Class 42: Evaluation and Wrapup

Held: Friday, May 12, 2006

Summary: Today we conclude the class.

Related Pages:

• EBoard.
• Some MidSem Code.

Overview:

• Grading.
• About the final.
• About the midsem.
• Wrapup.
• Evaluation forms.

Grading

About the final

• In class.
• Five moderately-short questions.
  • Four mostly correct: A
  • Three mostly correct: B
  • Two mostly correct: C
  • One mostly correct: D
  • Zero mostly correct: F
  • None attempted: 0
• Some likely topics (may be combined)
  • Prolog
  • Denotational Semantics
  • Haskell (laziness, pattern-based definitions, higher-order programming)
  • Polymorphism
  • FP
  • Ruby
  • SQL
  • Types
  • Future of languages

About the Midsem

• A mixed bag. Some excellent scores. Some mediocre.
• Revised numeric grading scheme to the grading scheme mentioned above.
• Problem one:
  • Key issue: Expressions may change the environment
  • Therefore: When we evaluate an expression, we need to 'return' both a value and a new environment
  • One strategy: Return a pair
  • Another: Take a continuation as a parameter
  • Second key issue: All the operations must be rewritten with this syntax
  • Third key issue: Particularly the binary functions on expressions
• Problem two:

  (define cached 0)
  (define suspend
    (lambda ()
      ; Grab the current continuation
      (let/cc k
        ; Grab the cached continuation
        (let ((resume cached))
          ; Cache the current continuation
          (set! cached k)
          ; Resume or stop
          (if (not (eq? cached 0)) (resume))))))
  
  (define reset
    (lambda ()
      (set! cached 0)))
  

Wrapup

• Designed as a different kind of CS course
• Intended morals of the course:
  • You can read the primary literature (and it may be worth doing so)
  • Different languages/paradigms help you think differently
  • Understanding CS requires understanding Math
  • Take everything with a grain of salt
  • Grading is less important than doing
• I've enjoyed teaching this course. I hope you've enjoyed learning from it.

Evaluation forms

• Fill it out.
• Deliver it to the science office.
• Leave.
• Study hard this weekend.