Homework 3

Language: Beginning Student with List Abbreviations

1 Family Trees

; A ftn is either

; - 'unknown

; - (make-child symbol number symbol ftn ftn)

(define-struct child (name date eyes mom dad))

Write the following functions:

; proper-blue-eyed-ancestor : ftn -> boolean

; returns true if ‘f’ has a blue-eyed ancestor,

; but where a person does not count as their own ancestor

; (This is exercise 14.1.6 from HtDP.)

(define (proper-blue-eyed-ancestor f) ---)

; eye-colors : ftn -> (listof symbol)

; returns a list of all of the eye-colors in ‘f’

; (if there are multiple ancestors with the same eye-colors,

; the list should contain multiple occurrences of the same symbol)

(define (eye-colors f) ---)

; no-dup-eye-colors : ftn -> (listof symbol)

; returns a list of all of the eye-colors in ‘f’

; this list should contain at most one occurrence of

; each different eye-color

(define (no-dup-eye-colors f) ---)

2 Lists of people

; A person is

; - (make-person symbol number symbol)

(define-struct person (name date eyes))

; A list-of-person is either

; - empty

; - (cons person list-of-person)

Write the following function:

; linearize : ftn -> list-of-person

; returns a list of the people in ‘f’ such that

; the earlier elements in the list are all younger

; than the later ones