isa - create an instance frame
new-instance-frame isa instance-frame-name [with slot-list]!
Create a new instanceframe with name new-instance-frame and optionally with slot values defined by slot-list. Isa is a 2-arity predicate.
The slot list consists of a slot name, followed by a ':'and a value. Slot values are separated by ';'. The final slot value should be terminated by a '!'.
Creation of a new instance frame triggers the if_new dæmon.
Given the generic definition of cylinder, some instances can be defined as:
c isa cylinder with height: 2; radius: 4! d isa cylinder with colour: red! e isa cylinder!
Slot values are stored in Prolog's database as value clauses. For example, the following clauses are asserted into the database as a result of the three directives above.
value(c, isa, [cylinder]). value(c, height, 2). value(c, radius, 4). value(d, isa, [cylinder]). value(d, colour, red). value(e, isa, [cylinder]).
ako, if_new