learning-sicp

My embarrassing half assed SICP run.
git clone https://kaka.farm/~git/learning-sicp
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exercise-33.scm (2071B)

      1 (define-library (sicp solutions chapter-1 exercise-33)
      2   (import (scheme base))
      3   (import (only (sicp solutions chapter-1 exercise-21) prime?))
      4   (export
      5    iterative-filtered-accumulate
      6    iterative-sum-of-squares
      7    recursive-filtered-accumulate
      8    recursive-sum-of-squares
      9    )
     10 
     11   (begin
     12     (define (iterative-filtered-accumulate predicate? combiner null-value term a next b)
     13       (define (iter a result)
     14         (if (> a b)
     15             result
     16             (if (predicate? a)
     17                 (iter (next a)
     18                       (combiner (term a)
     19                                 result))
     20                 (iter (next a)
     21                       result))))
     22       (iter a null-value))
     23 
     24     (define (iterative-sum-of-squares a b)
     25       (iterative-filtered-accumulate prime?
     26                                      +
     27                                      0
     28                                      (lambda (x) (* x x))
     29                                      a
     30                                      (lambda (x) (+ 1 x))
     31                                      b))
     32 
     33     (define (recursive-filtered-accumulate predicate? combiner null-value term a next b)
     34       (if (> a b)
     35           null-value
     36           (let ([recur (recursive-filtered-accumulate predicate?
     37                                                       combiner
     38                                                       null-value
     39                                                       term
     40                                                       (next a)
     41                                                       next
     42                                                       b)])
     43             (if (predicate? a)
     44                 (combiner (term a) recur)
     45                 recur))))
     46 
     47     (define (recursive-sum-of-squares a b)
     48       (iterative-filtered-accumulate prime?
     49                                      +
     50                                      0
     51                                      (lambda (x) (* x x))
     52                                      a
     53                                      (lambda (x) (+ 1 x))
     54                                      b))))