PLQ #4Done on:   Tuesday, October 12th

Question 1 @ 2021-10-12 18:07

Which kinds of functions do we have in our current version of the Flang language?

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• 1
  First-order functions.
• 2
  First-class functions.
• 3
  Higher-order functions.
• 4
  Higher-class functions.
• 5
  None of the above, since our support for functions is premature.

Question 2 @ 2021-10-12 18:09

Say that we use de-Bruijn indexes similar to what we’ve seen in class. What would be the result of evaluating the following?

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• 1
  The expression is nonsensical, eg, it lacks a function argument name.
• 2
  The result would be 6.
• 3
  The result would be a function, which will cause a runtime error when called.
• 4
  The result is a function that returns its input plus 1.
• 5
  The result is a function that returns its input plus 5.

Question 3 @ 2021-10-12 18:11

What is the main problem with our current Flang language implementation?

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• 1
  Our bindings are not handled correctly yet.
• 2
  Function calls are slow, so we need to change the interpreter-based implementation into a compiler using de-Bruijn indexes.
• 3
  Function calls are slow, corresponding to the function sizes.
• 4
  We’re missing a way to build object values.

Question 4 @ 2021-10-12 18:13

We can drop the with from Flang because we can replace any use:

with

Is this symmetric? — Could we similarly drop the call+fun and manage with just with?

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• 1
  Of course not, we can express more ideas since we broke with into two independent features.
• 2
  Of course we can, we just need to do a similar substitution as above, but in reverse.
• 3
  The question is nonsensical, because we cannot always replace with using call + fun.
• 4
  Of course not, since any kind of such substitution loses the original code and therefore the intended meaning that the programmer had.