Symbolic Processing in Scheme II: class notes
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(define (dec->bin x L)
(if (= x 0) L
(if (odd? x)
(dec->bin (/ x 2) (cons 1 L))
(dec->bin (/ x 2) (cons 0 L)))))
(dec->bin 26 '())
->(dec->bin 13 '(0))
->(dec->bin 6 '(1 0))
->(dec->bin 3 '(0 1 0))
->(dec->bin 1 '(1 0 1 0))
->(dec->bin 0 '(1 1 0 1 0))
-> '(1 1 0 1 0)
(define (bin->dec L x)
(if (null? L) x
(bin->dec (rest L) (+ (first L) (* 2 x)))))
(bin->dec '(1 0 0 1 0) 0)
->(bin->dec '(0 0 1 0) (+ 1 (* 2 0)))
->(bin->dec '(0 0 1 0) 1)
->(bin->dec '(0 1 0) (+ 0 (* 2 1)))
->(bin->dec '(0 1 0) 2)
->(bin->dec '(1 0) (+ 0 (* 2 2)))
->(bin->dec '(1 0) 4)
->(bin->dec '(0) (+ 1 (* 2 4)))
->(bin->dec '(0) 9)
->(bin->dec '() (+ 0 (* 2 9)))
->(bin->dec '() 18)
-> 18
(define (sq x) (* x x))
-> (map sq '(1 2 3 4 5))
-> '((sq 1) (sq 2) (sq 3) (sq 4) (sq 5))
-> '(1 4 9 16 25)
-> (apply + '(1 2 3 4 5))
-> (+ 1 2 3 4 5)
-> 15
-> (apply + (map sq '(1 2 3 4 5)))
-> (apply + '(1 4 9 16 25))
-> 55
(define (li x)
(string-append "<li>" x "</li>"))
(define (ul x)
(string-append
"<ul>"
(apply string-append (map li x))
"</ul>"))
(ul '("a" "b" "c"))
->(string-append "<ul>" (apply string-append (map li '("a" "b" "c"))) "</ul>")
->(string-append "<ul>" (apply string-append (list (li "a") (li "b") (li "c"))) "</ul>")
->(string-append "<ul>" (apply string-append (list "<li>a</li>" "<li>b</li>" "<li>c</li>"))) "</ul>")
->(string-append "<ul>" "<li>a</li><li>b</li><li>c</li>" "</ul>")
->"<ul><li>a</li><li>b</li><li>c</li></ul>"
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