adjust rem semantics

beautiful-racket-demo/basic-demo-2/colorer.rkt

@@ -3,14 +3,13 @@
 (provide basic-colorer)
 
 (define (basic-colorer port)
-  (define next-char (peek-char port))
-  (define (handle-read-error exn)
+  (define (handle-lexer-error exn)
     (define exn-srclocs (exn:fail:read-srclocs exn))
-    (srcloc-token (token 'ERROR (string next-char)) (car exn-srclocs)))
-  (define srcloc-tok (with-handlers ([exn:fail:read? handle-read-error])
+    (srcloc-token (token 'ERROR) (car exn-srclocs)))
+  (define srcloc-tok (with-handlers ([exn:fail:read? handle-lexer-error])
                        (basic-lexer port)))
-  (cond 
-    [(eof-object? srcloc-tok) (values srcloc-tok 'eof #f #f #f)]
+  (match srcloc-tok
+    [(? eof-object?) (values srcloc-tok 'eof #f #f #f)]
     [else
      (match-define (srcloc-token (token-struct type val _ _ _ _ _)
                                  (srcloc _ _ _ pos span)) srcloc-tok)
@@ -26,5 +25,3 @@
                  [")" '(parenthesis |)|)]
                  [else '(no-color #f)])]))
      (values (or val "") cat paren pos (+ pos span))]))
-
-(apply-colorer basic-colorer "foo")

beautiful-racket-demo/basic-demo-2/parser.rkt

@@ -1,13 +1,13 @@
 #lang brag
 ;; program & lines
 b-program : [b-line] (/NEWLINE [b-line])*
-b-line : b-line-number [b-statement] (/":" [b-statement])*
+b-line : b-line-number [b-statement] (/":" [b-statement])* [b-rem]
 @b-line-number : INTEGER
+b-rem : REM
 
 ;; statements
-@b-statement : b-rem | b-end | b-print | b-let | b-input | b-def
+@b-statement : b-end | b-print | b-let | b-input | b-def
              | b-goto | b-gosub | b-return | b-for | b-next | b-if
-b-rem : REM
 b-end : /"end"
 b-print : /"print" [STRING | b-expr] (/";" [STRING | b-expr])*
 b-goto : /"goto" b-expr

beautiful-racket-demo/basic-demo-2/sample.rkt

@@ -1,9 +1,9 @@
-#lang basic-demo
+#lang basic-demo-2
 30 rem print 'ignored'
 35
 50 print "never gets here"
 40 end
 60 print 'three' : print 1.0 + 3
 70 goto 11. + 18.5 + .5
-10 print "one"
+10 print "o" ; "n" ; "e"
 20 print : goto 60.0 : end

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

@@ -1,8 +1,8 @@
 #lang brag
 b-program : [b-line] (/NEWLINE [b-line])*
-b-line : b-line-number [b-statement] (/":" [b-statement])*
+b-line : b-line-number [b-statement] (/":" [b-statement])* [b-rem]
 @b-line-number : INTEGER
-@b-statement : b-rem | b-end | b-print | b-goto
+@b-statement : b-end | b-print | b-goto
 b-rem : REM
 b-end : /"end"
 b-print : /"print" [b-printable] (/";" [b-printable])*

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

@@ -4,6 +4,6 @@
 50 print "never gets here"
 40 end
 60 print 'three' : print 1.0 + 3
-70 goto 11. + 18.5 + .5
+70 goto 11. + 18.5 + .5 rem ignored
 10 print "o" ; "n" ; "e"
 20 print : goto 60.0 : end