I was trying this:
tuple(map(tuple, tuple(((x,y) for x in range(5)) for y in range(3))))
I got this:
(((0, 2), (1, 2), (2, 2), (3, 2), (4, 2)),
((0, 2), (1, 2), (2, 2), (3, 2), (4, 2)),
((0, 2), (1, 2), (2, 2), (3, 2), (4, 2)))
but I expect:
(((0, 0), (1, 0), (2, 0), (3, 0), (4, 0)),
((0, 1), (1, 1), (2, 1), (3, 1), (4, 1)),
((0, 2), (1, 2), (2, 2), (3, 2), (4, 2)))
You're forcing the evaluations in the wrong order. You're building a generator of generators, building a tuple out of the outer generator to build a tuple of generators, and then building tuples out of the inner generators.
By the time you start working with the inner generators, the outer generator has finished iteration, so y is already 2, the value from the last iteration. This is the y value used the entire time you're iterating over the inner generators, so it's the y value used every time you evaluate (x, y).
You need to call tuple on the inner generators as they're produced, to iterate over them and evaluate (x, y) before y changes:
tuple(tuple((x, y) for x in range(5)) for y in range(3))