EBoard 28: Dictionaries (Section 1)

Warning! You are being recorded and transcribed, provided the technology is working correctly.

Approximate optimistic overview

• Administrative stuff
• Q&A
• Lab

Administrative stuff

Introductory notes

• Welcome to any Prospective Students. Please introduce yourself and (optionally) ask a question.
• Beware! Friday the 13th falls on Sunday.
• The graders have noted an increase in students using a style of defining procedures that I do not permit. It looks something like this. (define (proc param param param) body).
  • As I’ve noted before, if you define procedures without lambda, cut, composition, or aliasing, I won’t credit them. (In some cases, I will report you to CAS.)
  • So please use the correct form.
• Don’t forget to press the Register button before the end of the day!
  • Yes, there’s certainly room in 161.

Upcoming activities

Scholarly

• Tuesday, 15 April 2025, noon–1pm, Some PDR. CS Table: ???

Artistic

• Sunday, 13 April 2025, 2:00 p.m., Sebring-Lewis. Collegium Musicum
• Sunday, 13 April 2025, 2:00–3:00 p.m., Central Campus Stage. Kinetic Challenge

Multicultural

• Friday, 11 April 2025, 4:00–5:00 p.m., HSSC N1170 (Global Living Room). Middle of Everywhere: Sindhi community in Pakistan
• Saturday, 12 April 2025, 7:00–9:00 p.m., Harris Concert Hall. Cultural Evening

Artistic / Multicultural

• Saturday, 12 April 2025, 10:30–11:30 a.m., Drake Library. Superfest Disability Film Festival: Family-Friendly Shorts
• Saturday, 12 April 2025, 10:00 a.m.–noon, HSSC A2231. Superfest Disability Film Festival: Feature Film
• Saturday, 12 April 2025, 1:30 p.m.–3:45 p.m., HSSC A2231. Superfest Disability Film Festival: Chronic Pain Shorts
• Sunday, 12 April 2025, 10:00 a.m.–noon, HSSC A2231. Superfest Disability Film Festival: Feature Film
• Sunday, 12 April 2025, 1:30 p.m.–3:45 p.m., HSSC A2231. Superfest Disability Film Festival: Assorted Shorts and Panel

Peer

Musical, theatric, sporting, and academic events involving this section’s students are welcome.

• Read articles by your fellow CSC-151 students and comment on them online.
• Saturday, 12 April 2025, 10:00 a.m.–1:00 p.m. The Track and Field. Dick Young Invitational

Wellness

• Friday, 11 April 2025, 6:00–8:00 p.m., Aux Gym. Badminton Club (Smash that bird!)
• Friday, 11 April 2025, 6:30–8:00 p.m. Dance Studio. Brazilian Jiu-Jitsu
• Friday, 11 April 2025, 9:00 p.m., Noyce Elbow. Nerf at Noyce.
• Saturday, 12 April 2025, 4:00–6:00 p.m., Aux Gym. Badminton Club (Smash that bird!)
• Monday, 14 April 2025, 6:30–8:00 p.m. Dance Studio. Brazilian Jiu-Jitsu
• Tuesday, 15 April 2025, 5:00–6:00 p.m., HSSC Atrium. Therapy Dogs.
• Tuesday, 15 April 2025, 7:15–8:15 p.m., HSSC Atrium. Therapy Dogs.
• Tuesday, 15 April 2025, 12:00–12:45 p.m., Dance Studio. HIIT Training.
• Tuesday, 15 April 2025, 12:15–12:50 p.m., GCMoA. Yoga in the Museum.
• Tuesday, 15 April 2025, 4:30–6:30 p.m., BRAC P103 (Multipurpose Dance Studio). Wellness Yoga.
• Wednesday, 16 April 2025, 6:30–8:00 p.m., Dance Studio. Brazilian Jiu-Jitsu
• Thursday, 17 April 2025, 12:00–12:45 p.m., Dance Studio. HIIT Training.
• Thursday, 17 April 2025. ???. ???. Forest Bathing.

Misc

• Sunday, 13 April 2025, 7:30–8:30 p.m., Science 3819. Mentor Session: SoLA 3
• Tuesday, 15 April 2025, 7:00–8:00 p.m., Science 3820. Mentor Session: Dictionaries
• Wednesday, 9 April 2025, Noon–1:00 p.m., HSSC A2231 (Auditorium) Community Forum
  • “Weekly discussion on legal protections and recourse on issues that higher education and Grinnell College face.”
  • Also online.
  • This week (I think): Title VI, which prohibits discrimination based on race, color, national origin, or shared ancestry.

Other good things

These do not earn tokens, but are worth your consideration.

Upcoming work

• Sunday, 13 April 2025
  • Submit pre-reflection for SoLA 3 on Gradescope
  • Readings
    • Data abstraction
    • Submit reading response on Gradescope
  • Submit Friday’s lab on Gradescope
  • Submit late but not late MP7 on Gradescope
• Monday, 14 April 2025
  • Submit late but not late post-reflection for MP7 on Gradescope
  • SoLA 3 distributed
    • Topics from phase one: Decomposition, Primitive types, Collaboration, Lambda-free anonymous procedures (aka cut and compose).
    • Topics from phase two: Conditionals, Documentation, Testing, Lists (and “the big three”), Program Style, Ethical Considerations
    • Topics from phrase three you’ve done quizzes on: List recursion, local bindings.
    • New topics from phase three: Numeric recursion, vectors, randomness.
• Wednesday, 16 April 2025
  • Quiz: Dictionaries
  • Makeup quiz: Diagramming structures (paper only)
  • Makeup quiz: Tracing (paper only)
  • Don’t forget that you can bring a page of _hand written notes for each quiz._
• Thursday, 17 April 2025
  • SoLA 3 due
    • Topics from phase one: Decomposition, Primitive types, Collaboration, Lambda-free anonymous procedures (aka cut and compose).
    • Topics from phase two: Conditionals, Documentation, Testing, Lists (and “the big three”), Program Style, Ethical Considerations
    • Topics from phrase three you’ve done quizzes on: List recursion, local bindings.
    • New topics from phase three: Numeric recursion, vectors, randomness
• Sunday, 20 April 2025
  • Submit first redo for MP6 on Gradescope
  • Submit second redo for MP4 on Gradescope
  • Submit second redo for MP5 on Gradescope
• Sunday, 27 April 2025
  • Submit first redo for MP7 on Gradescope
• Friday, 16 May 2025
  • Submit final redo for MP1 on Gradescope
  • Submit final redo for MP2 on Gradescope
  • Submit final redo for MP3 on Gradescope
  • Submit final redo for MP4 on Gradescope
  • Submit final redo for MP5 on Gradescope

Friday PSA

Yes, I do this even though we have Prospective students here.

• Please stay awesome. People care about you.
• If you choose to do things that affect your body or brain chemistry, please do so in moderation.
• Consent is essential, but insufficient.

Questions

Administrative

Mini-project 7

Dictionaries etc.

Whoo! Almost no questions!

How is a hash table different from a list of pairs?

It provides more efficient access to elements (particularly when you have a lot of elements).

It lets us hide the underlying details. We think about the two or three key operations.

• Add an element (hash-set! hash key value).
• Look up an element (hash-ref hash key).

We talked some about the look up time of a list vs a vector. Does a hash have a look up time and method more similar to vectors or a list?

Mutable hash tables have lookup time similar to vectors.

Can you clarify what the common form means in terms of the new-hash procedures?

When we want similar things to be treated the same, we must explicitly convert them to a form in which they are extactly the same if we want to use hash tables.

Basically, ignoring case and non-letters (if I recall correctly).

Lab