Mon Oct 25

Let's pick up from where we were on Friday.

• Do exercise 3.6 : see attached 3-6.scm , and finish it. (Reviews "local persistent memory" from last time.)
• review "substitution model" ... see attached.
• Discuss make-decrementer from section 3.1.3 - consistent with substitution model, but no persistent memory
• Discuss make-simplified-withdraw ... trying (and failing) to get set! with substitution model.
• Discuss "sameness and change" ... what is equality?
• Discuss "pitfalls of imperative programming" ... do you agree? Similar example in python?
• Do exercise 3.8 : left-to-right vs right-to-left with different results.

Continue with material in section 3.2 : environment model of evaluation.

• In the author's vocabulary, what is an "environment"? a "frame?
• What data structures could you use for these?
• How do these ideas play out in other languages (e.g. python)?

Work through exercises 3.10 and 3.11 in class, depending on time. We'll continue next Monday if need be.

No class Thursday, and no assignment this week - study the text at least through section 3.2, and I'll see you on Monday.

We will be continuing into section 3.3 (Mutation); starting to read that stuff would be a good idea. I'll post an assignment due Thursday Nov 5 with exercises from sections 3.2 and 3.3.

attachments

		last modified	size
	3-6-in-class.scm	Mon Oct 25 2021 04:42 pm	3.7K
	3-6.scm	Sun Oct 24 2021 09:58 pm	2.7K
	subsitution.scm	Sun Oct 24 2021 09:58 pm	619B