I am writing a small hangman game in scheme and am getting a very weird issue that almost seems like a language specific one.
In my game I have a variable that holds the number of mistakes allowed and on each recursive call of my game loop, I "let" the value to a new one if it needs to be changed. Here is some code to help visualize how I run the game loop.
guessed_list - a list of string characters containing old guesses and one new guess (ex. '("a" "x" "b") where "a" is the new guess)
game_word - '("a" "b" "c")
display_word - a list of string characters containing letters I have matched and hyphens for those I haven't up to this iteration of my game loop (ex '("" "b" "") where "a" from the guessed_list is going to be evaluated this loop iteration)
mistakes_left - The number of mistakes I have before my game should end because of wrong guessed. Initially this starts at 6, but in my current example should be 5 because 1 letter, "x", was guessed incorrectly.
;; Game Loop.
(define (game-loop guessed_list display_word mistakes_left)
(let ((n_mistakes_left
(- mistakes_left (if (contains? game_word (car guessed_list))
0 1))))
(if (= n_mistakes_left 0)
(display n_mistakes_left);; End game output
(let ((display_word (fill-in-guess (list (car guessed_list))
game_word display_word))
(guessed_list (sort guessed_list string<?)))
(display "You have guessed: ")
(display-list guessed_list ", ")
(display "\n\n")
(draw-hangman n_mistakes_left)
(display "\n\nWord: ")
(display-list display_word " ")
(cond ((contains? display_word "_")
(display "\n\nEnter a letter to guess: ")
(game-loop (append (list (symbol->string (read))) guessed_list)
display_word n_mistakes_left))
(else (display "\n\nYou Won!")))))))
I can post my helper methods contains?, fill-in-guess, display-list, draw-hangman if necessary, but all of them work as they should and do not change values of my mistakes_left variable for their functionality.
The problem I am running into is my mistakes_left variable starts out at 6 and passes through fine on the first call of game-loop, but on subsequent calls, gets smaller even when guessing a correct value. I have taken every piece individually, tested it and mistakes_left comes out with the right value until I recurse.
I suspect it has to do with the recurse and "let"ing my variable, but I would like a difinitive answer if anyone could or point out the most likely simple error I am missing!
EDIT:
Here is the rest of the code to test, I still get the issue. I think append worked because it appends the second list to the first, so in that sense cons and append gave me the same input.
(define zero_wrong "
|---------
| |
|
|
|
|
|
|
|
|_______________")
(define one_wrong "
|---------
| |
___
| |. .|
---
|
|
|
|
|
|
|_______________")
(define two_wrong "
|---------
| |
___
| |. .|
---
| |
|
| |
|
|
|
|
|
|_______________")
(define three_wrong "
|---------
| |
___
| |. .|
---
| |
|----
| |
|
|
|
|
|
|_______________")
(define four_wrong "
|---------
| |
___
| |. .|
---
| |
----|----
| |
|
|
|
|
|
|_______________")
(define five_wrong "|---------
| |
___
| |. .|
---
| |
----|----
| |
|
| \\
\\
|
|
|
|_______________")
(define six_wrong "|---------
| |
___
| |x x|
---
| |
----|----
| |
|
| / \\
/ \\
|
|
|
|_______________")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Read list value at x.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (get-str-at x str_lst)
(cond ((equal? x 0)
(car str_lst))
(else
(get-str-at (- x 1) (cdr str_lst))
)
)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Car operation for strings.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (string-car str)
(substring str 0 1)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Cdr operation for strings.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (string-cdr str)
(substring str 1 (string-length str))
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Converts a string into a
;; list of character strings.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (string-to-char-string-list str)
(cond
((equal? (string-cdr str) "")
(list str)
)
(
(append (list (string-car str)) (string-to-char-string-list (string-cdr str)))
)
)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Tests if a list contains a spefified object.
;;
;; Method code from:
;; http://stackoverflow.com/questions/1869116/scheme-built-in-to-check-list-containment
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (contains? list item)
(if (empty? list)
#f
(or (eq? (first list) item)
(contains? (rest list) item)
)
)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Displays a list with the
;; given separater.
;;
;; Base code from:
;; ftp://ftp.cs.utexas.edu/pub/garbage/cs345/schintro-v13/schintro_99.html
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (display-list a_list separater)
(if (null? a_list)
(display "")
(begin
(display (car a_list))
(if (null? (cdr a_list))
(display "")
(display separater))
(display-list (cdr a_list) separater)
)
)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Gets the Xth word in the
;; provided file.
;;
;; Does not check for eof
;; condition, so x must be
;; within range of the file.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (get-word x file)
(cond
((= 1 x)
(read file))
(else
(read file)
(get-word (- x 1) file)
)
)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Returns a list of blanks
;; equal to the number of
;; letters in provided word.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (init-display-word game_word)
(cond
((null? game_word)
(list))
(else
(append (init-display-word (cdr game_word)) '("_"))
)
)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Fills in the blank spaces
;; in the display word with
;; the letter that matches
;; those positions in the
;; game word.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (fill-in-guess letter game_word display_word)
(cond
((null? game_word)
(list)
)
(else
(cond
((equal? letter (list (car game_word)))
(append letter (fill-in-guess letter (cdr game_word) (cdr display_word)))
)
(else
(append (list (car display_word)) (fill-in-guess letter (cdr game_word) (cdr display_word)))
)
)
)
)
)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Draws the hanging man.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (draw-hangman guesses_left)
(cond ((equal? guesses_left 6)
(display zero_wrong))
(else (cond ((equal? guesses_left 5)
(display one_wrong))
(else (cond ((equal? guesses_left 4)
(display two_wrong))
(else (cond ((equal? guesses_left 3)
(display three_wrong))
(else (cond ((equal? guesses_left 2)
(display four_wrong))
(else (cond ((equal? guesses_left 1)
(display five_wrong))
(else (display six_wrong))
)))))))))))
)
contains?predicate do anything other than check if a value is in a list? If not, use the built-in Racket functionmemberinstead – Jack