;; "relate" accepts a positive integer x and relation R and returns { y | (x y) €R }. ;; Type signature: (relate positive-int relation) -> set-of-ints (define (relate x R) (define (relate-helper x R) (cond [(null? R) '0] [(= x (caar R)) (cons (cadar R) (relate-helper x (cdr R)))] [else (relate-helper x (cdr R))])) (make-set (relate-helper x R)))
;; "relate" accepts a positive integer x and relation R and returns { y | (x y) €R }. ;; Type signature: (relate positive-int relation) -> set-of-ints (define (relate x R) (define (relate-helper x R) (cond [(null? R) '0] [(= x (caar R)) (cons (cadar R) (relate-helper x (cdr R)))] [else (relate-helper x (cdr R))])) (make-set (relate-helper x R)))
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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The question is the first screenshot, and in the second I have attached the "relate" helper function. I keep trying and feel I am overcomplicating things majorly and was wondering if there's a simpler way to complete this.
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