Question 1 @ 2024-09-24 18:38

What’s your preference for when to do a remote class?

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• A

  The evening before the fall break (2024-11-27).

• B

  The last class of the semester, which is also the evening after the fall break (2024-12-03).

• C

  Both of the above.

• D

  Neither, I have some other date that is a better choice.

• E

  None, I’d like all classes in-person.

Question 2 @ 2024-09-24 18:40

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

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• A

  They’re a popular simple way of specifying grammars.

• B

  They’re easier to implement in a statically-typed language.

• C

  They’re inherently compositional so they simplify implementing evaluators.

• D

  They turned out to be useful representations, as seen by the history of S-expressions vs M-expressions in Lisp.

• E

  No real reason.

Question 3 @ 2024-09-24 18:41

For the following BNF, what is the simplest way to avoid ambiguity from the language implementor’s point of view?

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• A

  There is no ambiguity

• B

  Don’t do infix syntax, it’s always ambiguous

• C

  Change one of the <AE>s on each line to a <num> to enforce a direction

• D

  Add level(s) to enforce operator precedence

• E

  Add some required brackets around all options

• F

  Add some required brackets around all of the operator rules

Question 4 @ 2024-09-24 18:43

What is the problem with the following Typed Racket code?

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• A Broken define-type, since it refers to its own type
• B Missing contract comment
• C Missing type declaration
• D Redundant else clause
• E Bad type of the else clause