Generators

A function that contains a yield statement is called ‘generator function’. When a generator function is called, it does not execute the function body, instead it returns a new suspended generator. The returned generator can be resumed through the resume statement while it is alive. The yield keyword, suspends the execution of a generator and optionally returns the result of an expression to the function that resumed the generator. The generator dies when it returns, this can happen through an explicit return statement or by exiting the function body; If an unhandled exception (or runtime error) occurs while a generator is running, the generator will automatically die. A dead generator cannot be resumed anymore.

function geny(n)
{
    for(local i=0;i<n;i+=1)
        yield i;
    return null;
}

local gtor=geny(10);
local x;
while(x=resume gtor) print(x+”\n”);
		

the output of this program will be

0
1
2
3
4
5
6
7
8
9