PLQ #5Done on: Tuesday, October 19th

Question 1 @ 2021-10-19 18:12

In a dynamically-scoped version of Flang, what would the following evaluate to?

{with {f {fun {x} {call f x}}}
{call f 0}}

0
0
1
Unbound identifier error.
2
Infinite loop.
3
Stack overflow / out of memory.
4
Error on bad with syntax.
5
We don’t have with in the dynamically-scoped variant of the language.

Question 2 @ 2021-10-19 18:15

What are the advantages of dynamic scope?

1
Predictable execution that we can reason about.
2
Modeling the real world.
3
Free recursive calls without further implementation.
4
Being able to “reach in” and customize all values and behaviors.
5
Simple to compile.
6
Efficient execution.

Question 3 @ 2021-10-19 18:17

What are the disadvantages of dynamic scope?

1
Unpredictable execution that we cannot reason about.
2
Natural scoping rules.
3
No recursive calls without further implementation.
4
Impossible to compile.
5
Inefficient execution.

Question 4 @ 2021-10-19 18:19

What do we get if we run the following code:

(define (foobar)
(+ x y z))

(define (fun z)
(foobar))

(let* ([x 2] [y 4]) ; same as two nested `let`s
(fun 3))

(Choose the best answer.)

1
We get a result of 9.
2
We get a result of 6 if the language has dynamic scope.
3
We get a result of 9 if the language has lexical scope.
4
We get an error if the language has lexical scope.
5
We get an error if the language has dynamic scope.