#lang racket ; Returns the length of a list. (define (list-length xs) ; Returns the sum of a a list of numbers. (define (sum xs) ; Returns a list with consecutive integers in order from lo to hi. (define (range lo hi) ; Returns a list where each element is the square ; of the corresponding element in xs. (define (squares xs) ; Returns a list containing only even numbers in xs, in order. (define (evens xs) ; Returns #t if the list ys contains element x and #f otherwise. (define (contains? x ys) ; Returns a new list containing all the elements of ys, in order, ; except x. (define (remove x ys) ; Returns #t if the list is in sorted order and #f otherwise. (define (sorted? xs) ; Returns a list containing all of the elements of xs, but ; with no duplicates. (define (dedup xs)