x : [_]([2],[3],[3],[4])
x = [(a,b,c,d) | a <- [1,2], b <- [3,4] | c <- [5,6], d <- [7,8,9] ]

property t1 = x @ 0 == (1,3,5,7)
property t2 = x @ 2 == (2,3,5,9)
property t3 = x @ 3 == (2,4,6,7)

y = [(a,b,c) | a <- [1,2,3], b <- [1,2] | c <- [1 ... ] ]

property t4 = y @ 3 == (2,2,0)