Outline:

1. Types
   • what is a type?
   • what can we do with types?
   • type checking
2. Garbage collection
   • exercise: brainstorm a garbage collector for your interpreter
3. Wrap-up

What’s next

Upcoming events/assessments:

• Last CS Bits and Bytes Thursday at 3:30pm in Anderson 329
• Interpreter Part 5 cannot be resubmitted after tomorrow at 10pm
• In-class work day on Friday – attendance counts towards engagement credits (WEIRD SCHEDULE)
• Quiz 7 (our last in-class quiz) will be next Monday and cover the following Quiz Learning Objectives:
  • Advanced:
    • PL 8: types
    • IP 9: evaluation order
    • IP 10: primitives
  • Repeat:
    • Core:
      • PL 3: compilers vs. interpreters
      • PL 4: Backus-Naur form
      • PL 6: scoping
      • FS 5: higher-order functions
      • FS 6: currying and partial application
      • FS 7: lazy lists
      • FS 8: reading Scheme
      • IC 2: stack vs. heap
      • IC 3: structs
      • IC 5: strings
      • IC 6: reading C
      • IP 1: linked list
      • IP 2: memory management
      • IP 3: tokenization
      • IP 4: parsing
      • IP 5: evaluating simple expressions
    • Advanced:
      • FS 11: tail recursion
      • FS 13: set! vs. define
      • IP 7: evaluating procedures
      • IP 8: handling quote

What you should do now:

• Read the assigned readings (see below)
• Finish P5 and P6
• Work on P7: Primitives

Reading assignment (to be completed by the next class):

From today:

• Type systems
• Garbage collection – this is about C++, but mentally just replace new/delete with malloc/free as you read it

For next time:

• None, just work on your interpreter this Friday and prep for Quiz 7 on Monday!