lect02a


IV: practice: blend3 (having a function call a function)
  Include trivial test-cases first (if it doesn't pass, easy to debug)

V: practice: area-of-disk; area-of-ring
a(r) = pi*r^2     area-of-disk
area-of-ring(r2,r1)

   Use check-within

VIa: types in scheme:
  number (integer, rational, inexact, complex; 
     functions +, /; 
     number?, integer?, exact?, rational?; zero? positive?, 
     number->string, inexact->exact );
  string (string-append, string=?, string?)
  boolean  (boolean=?, not, and, or)
  symbols; only functions are symbol? and symbol=?; symbol->string
     Used like enums, or to emphasize it's a tag that you'll
     never do string-work on.
  images (!)  Use menu item 'scheme > insert image'

VIb: images, image-primitives
   circle, rectangle
   overlay/xy, image-width, image-height

VII: write image-functions
  (define (align-h img1 img2)
    (overlay/xy img1 (image-width img1) 0 img2))
Write align-v
board2x2
board4x4
board8x8
  




------------
Possibly to mention in future: 
btw, compare these function calls to the sh:
                      find . -name \*.ps -print
                      find . -name \*.ps -print | grep -i wimpout
Note that args can be passed by position (first arg to 'find'),
  or by name (the '-name' flag, in this case)
  What about '-i wimpout'?  What drawbacks to differenting a real filename
  from flags starting with '-'?  
Try:
cat > -i
hello
^D

grep hel -i
grep -- hel -i

What about a program, where the filname is in a variable?




Back to scheme:
let x = 3.

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