I was wondering how you would represent an inventory? For instance, how can you say a library has a certain number of each kind of book?

I think I have it:

Table: library_inventory (^library ^work ^quantity)
^createfact((^library own ^work) number ^quantity)
Data:
“Dutch Royal Archives”  “Fahrenheit 451”  1
“George Peabody Library”  “2001: A Space Odyssey”  1
“Kremsmuenster Abbey Library”  “Neuromancer”  2

That should be:

Table: library_inventory (^library ^work ^quantity)
^createfact((^library own ^work) count ^quantity)
Data:
“Dutch Royal Archives”  “Fahrenheit 451”  1
“George Peabody Library”  “2001: A Space Odyssey” 1
“Kremsmuenster Abbey Library”  “Neuromancer”  2

I tried these queries on it:

#! has book
a: ( \[has book \] )  if ( ^query( direct_svo “George Peabody Library” own “2001: A Space Odyssey”) ) { Yes. } else { No. }

#! book number
a: ( \[book number \] )  @0 = ^query( direct_svo “Dutch Royal Archives” count “Fahrenheit 451”) They have this many of Fahrenheit 451 @0object

[has book] returned

“Yes.”

[book number] returned

“They have this many of Fahrenheit 451”

Is there a way to get the value inside @0 to print to the user?

I think I see what is going on. There is something wrong with the way the table is set up. Hmm…

Looks like I won’t need this exact functionality after all. But I would like to know what I am doing wrong, in case I need to build my own tables on future. The more examples of there are of these on the forum, the better.

so… you store facts like this:

^createfact((^library own ^work) count ^quantity)

yet you try to retrieve facts like this:
^query( direct_svo “Dutch Royal Archives” count “Fahrenheit 451”)

which clearly does not match your representation.

^createfact( ^library ^work ^count) 

would be a much simpler representation, allowing you to ask how many copies of a work a library has, or if it fails, that is has none.

Thanks for your help Bruce. I was overcomplicating things as usual.

I’ve been messing around with this again. Here’s some code that might help a newbie get started

Adding and removing facts one at a time

Bug fix for the above:

Replace:

^delete(@0)

With:

^delete(^query( direct_sv “Dutch Royal Archives” “Lord of the Rings”))

Here’s some working code from the Fact Manual, ADVANCED FACTS, Facts of Facts