fix grammar bug

beautiful-racket-demo/regexcellent-demo/grammar.rkt

@@ -7,10 +7,10 @@ lookbehind : /"(" /"?" /"<" /"=" pat /")"
 lookahead : /"(" /"?" /"=" pat /")"
 choice : pat (/"|" pat)+
 repeat : repeatable [("*" | "+") ["?"] | "?"]
-@repeatable : group | any | start | end | literals | chars
+@repeatable : group | any | start | end | literal | chars
 group : /"(" pat /")"
 any : /"."
 start : /"^"
 end : /"$"
-literals : LITERAL+
-chars : /"[" LITERAL* /"]"
+literal : LITERAL
+chars : /"[" literal* /"]"

beautiful-racket-demo/regexcellent-demo/main.rkt

@@ -5,23 +5,22 @@
 (module+ reader
   (provide read-syntax))
 
-(define-lex-abbrev regex-chars (char-set "()*+?.^$|<!=[]"))
+(define-lex-abbrev reserved-chars (char-set "()*+?.^$|<!=[]"))
   
 (define tokenize
   (lexer
    [(:+ "\n") (token 'NEWLINE lexeme)]
    [(from/stop-before ";" "\n") (token 'COMMENT #:skip? #t)]
    [(:+ whitespace) (token 'SP lexeme #:skip? #t)]
-   [regex-chars lexeme]
+   [reserved-chars lexeme]
    [alphabetic (token 'LITERAL lexeme)]))
 
 (define (read-syntax src ip)
   (define parse-tree (parse (λ () (tokenize ip))))
   (strip-context
    (with-syntax ([PT parse-tree])
-     #'(module regexcellent-mod regexcellent-demo
-         (for ([line (in-list PT)])
-           (displayln line))))))
+     #'(module mod-name regexcellent-demo
+         (for-each displayln PT)))))
 
 (define-macro (top . LINES) #'(list . LINES))
 
@@ -31,15 +30,16 @@
 (define (pat . xs)
   (if (= (length xs) 1)
       (car xs)
-      (format "a sequence starting with ~a" (string-join xs ", followed by "))))
+      (format "a sequence (~a)" (string-join xs ", followed by "))))
 
 (define (lookbehind pat)
   (format "a lookbehind assertion of ~a" pat))
+
 (define (lookahead pat)
   (format "a lookahead assertion of ~a" pat))
 
 (define (choice . pats)
-  (format "a choice of ~a" (string-join pats "; or ")))
+  (format "a choice of ~a" (string-join pats " or ")))
 
 (define (repeat thing [quantifier #f] [maybe-non-greedy? #f])
   (string-join
@@ -58,9 +58,9 @@
 
 (define (any) "any character")
 (define (start) "the start of the input")
-(define (end) "the end of the input")
+(define (end) "the end of the input") 
+
+(define (literal str) (~v str))
 
-(define (literals . strs)
-  (format "the literal string ~v" (string-join strs "")))
 (define (chars . lits)
-  (format "any member of the character set {~a}" (string-join (map ~v lits) ", ")))
+  (format "any member of the character set {~a}" (string-join (map ~a lits) " ")))