handled.
• The top level will now ask the user for how to proceed if there are pending alternatives (choicepoints), also when the latest solution did not produce any variable bindings to display. Prior to release 4.8, the top level would ignore any further solutions if no variable bindings were displayed, even if the top-level goal succeeded nondeterminately.

  Prior to release 4.8 the behavior was:

  | ?- (write('Hello\n'); write('World\n')).
  Hello
  yes
  

  i.e. the second alternative was never run.

  In release 4.8 this changed so that the user can decide how to proceed after the first solution:

  | ?- (write('Hello\n'); write('World\n')).
  Hello
  true ? ;
  World
  yes
  

  i.e. the second alternative is run if the user asks for more solutions.

• The way streams and sub-processes interact has been improved. In particular it is now possible to start an interactive sub-process, like a shell, with process:process_create/[2,3], and to let the sub-process use the standard streams in the expected way.

  The following changes have been made to enable this new feature:

  • SICStus will no longer “read ahead” on the standard input stream when it is connected to a terminal or similar device, or when sicstus is invoked with the -i option. This means that the SICStus process will no longer “steal” input from the sub-process while the sub-process in running (unless something, like the SICStus top level, also tries to read from the standard input stream).
  • process:process_create/3 has changed so that the stdin(…) option always defaults to std as documented. Prior to this release the default value was null if a wait/1 option was specified. If you want to use a null stream, you can explicitly pass the option stdin(null) to process:process_create/3.
  • process:process_create/[2,3], on Windows, now gives the sub-process access to the parent (SICStus) process’s “console window”. This lets the sub-process read from, and write to, the console window, which is particularly useful if the sub-process is an interactive program, like a shell.
• On UNIX (e.g. Linux and macOS) the stability has been improved when open/[3,4] leaves too many files open.
• A new resource_error has been added, file_handle, which is thrown when attempting to open too many files. See Resource Errors in the SICStus Prolog Manual for details.
• The unsupported SICStus 3 compatibility predicate prolog:undo/1 has been removed. In many cases call_cleanup/2 can be used for a similar purpose. Contact us if this is a problem.
• MiniZinc: the solver configuration file, sicstus.msc, has been changed so that no files need to be added in the MiniZinc installation, and the SICStus bin/ directory no longer need to be on the PATH. Instead the path to sicstus.msc can be passed directly to the command line tool minizinc (with --solver), or the library/zinc/ directory can be added to the the MiniZincIDE preferences. See Zinc Prerequisites in the SICStus Prolog Manual for details.
• The predicates bags:length/3, bags:member/3 and bags:memberchk/3 have been deprecated, and may be removed in a future release. They have been replaced by bags:bag_length/3, bags:bag_member/3 and bags:bag_memberchk/3, respectively.