sw-examples: filter-example.sw3

-- load some toy knowledge to test the filter() function:

is-food |bread> => |yes>
is-food |cheese> => |yes>
is-food |steak> => |yes>

is-furniture |chair> => |yes>
is-furniture |table> => |yes>
is-furniture |stool> => |yes>
is-furniture |lounge> => |yes>

is-day-of-week |monday> => |yes>
is-day-of-week |tuesday> => |yes>
is-day-of-week |wednesday> => |yes>
is-day-of-week |thursday> => |yes>
is-day-of-week |friday> => |yes>
is-day-of-week |saturday> => |yes>
is-day-of-week |sunday> => |yes>

is-week-day |monday> => |yes>
is-week-day |tuesday> => |yes>
is-week-day |wednesday> => |yes>
is-week-day |thursday> => |yes>
is-week-day |friday> => |yes>

is-weekend |saturday> => |yes>
is-weekend |sunday> => |yes>

father |John> => |Fred>
occupation |Fred> => |politician>
father |Sam> => |Robert>
occupation |Robert> => |doctor>
father |Emma> => |Jack>
occupation |Jack> => |nurse>


-- put filter() to the test:
filter(|op: is-furniture>, |yes>) shuffle rel-kets[*]

filter(|ops: occupation father>, |nurse>) rel-kets[*]

filter(|op: father>, |*>) rel-kets[*]

filter(|ops: occupation father>, |doctor> + |nurse>) rel-kets[*]

filter(|*>, |doctor> + |nurse>) rel-kets[*]