Hello Everyone,                 i a a newbie who is trying to find his way through the "jungle of programming" by using the HTDP map. This time in sectio-6 i ran into a problem in understanding the "crucial ways" the map represents. I have solved the "pre-hangman problems" (i.e. ex 6.7.1 - .2 & .3) . both programes execute without any error, but when i try to play "hangman" game using both of them i get an error: ------------------------- ERROR: The teachpack file /usr/lib/plt/teachpack/htdp/hangman.ss did not load properly. teachpack: export of stop from "/usr/lib/plt/teachpack/htdp/hangman.ss" conflicts with already existing definitions ------------------------------------ I have drscheme version209 running on debian "sarge". may you help me? ;; -------------here is the programme----------- (define-struct word (s1 s2 s3)) ;;a word is a structure: (make-word s s s), where s s & s are symbols. #| ;; reveal : word word letter -> 3l-word ;; to produce a word dependent on & from given 3 different arguments ;; (define (reveal chosen-word status-word letter-guessed)..) ;; examples (reveal (make-word 't'e'a) (make-word '_'e'_) 'u) ;; expected value (make-word '_'e'_) (reveal (make-word 't'e'a) (make-word 't'_'_) 'a) ;; expected value (make-word 't_'a) (reveal (make-word 'a'l'l) (make-word '_'_'_) 'l) ;; expected value (make-word '_'l'l)  TEMPLATE: (define (process-reveal word1 word2 letter)   ...(word-s1 word1)...(word-s1 word2)...   ...(word-s2 word1)...(word-s2 word2)...   ...(word-s3 word1)...(word-s3 word2)...) |# (define (reveal word-chosen word-status a-letter)   (cond     [(test-all3 word-chosen word-status a-letter) (create-full word-chosen word-status a-letter)]     [(test-12 word-chosen word-status a-letter) (create-12 word-chosen word-status a-letter)]     [(test-23 word-chosen word-status a-letter) (create-23 word-chosen word-status a-letter)]     [(test-13 word-chosen word-status a-letter) (create-13 word-chosen word-status a-letter)]     [(symbol=? (word-s1 word-chosen) a-letter) (create-word-s1 word-chosen word-status a-letter)]     [(symbol=? (word-s2 word-chosen) a-letter) (create-word-s2 word-chosen word-status a-letter)]     [(symbol=? (word-s3 word-chosen) a-letter) (create-word-s3 word-chosen word-status a-letter)]     [else word-status])) (define (test-all3 word1 word2 a-letter)   (and (symbol=? (word-s1 word1) a-letter)        (symbol=? (word-s2 word1) a-letter)        (symbol=? (word-s3 word1) a-letter))) (define (create-full word1 word2 a-letter)   (make-word a-letter              a-letter              a-letter))   (define (test-12 word1 word2 a-letter)   (and (symbol=? (word-s1 word1) a-letter)        (symbol=? (word-s2 word1) a-letter))) (define (test-23 word1 word2 a-letter)   (and (symbol=? (word-s3 word1) a-letter)        (symbol=? (word-s2 word1) a-letter))) (define (test-13 word1 word2 a-letter)   (and (symbol=? (word-s1 word1) a-letter)        (symbol=? (word-s3 word1) a-letter))) (define (create-12 word-chosen word-status a-letter)   (make-word a-letter              a-letter              (word-s3 word-status))) (define (create-23 word-chosen word-status a-letter)   (make-word (word-s1 word-status)              a-letter              a-letter)) (define (create-13 word-chosen word-status a-letter)   (make-word a-letter              (word-s2 word-status)              a-letter)) (define (create-word-s1 word-chosen word-status a-letter)   (make-word a-letter              (word-s2 word-status)              (word-s3 word-status))) (define (create-word-s2 word-chosen word-status a-letter)   (make-word (word-s1 word-status)              a-letter              (word-s3 word-status))) (define (create-word-s3 word-chosen word-status a-letter)   (make-word (word-s1 word-status)              (word-s2 word-status)              a-letter)) #| ;; tests (reveal (make-word 't'e'a) (make-word '_'e'_) 'u) ;; expected value = (make-word '_'e'_) (reveal (make-word 't'e'a) (make-word 't'_'_) 'a) ;; expected value = (make-word 't'_'a) (reveal (make-word 'a'l'l) (make-word '_'_'_) 'l) ;; expected value = (make-word '_'l'l) (reveal (make-word 'l'l'l) (make-word '_'_'_) 'l) ;; expected value = (make-word 'l'l'l) (reveal (make-word 'a'l'l) (make-word '_'_'_) 'p) ;; expected value = (make-word '_'_'_) |# ;;----------------------------------------------------------------------------------------- ;; draw-next-part : symbol -> true ;; to draw the given symbol on the canvs in "hangman" style (define START (make-posn 10 10)) (define END-1 (make-posn 50 10)) (define END-2 (make-posn (posn-x END-1) 20)) (define HEAD-RADIUS 10) (define HEAD-DIA (* 2 HEAD-RADIUS)) (define HEIGHT 50) (define (draw-next-part a-symbol)   (cond     [(symbol=? 'right-leg a-symbol) (draw-right-leg a-symbol)]     [(symbol=? 'left-leg a-symbol) (draw-left-leg a-symbol)]     [(symbol=? 'left-arm a-symbol) (draw-left-arm a-symbol)]     [(symbol=? 'right-arm a-symbol) (draw-right-arm a-symbol)]     [(symbol=? 'body a-symbol) (draw-body a-symbol)]     [(symbol=? 'head a-symbol) (draw-head a-symbol)]     [(symbol=? 'noose a-symbol) (draw-noose a-symbol)]     [else 'No-match])) (define (draw-noose a-sym)   (and (draw-solid-line START END-1)        (draw-solid-line END-1 END-2))) (define (draw-head a-sym)   (draw-circle (make-posn (posn-x END-2)                           (+ (posn-y END-2) HEAD-RADIUS)) HEAD-RADIUS 'black)) (define (draw-body a-sym)   (draw-solid-line (make-posn (posn-x END-2)                               (+ (posn-y END-2) HEAD-DIA))                    (make-posn (posn-x END-2)                               (+ (posn-y END-2) HEAD-DIA HEIGHT)) 'black)) (define (draw-right-arm a-sym)   (draw-solid-line (make-posn (posn-x END-2)                               (+ (posn-y END-2) HEAD-DIA HEAD-DIA))                    (make-posn (+ (posn-x END-2) (- HEIGHT HEAD-DIA))                               (+ (posn-y END-2) HEAD-DIA)))) (define (draw-left-arm a-sym)   (draw-solid-line (make-posn (posn-x END-2)                               (+ (posn-y END-2) HEAD-DIA HEAD-DIA))                    (make-posn (- (posn-x END-2) (- HEIGHT HEAD-DIA))                               (+ (posn-y END-2) HEAD-DIA)))) (define (draw-right-leg a-symbol)   (draw-solid-line (make-posn (posn-x END-2)                               (+ (posn-y END-2) HEAD-DIA HEIGHT))                    (make-posn (+ (posn-x END-2) (- HEIGHT HEAD-RADIUS))                               (+ (posn-y END-2) (+ HEIGHT HEAD-DIA HEAD-DIA))))) (define (draw-left-leg a-symbol)   (draw-solid-line (make-posn (posn-x END-2)                               (+ (posn-y END-2) HEAD-DIA HEIGHT))                    (make-posn (- (posn-x END-2) (- HEIGHT HEAD-DIA))                               (+ (posn-y END-2) HEIGHT HEAD-DIA HEAD-DIA))))   #|  creation of this HANGMAN was inspired from TRAFFIC-LIGHT (fig. 8) which is an an excellent example of using 'global definitions' for specifying & computing constants. and what? every part of the HANGMAN-body  is in perfect sync with the other. (draw-noose 'kl) (draw-head 'lk) (draw-body 'l) (draw-right-arm 'l) (draw-left-arm 'l) (draw-right-leg 'l) (draw-left-leg 'l) |#  ;; test (hangman make-word reveal draw-next-part) ;;------------  end of programme --------------------------------------