我是Lisp Scheme的新手。 我正在尝试使用DrRacket IDE上的Lisp Scheme编写Caesar密码程序。 我得到以下
paragraph: undefined;
cannot reference undefined identifier
我的代码如下
;; ENVIRONMENT
;; contains "ctv", "vtc",and "reduce" definitions
(load "include.ss")
;; contains a test document consisting of three paragraphs.
(load "document.ss")
;; contains a test-dictionary, which has a much smaller dictionary for testing
;; the dictionary is needed for spell checking
(load "test-dictionary.ss")
(load "dictionary.ss") ;; the real thing with 45,000 words
;; -----------------------------------------------------
;; HELPER FUNCTIONS
;; returns a function to "spin" arg "letter" by "val"
(define spin
(lambda (val)
(lambda (letter)
(vtl(modulo (+ val (ltv letter)) 26)))))
;; returns a function to spin current letter to value of 'e'
(define spin_to_e
(lambda (pos)
(+ (- 26 pos) 4)
))
;;counts how many of a target letter are in a word. (count_letter 'x) returns a func that counts x in a list. ((count_letter 'x) '(list)) counts x in list
(define count_letter
(lambda (ltr)
(lambda (lis)
(if (null? lis)
0
(if (equal? (car lis) ltr)
(+ 1 ((count_letter ltr) (cdr lis)))
(+ 0 ((count_letter ltr) (cdr lis)))))
)))
;;counts how many elements in a list == #t
(define count_true
(lambda (l)
(reduce + (map (lambda (x) (if (equal? x #t) 1 0)) l) 0) )) ;;HERE'S MY USE OF REDUCE. Count's how many #t's are in a list
;;show me the truth
(define containstrue?
(lambda (l)
(if (null? l)
#f
(if (equal? (car l) #t)
#t
(containstrue? (cdr l))))
))
(define (sortappend l piece) ;;adds one by one, putting element at the head if >= current head
(if (null? l) (append '() l)
(if (>= piece (car l))
(cons piece l)
(append l (list piece)))))
(define find_index ;;finds target element, returns its "index" from 0 26
(lambda (l t)
(if (null? l) 0
(if (equal? t (car l))
0
(+ 1 (find_index (cdr l) t)) ))
))
;; *** CODE FOR ANY HELPER FUNCTION GOES HERE ***
;; -----------------------------------------------------
;; SPELL CHECKER FUNCTION
;;check a word's spell correctness
;;INPUT:a word(a global variable "dictionary" is included in the file "test-dictionary.ss", and can be used directly here)
;;OUTPUT:true(#t) or false(#f)
(define spell-checker
(lambda (w)
(if (member w dictionary) #t #f)
;; DONE
))
;; -----------------------------------------------------
;; ENCODING FUNCTIONS
;;(define (multiplyBy n) (lambda (x) (* n x)))
;;((multiplyBy 5) 2) ^^how to ret a function
;;generate an Caesar Cipher single word encoders
;;INPUT:a number "n"
;;OUTPUT:a function, whose input=a word, output=encoded word
(define encode-n
(lambda (n);;"n" is the distance, eg. n=3: a->d,b->e,...z->c
(lambda (w);;"w" is the word to be encoded
(map (spin n) w) ;;performs helper func 'spin' on every letter in given word w
)))
;;encode a document
;;INPUT: a document "d" and a "encoder"
;;OUTPUT: an encoded document using a provided encoder
(define encode-d;;this encoder is supposed to be the output of "encode-n"
(lambda (d encoder)
(if (null? d) '() ;;catches recursive base case, returns empty list
(append (cons(map encoder (car d)) '()) (encode-d (cdr d) encoder) )) ;;encode first para, concat w/ recursive call on rest
))
;; -----------------------------------------------------
;; DECODE FUNCTION GENERATORS
;; 2 generators should be implemented, and each of them returns a decoder
;;generate a decoder using brute-force-version spell-checker
;;INPUT:an encoded paragraph "p"
;;OUTPUT:a decoder, whose input=a word, output=decoded word
(define Gen-Decoder-A
(lambda (p)
(define return_decoder
(lambda (i)
(encode-n i)
))
(define valid_wordcounts
(map count_true
(list
(map spell-checker (map (encode-n 0) p))
(map spell-checker (map (encode-n 1) p))
(map spell-checker (map (encode-n 2) p))
(map spell-checker (map (encode-n 3) p))
(map spell-checker (map (encode-n 4) p))
(map spell-checker (map (encode-n 5) p))
(map spell-checker (map (encode-n 6) p))
