| # list comprehensions |
| |
| # The first for clause is resolved outside the comprehension block. |
| x = [[1, 2]] # x₀ |
| assert_eq([x for x in x for y in x], [[1, 2], [1, 2]]) |
| # x₁ x₁ x₀ x₁ |
| |
| # The scope of z (bound in loop 3) includes the operand of loop 2, |
| # permitting a forward reference. |
| assert_eq([1 // 0 for x in [] for y in z for z in ()], []) |
| |
| # Referring to it on the first iteration (before it is bound) is an error. |
| assert_fails( |
| lambda: [1 // 0 for x in [1] for y in z for z in ()], |
| "local variable 'z' is referenced before assignment", |
| ) |
| |
| # In this example there is a static forward reference |
| # and a dynamic loop-carried dependence. |
| assert_eq([y for x in (0, 1) for y in ([y] if x else [3])], [3, 3]) |
