Cached operations in EOL

To simulate derived properties, EOL supports cached operations. A cached operation - parameter-less operation annotated with a @cached annotation - is only executed once: subsequent calls return the same result without executing its body again. An example that calculates the Fibonacci number of a given Integer follows:

15.fib();

@cached
operation Integer fib() : Integer {
	if (self = 1 or self = 0) {
		return 1;
	}
	else {
		return (self-1).fib() + (self-2).fib();
	}
}