=> what library does SSU need loaded

I’ve installed the latest development version for windows and tried to use SSU operator – but its not recognized.

I recall that its not autoloaded, but can’t find the library that needs to be included. I didn’t see it mentioned in the online documentation.

Can you help me recall …

thanks,

Dan

It just works for me with 8.3.21. Which version exactly are you using?

What happens, exactly?

Welcome to SWI-Prolog (threaded, 64 bits, version 8.3.21)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit https://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- between(X), between(1, 3, X) => true.
ERROR: Unknown procedure: (=>)/2 (DWIM could not correct goal)

I downloaded the latest development version

It doesn’t work like this I thought? Replace the => with :- and it should be still broken:

?- between(X), between(1, 3, X) :- true.

@jan as a matter of fact, the error message with :- is more useful. Here is the full output that I see:

Welcome to SWI-Prolog (threaded, 64 bits, version 8.3.21-18-g0ce6d17ea)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit https://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- between(X), between(1, 3, X) :- true.
ERROR: Unknown procedure: (:-)/2
ERROR:   Rules must be loaded from a file
ERROR:   See FAQ at https://www.swi-prolog.org/FAQ/ToplevelMode.txt
ERROR: In:
ERROR:    [9] throw(error(existence_error(procedure,...),_24762))
ERROR:    [6] correct_goal((...,... :- true),user,['X'=_24822],_24798) at /Users/e911899/bin/swipl/lib/swipl/boot/dwim.pl:85
ERROR: 
ERROR: Note: some frames are missing due to last-call optimization.
ERROR: Re-run your program in debug mode (:- debug.) to get more detail.
?- between(X), between(1, 3, X) => true.
ERROR: Unknown procedure: (=>)/2 (DWIM could not correct goal)

ok, thanks.

I guess ideally someone would take initiative and make a pull request to add =>/2 and =>/1 to unknown_proc_msg/1 in boot/messages.pl (around line 224) and update the linked FAQ entry at https://www.swi-prolog.org/FAQ/ToplevelMode.txt.

Thanks for being so precise. I’ll add a line. =>/1 doesn’t exist, so we only need =>/2.

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