Summary CPSC 110 PSET 8 SOLUTION

;; The first three lines of this file were inserted by DrRacket. They record
metadata
;; about the language level of this file in a form that our tools can easily
process.
#reader(lib "htdp-intermediate-reader.ss" "lang")((modname pset-08-solution) (read-
case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-
decimal #f #t none #f () #t)))
;; DO NOT PUT ANYTHING PERSONALLY IDENTIFYING BEYOND YOUR CWL IN THIS FILE.
;; YOUR CWLs WILL BE SUFFICIENT TO IDENTIFY YOU AND, IF YOU HAVE ONE, YOUR
;; PARTNER.
;;
(require spd/tags)

(@assignment pset-08); Do not edit or remove this tag


(@problem 1)
;;
;; Design a function called sum-squares that consumes a list of naturals,
;; and produces the sum of squaring all of the naturals in the list.
;;
;; For example: (sum-squares (list 5 2 4)) produces 45.
;;
;; Your function definition must use built-in abstract functions.
;; For full marks it must be a composition of exactly 2 built-in
;; abstract functions.
;;

(@htdf sum-squares)
(@signature (listof Natural) -> Natural)
;; produce the sum of squaring all of the numbers in lon
(check-expect (sum-squares empty) 0)
(check-expect (sum-squares (list 5 2 4))
(+ (sqr 5) (sqr 2) (sqr 4)))

(@template fn-composition use-abstract-fn)

(define (sum-squares lon)
(foldr + 0 (map sqr lon)))


(@problem 2)
;;
;; Complete the design of the following function.
;;
;; Your function definition must use built-in abstract functions.
;; For full marks it must be a composition of exactly 2 built-in
;; abstract functions.
;;
;; NOTE: Looking up the function string-contains? in the help desk
;; might be helpful...

(@htdf all-a-contain?)
(@signature (listof String) String -> Boolean)
;; determine if all strings that begin with the letter 'a' contain word w
(check-expect (all-a-contain? empty "word") true)
(check-expect (all-a-contain? (list "bicycle" "car" "train" "walk")
"transportation")
true)

, (check-expect (all-a-contain? (list "assignment") "eight") false)
(check-expect (all-a-contain? (list "attend" "radio" "antenna" "listen" "study")
"ten")
true)
(check-expect (all-a-contain? (list "art" "bin" "action" "tin") "in") false)
(check-expect (all-a-contain? (list "art" "artery" "ban" "action" "tin")
"art")
false)

(@template fn-composition use-abstract-fn)

(define (all-a-contain? los w)
(local [(define (contains-word? s)
(string-contains? w s))
(define (starts-with-a? s)
(string=? "a" (string-ith s 0)))]
(andmap contains-word? (filter starts-with-a? los))))


;;
;; Before completing problems 3, 4, and 5, please familiarize
;; yourself with the provided data definition for a Cat.
;; An example (listof Cat) is also provided.
;;

(@htdd Cat)
(define-struct cat (name color age))
;; Cat is (make-cat String Color Natural)
;; interp. a cat with a name, coat color, and age (in years)
(define C1 (make-cat "Whiskers" "brown" 13))
(define C2 (make-cat "Si" "black" 4))
(define C3 (make-cat "Am" "white" 4))
(define C4 (make-cat "Meow" "brown" 7))
(define C5 (make-cat "Garfield" "orange" 8))
(define C6 (make-cat "Sassy" "brown" 6))

(define (fn-for-cat c)
(... (cat-name c)
(cat-color c)
(cat-age c)))

(define LOC1 (list C1 C2 C3 C4 C5 C6)) ; to save time with check-expects


(@problem 3)
;;
;; Design a function called brown-cat-names that consumes a list of cats,
;; and produces a list of the names of the cats that are brown in color.
;;
;; For example: (brown-cat-names LOC1)
;; produces: (list "Whiskers" "Meow" "Sassy")
;;
;; Your function definition must use built-in abstract functions.
;; For full marks it must be a composition of exactly 2 built-in
;; abstract functions.
;;

(@htdf brown-cat-names)
(@signature (listof Cat) -> (listof String))