Both your and the previous reply indicate that the blanks I filled in (the "for all" and "derived from" symbols) were indeed as I suspected, and yes I understoo

Both your and the previous reply indicate that the blanks I filled in (the "for all" and "derived from" symbols) were indeed as I suspected, and yes I understood the definition of runST to be as you describe it. But I still don't comprehend their discussion of how defining runST thusly somehow provides safety in the example they say it would automatically detect is disallowed.