CSC151 2009F, Class 43: Higher-Order Procedures, Revisited

Admin:
* Reading for Wednesday: Searching.
* I'll reserve some time at the start of class for questions and 
  comments on the project proposals.
* EC for ...
  * Attending the swim meet on Friday.
* Once again, I'm trying for no lecture (beyond the stuff above); 
  only Q&A prior to lab.

Overview:
* Followup on Campus Climate Survey
* Project proposals
* Questions about the reading?

Followup on Campus Climate Survey
* Comment from student: Should have told us to do "the reading" in advance.
* Comment from student: Noted that Grinnell is doing better than some 
  institutions, where "only 2% of people experience harassment".
  * I'm not sure why that's better.
  * I do know that it's better that the majority of Grinnellians are at
    least aware that harassment occurs, since it's a starting point.
* Comment from student: Groups at Grinnell are very insular.  Does that
  contribute to the problem?  Is that something we can change?

Project Proposals
* An unacceptable proposal:
  "We plan to utilize all the techniques we have learned to create images that explore uses of colors and shapes. The images we create will span a wide variety of image types and artistic aesthetics.  We will utilize everything from shapes on a white background to complex multicolored color blends."

* Reusing existing images:
;;; Procedure:
;;;   image-copy-and-paste!
;;; Parameters:
;;;   source, an image
;;;   target, an image
;;; Purpose:
;;;   Copies the selected region of source and pastes it into
;;;   the selected region of target
;;; Produces:
;;;   [Nothing; called for the side effect]
;;; Preconditions:
;;;   Both images are valid.
;;;   Both images have selected regions.
;;;   The source and target regions are the same size (may not
;;;     be necessary).
;;; Postconditions:
;;;   The selected region of target now contains the same
;;;     stuff as the selected region of source.
;;;   Nothing is selected in target.
(define image-copy-and-paste!
 (lambda (source target)
  (gimp-edit-copy (image-get-layer source))
  (gimp-edit-paste (image-get-layer target) FALSE)
  (gimp-image-flatten target)))

* General note: Almost everything described in the Procedure Browser is
  available.
  * Some of the procedures refer to a 'drawable'
    * 'drawables' are layers and other similar things.  
    * You can access the current 'drawable' on an image with
      (image-get-layer IMAGE)

* Questions
  * Can I use a big cond?
    * Yes
  * Can I PLEAASE make it representational
    * Sure.  However, experience suggests that the non-represntational
      ones are generally more interesting
  * Can I reuse code from a homework
    * Yes.
  * What if we can't reach our aspirations?
    * We'll be sad
    * You'll revise your statement
  * What percent of our grade will be determined by Prof. Kluber?
    * None
    * You just experience public praise or humiliation (or both)

LAB!

(define dot-product
  (lambda (lst1 lst2)
    (apply + (map * lst1 lst2))))