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-rw-r--r--net/ricketyspace/sicp/one/twentyseven.scm20
1 files changed, 8 insertions, 12 deletions
diff --git a/net/ricketyspace/sicp/one/twentyseven.scm b/net/ricketyspace/sicp/one/twentyseven.scm
index 891432f..cc50dc9 100644
--- a/net/ricketyspace/sicp/one/twentyseven.scm
+++ b/net/ricketyspace/sicp/one/twentyseven.scm
@@ -4,7 +4,7 @@
(define-module (net ricketyspace sicp one twentyseven)
#:use-module (srfi srfi-1)
- #:export (carmichael-numers-fool-fermat-test?))
+ #:export (carmichael-numbers-fool-fermat-test?))
(define carmichael-numbers '(561 1105 1729 2465 2821 6601))
@@ -20,18 +20,14 @@
m))))
(define (fermat-test n)
- (define (try-it a)
+ (define (pass? a)
(= (expmod a n n) a))
- (try-it (+ 1 (random (- n 1)))))
+ (fold (lambda (a p) (and (pass? a) p)) #t (iota (1- n) 1)))
-(define (fast-prime? n times)
- (cond ((= times 0) #t)
- ((fermat-test n) (fast-prime? n (- times 1)))
- (else #f)))
+(define (prime? n)
+ (if (fermat-test n) #t #f))
-(define (carmichael-numers-fool-fermat-test?)
+(define (carmichael-numbers-fool-fermat-test?)
"Returns #t if all `carmichael-numbers` pass (fool) the fermat test."
- (let* ((fooled-test? (lambda (n) (fast-prime? n 100000)))
- (fooled? (lambda (result) (eq? result #t)))
- (results (map fooled-test? carmichael-numbers)))
- (every fooled? results)))
+ (define (fooled-test? n) (prime? n))
+ (fold (lambda (n p) (and (fooled-test? n) p)) #t carmichael-numbers))