PLQ #2

Question 1 @ 2024-01-23 18:17

Did you know that you can suggest PLQ questions?

A
What’s a “PLQ”?
B
I had no idea.
C
Wait, that was serious?? I thought it was a joke.
D
I know that, but hookairs.
E
I know that, but I don’t want to.
F
I know that, but I’m afraid to write bad questions.
G
I know that, and plan to do so in the future.
H
(Or write anything, if none of the above.)

Question 2 @ 2024-01-23 18:19

Which of the following BNF grammars are ambiguous?

(Multiple choice!)

A
<AE> = <num> | <AE> + <AE> | <AE> * <AE>
B
<AE> = <num> | ( <AE> + <AE> ) | ( <AE> * <AE> )
C
<AE> = <MUL> + <MUL>
<MUL> = <num> | <num> * <MUL>
D
<AE> = <num> | <ADD> | <MUL>
<ADD> = <AE> + <AE>
<MUL> = <AE> * <AE>

Question 3 @ 2024-01-23 18:23

What is the reason we’re choosing BNFs to specify our language(s)?

A
They’re a commonly known simple way of specifying grammars.
B
They’re easier to implement compilers for.
C
They’re easier to implement interpreters for.
D
They make it easy to avoid non-deterministic syntax.
E
They turned out to be useful representations, as seen by the history of S-expressions in Lisp.
F
No reason.

Question 4 @ 2024-01-23 18:26

Generally speaking, what did we mean by the term “compositional”?

A
Making frequent use of function composition, meaning a heavy focus on functional programming.
B
The meaning of something depends only on the meaning of its sub-parts and nothing else.
C
Sticking to a modular implementation of languages, so we can easily change various parts of the code.
D
Same as using “combinatorial”, which cannot be used since it’s often associated with discrete math.
E
Nothing special.

Question 5 @ 2024-01-23 18:27

Tail-call elimination optimizes code in which of the following ways?

(Reminder: choose the best answer!)

A
Improves the semantics by making it simpler
B
Improves time complexity (runtime)
C
Improves space complexity (space)
D
Improves style by being more idiomatic Racket
E
Allows compiling recursive loops into efficient machine code