Examples
// manual gc gc(%f); // status quo heap() // create a symbol x = %(Sym("x")); // is it allocated? heap() // create more symbols y = %(Sym("y")); z = %(Sym("z")); // what do you expect? heap() // switch to automatic gc ... gc(%t) // ... assigning x+2 to z does NOT change the number of // allocated symbols, because ... z: x+2; // ... x+2 creates a value object, which gets deleted automatically, // seeing is believing ... heap() // back to manual gc ... gc(%f); // ... assigning x+2 to z DOES change the number of // allocated symbols, because ... z: x+2; // ... x+2 creates an value object, which gets NOT deleted automatically, // seeing is believing ... heap() // perform manual gc gc() // what's left? heap() // ok, let's finally clean up ... free(x); free(y); free(z); clear x y z // and we are back at? (cf. above) heap() |  |  |