learning-sicp

My embarrassing half assed SICP run.
git clone https://kaka.farm/~git/learning-sicp
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exercise-17.scm (562B)

      1 (define-library (sicp solutions chapter-1 exercise-17)
      2   (import (scheme base))
      3   (export *-recursive
      4           fast-*-recursive)
      5 
      6   (begin
      7     (define (*-recursive a b)
      8       (if (= b 0)
      9           0
     10           (+ a (*-recursive a (- b 1)))))
     11 
     12     (define (double n)
     13       (* 2 n))
     14 
     15     (define (halve n)
     16       (/ n 2))
     17 
     18     (define (fast-*-recursive a b)
     19       (cond
     20        ((= b 0) 0)
     21        ((even? b) (+ (double a)
     22                      (fast-*-recursive a
     23                                        (- b 2))))
     24        (else (+ a (fast-*-recursive a (- b 1))))))))