PLQ #3Done on:   Tuesday, October 5th

Question 1 @ 2021-10-05 18:17

What is the best way to indent a With expression?

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• 1
  (With 'x (Num 2)
    (Add (Id 'x) (Num 4)))
• 2
  (With 'x
        (Num 2)
        (Add (Id 'x) (Num 4)))
• 3
  (With 'x (Num 2)
        (Add (Id 'x) (Num 4)))
• 4

  Any of these

• 5

  None of these

Question 2 @ 2021-10-05 18:19

What are the different kinds of identifiers that we discussed last week?

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• 1
  Lexical identifiers
• 2
  Dynamic identifiers
• 3
  Binding instances
• 4
  Bound occurrences
• 5
  Scoped identifiers
• 6
  Global identifiers
• 7
  Local identifiers

Question 3 @ 2021-10-05 18:21

What expressions are in the scope of the first y in this expression:

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• 0
  The question is bogus, we cannot distinguish just the first y.
• 1
  E1
• 2
  E2
• 3
  E3
• 4
  E4
• 5
  E5

Question 4 @ 2021-10-05 18:24

At some point we had the following broken bit of code in our implementation of subst:

Which of the following tests can be used to demonstrate the bug in this code fragment?

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• 1
  {with {x x} …}
• 2
  {with {x x} {with {x 3} …}}
• 3
  {with {x 3} {with {x x} …}}
• 4
  {with {x 3} {with {y x} …}}
• 5
  {with {y 3} {with {x y} …}}