From: Ramakrishnan Muthukrishnan Date: Sun, 6 Jan 2013 17:01:00 +0000 (+0530) Subject: solution to 4.43 X-Git-Url: https://git.rkrishnan.org/simplejson/components/com_hotproperty//%22%3C?a=commitdiff_plain;h=faf2878f765ff8f97c43f1f090709d12b3e2c11e;p=sicp.git solution to 4.43 --- diff --git a/src/sicp/ex4_43.rkt b/src/sicp/ex4_43.rkt new file mode 100644 index 0000000..0cbe9e6 --- /dev/null +++ b/src/sicp/ex4_43.rkt @@ -0,0 +1,53 @@ +#lang racket + +(require "amb-eli.rkt") +(require "distinct.rkt") + +#| + +Fathers: + +1. Moore - yatch - lorna +2. Colonel Downing - melissa +3. Mr. Hall - rosalind +4. Sir Barnacle Hood (Melissa's father) - gabreille +5. Dr. Parker - mary ann moore + +Daughters + +1. Mary Ann Moore +2. Gabrielle +3. Lorna +4. Rosalind +5. Melissa's father is Sir Barnacle Hood + +|# + +(define (get-yatch father) + (case (string->symbol (string-append (symbol->string father) "-y")) + [(moore-y) 'lorna] + [(downing-y) 'melissa] + [(hall-y) 'rosa] + [(barnacle-y) 'gab] + [(parker-y) 'mary])) + +(define (father x) (first x)) +(define (daughter x) (second x)) +(define (yat x) (third x)) + +(define (yatch) + (let ([moore (list (amb 'mary) 'lorna)] + [downing (list 'downing (amb 'gab 'lorna 'rosa) 'melissa)] + [hall (list 'hall (amb 'gab 'lorna) 'rosa)] + [barnacle (list 'barnacle (amb 'melissa) 'gab)] + [parker (list 'parker (amb 'gab 'lorna 'rosa) 'mary)]) + (let ([gab-father (amb hall downing parker)] + [lorna-father (amb hall downing parker)]) + (assert (eq? (daughter gab-father) 'gab)) + (assert (eq? (daughter lorna-father) 'lorna)) + (assert (eq? (yat gab-father) (daughter parker))) + (assert (not (eq? (daughter lorna-father) (yat lorna-father)))) + (assert (not (eq? (daughter gab-father) (yat gab-father)))) + lorna-father))) + +(yatch)