---
title: Eboard 33  Association lists
number: 33
section: eboards
held: 2017-11-15
---
CSC 151.01, Class 33:  Association lists
========================================

_Overview_

* Preliminaries
    * Notes and news
    * Upcoming work
    * Extra credit
    * Questions
    * Mentor evaluations
* Lab
* Debrief

### News / Etc.

### Upcoming Work

* No reading for Friday.  Work on your projects.
* [Writeup for class 32](../writeups/writeup32) due TODAY at 10:30 p.m.
    * Exercise 6
    * To: <csc151-01-grader@grinnell.edu>
    * Subject: CSC 151.01 Writeup 32 (YOUR NAMES)
* [Writeup for class 33](../writeups/writeup33) due Friday at 10:30 p.m.
    * Exercise 4b and 4c.
    * To: <csc151-01-grader@grinnell.edu>
    * Subject: CSC 151.01 Writeup 33 (YOUR NAMES)
* Exam 3 cover pages due NOW!
    * Fringies are a sign of disrespect.
* Exam 3 Epilogues due TONIGHT!

### Extra credit (Academic/Artistic)

* Convocation Thursday at 11 a.m. in JRC 101.  "Work's Provocative Future: 
  Which Graduates Will Thrive?"

### Extra credit (Peer)

* Pub-free quiz at Bob's.  9pm (I think).  Math-Stats focus.
* "The First Time I Walked on the Moon".  Four, count 'em, four performances.
  Thursday at 7:30, Friday at 7:30, Saturday at 7:30, Sunday at 2:00.
* Orchestra, Saturday at 2pm

### Extra credit (Misc)

### Other good things

* Fresh Flutes Thursday
* Voice recitals Friday at 4:15 (Henderson) and 7:00 (Manuel)
* Women's Basketball vs. Emmaus TONIGHT at 5:00 p.m.
* Men's Basketball vs. Emmaus TONIGHT at 7:00 p.m.
* Swimming and Diving Saturday at 1:00 p.m.

### Questions

### Mentor Evaluations

* Think about them as a group.
* Our goal is to improve the program.
* Aren't forms fun?

Lab
---

Writeup: 4b and 4c.

When you write `multi-assoc` (or `assoc-all` or `multi-assoc-2nd`),
think about the base case.  You are returning a list of matching elements.  
Hence, if there are no matches, you should return ...?

```
> (multi-assoc "Sky Rebel" cartoon-sidekicks)
'()
```

How do you pronounce "assoc"?
  : Sometimes I say "a sock", with a short o
  : Sometimes I say "a sosh", with a long o (or like the "soc" in "sociology")
  : But I also pronounce "ghoti" as "fish"

More Announcements
------------------

_Whoops.  Forgot these._

* Reminder: Tomorrow's convo looks to be cool.  You should go.
* Looking ahead: Angela Willig is running what looks to be a really 
  awesome role playing scenario the Tuesday after Turkey break.
* Quiz Friday: Algorithm analysis, association lists, maybe more trees
* Review sessions: Tonight at 8pm, Tomorrow at 7pm and 8pm.

Debrief
-------

How many of you wrote `assoc-all` (`multi-assoc`).

```
(define assoc-all
  (lambda (lst val)
    (let kernel ([so-far null]
                 [remaining lst])
      (cond
        [(null? remaining)
         (reverse so-far)]
        [(equal? val (caar remaining))
         (kernel (cons (car remaining) so-far)
                 (cdr remaining))]
        [else
         (kernel so-far
                 (cdr remaining))]))))
```

How I would have written `assoc-all`.

```
(define assoc-all
  (lambda (lst val)
    (cond
      [(null? lst)
       null]
      [(equal? val (caar lst))
       (cons (car lst) (assoc-all (cdr lst)))]
      [else
       (assoc-all (cdr lst))])))
```