Tuple Destructuring

[g-r-a-n-t]

What is wrong?

Users can't destructure tuples.

e.g.

(foo, bar): (u256, bool) = my_tuple

How can it be fixed

Implement destructuring in the lowering pass. The example statement above should be lowered to the following:

foo: u256 = my_tuple.item0
bar: bool = my_tuple.item1

edit: The above lowering would evaluate the expression twice, which is something we need to watch out for.

What we want is something like:

low_tuple: tuple_u256_bool = my_tuple
foo: u256 = low_tuple.item0
bar: bool = low_tuple.item1