Andrea Rossato wrote:
Now, the state will not be entirely consumed/evaluated by the user, and so it will not become garbage. Am I right?
No. The state cannot become garbage, because there is still a reference to it. As long as runStateT has not returned, any part of the state can still be accessed, so it is not garbage. Completely evaluating the state will not reduce memory consumption in your case, because the list of lists won't be substantially smaller that the thunk to create it. In fact, evaluating this thunk will consume memory.
Where should I force evaluation?
You can't. Your state really is that large, at least in the toy example. You'd need a different data structure ((Array Int ByteString) or (Map Int ByteString) come to mind) and then make that strict. Udo. -- The Seventh Commandments for Technicians: Work thou not on energized equipment, for if thou dost, thy fellow workers will surely buy beers for thy widow and console her in other ways.