(define (make-sum a b . rest) (letrec ((make-sum-sub (lambda (terms sum) (cond [(zero? sum) (cond [(null? terms) 0] [(null? (cdr terms)) (car terms)] [else (cons '+ terms)])] [(null? terms) sum] [else (cons '+ (cons sum terms))])))) (let (…

(use gl) (use gl.glut) (define (display) (gl-clear GL_COLOR_BUFFER_BIT) (gl-begin GL_LINES) (gl-color 1.0 0.0 0.0) ((square-limit painter-wave 5) (make-frame (make-vect -1.0 -1.0) (make-vect 2.0 0.0) (make-vect 0.0 2.0))) (gl-end) (gl-flus…

;; 2.42 (define (queens board-size) (letrec ((queen-cols (lambda (k) (if (= k 0) (list empty-board) (filter (lambda (positions) (safe? k positions)) (flatmap (lambda (rest-of-queens) (map (lambda (new-row) (adjoin-position new-row k rest-o…

;; 2.29 (define (make-mobile left right) (list left right)) (define (make-branch length structure) (list length structure)) ;; a (define left-branch car) (define right-branch cadr) (define branch-length car) (define branch-structure cadr) …