(map spell-checker (map (encode-n 7) p))
(map spell-checker (map (encode-n 8) p))
(map spell-checker (map (encode-n 9) p))
(map spell-checker (map (encode-n 10) p))
(map spell-checker (map (encode-n 11) p))
(map spell-checker (map (encode-n 12) p))
(map spell-checker (map (encode-n 13) p))
(map spell-checker (map (encode-n 14) p))
(map spell-checker (map (encode-n 15) p))
(map spell-checker (map (encode-n 16) p))
(map spell-checker (map (encode-n 17) p))
(map spell-checker (map (encode-n 18) p))
(map spell-checker (map (encode-n 19) p))
(map spell-checker (map (encode-n 20) p))
(map spell-checker (map (encode-n 21) p))
(map spell-checker (map (encode-n 22) p))
(map spell-checker (map (encode-n 23) p))
(map spell-checker (map (encode-n 24) p))
(map spell-checker (map (encode-n 25) p)))))
(return_decoder
(find_index valid_wordcounts (apply max valid_wordcounts)))
))
;;generate a decoder using frequency analysis
;;INPUT:same as above ;;sample of a doc, so a para
;;OUTPUT:same as above
(define Gen-Decoder-B
(lambda (p)
(define return_decoder
(lambda (i)
(encode-n i)
))
(define lettercounts
(list
(reduce + (map (count_letter 'a)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'b)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'c)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'd)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'e)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'f)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'g)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'h)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'i)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'j)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'k)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'l)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'm)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'n)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'o)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'p)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'q)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'r)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 's)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 't)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'u)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'v)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'w)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'x)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'y)(reduce append (list p) '())) 0)
(reduce + (map (count_letter 'z)(reduce append (list p) '())) 0)))
(return_decoder (spin_to_e (find_index lettercounts (apply max lettercounts))))
))
;; -----------------------------------------------------
;; CODE-BREAKER FUNCTION
;;a codebreaker
;;INPUT: an encoded document(of course by a Caesar's Cipher), a decoder(generated by functions above)
;;OUTPUT: a decoded document
(define Code-Breaker
(lambda (d decoder)
(if (null? d) '() ;;catches recursive base case, returns empty list
(append (cons(map decoder (car d)) '()) (Code-Breaker (cdr d) decoder)) ) ;;encode first para, concat w/ recursive call on rest
))
;; -----------------------------------------------------
;; EXAMPLE APPLICATIONS OF FUNCTIONS
(spell-checker '(h e l l o))
(define add5 (encode-n 5))
(encode-d document add5)
;(define decoderSP1 (Gen-Decoder-A paragraph))
(define decoderFA1 (Gen-Decoder-B paragraph))
(Code-Breaker document decoderSP1)
IDE在代码的第二行显示错误
(define decoderFA1 (Gen-Decoder-B paragraph)).
错误是由段落引起的。
帮我修复此错误。在此先感谢您的帮助 我有必要的外部文件，但那些只包含列表
答案 0 :(得分：1)
您正在使用DrRacket编写Scheme程序。由于DrRacket可以使用多种语言，因此您需要选择R5RS Scheme作为您的语言：
1. In the lower left corner of DrRacket, click the drop down menu.
2. Click "Choose Language..."
3. Choose R5RS Scheme.
还要记住将文件“include.ss”，“document.ss”，“test-dictionary.ss”和“dictionary.ss”复制到与您自己的源文件相同的目录中。
PS：这是这个项目吗？ https://github.com/T-G-P/CaeserDawg/blob/master/proj2.pdf