i1 : x = tally {a,b,b,c,c,c} o1 = Tally{a => 1} b => 2 c => 3 o1 : Tally |
i2 : y = tally {a,a,a,b,b,c} o2 = Tally{a => 3} b => 2 c => 1 o2 : Tally |
i3 : x' = new VirtualTally from x o3 = VirtualTally{a => 1} b => 2 c => 3 o3 : VirtualTally |
i4 : y' = new VirtualTally from y o4 = VirtualTally{a => 3} b => 2 c => 1 o4 : VirtualTally |
i5 : x-y o5 = Tally{c => 2} o5 : Tally |
i6 : x'-y' o6 = VirtualTally{a => -2} c => 2 o6 : VirtualTally |
The object VirtualTally is a type, with ancestor classes HashTable < Thing.