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beautiful-racket-demo/basic-demo/lexer.rkt

@@ -1,15 +1,16 @@
 #lang br
 (require brag/support)
 
+(define-lex-abbrev digits (:+ (char-set "0123456789")))
+
 (define basic-lexer
   (lexer-srcloc
    [(eof) (return-without-srcloc eof)]
    [whitespace (token lexeme #:skip? #t)]
-   [(from/to "rem" #\newline) (token 'REM lexeme)]
+   [(from/to "rem" "\n") (token 'REM lexeme)]
    [(:or "print" "goto" "end" "+" ":") lexeme]
-   [(:+ numeric) (token 'INTEGER (string->number lexeme))]
+   [digits (token 'INTEGER (string->number lexeme))]
-   [(:or (:seq (:+ numeric) ".")
+   [(:or (:seq digits ".") (:seq (:? digits) "." digits))
-         (:seq (:* numeric) "." (:+ numeric)))
     (token 'DECIMAL (string->number lexeme))]
    [(from/to "\"" "\"")
     (token 'STRING (trim-ends "\"" lexeme "\""))]))

beautiful-racket-demo/basic-demo/sample.rkt

@@ -2,7 +2,7 @@
 30 rem print "ignored"
 50 print "never gets here"
 40 end
-60 print "three" : print 2 + 2
+60 print "three" : print 1.0 + 3
-70 goto 11 + 10.5 + 8.5
+70 goto 11. + 18.5 + .5
 10 print "one"
-20 print : goto 60 : end
+20 print : goto 60.0 : end