diff --git a/beautiful-racket-demo/basic-demo-2/expander.rkt b/beautiful-racket-demo/basic-demo-2/expander.rkt
index 8080938..6d42f5a 100644
--- a/beautiful-racket-demo/basic-demo-2/expander.rkt
+++ b/beautiful-racket-demo/basic-demo-2/expander.rkt
@@ -1,6 +1,5 @@
 #lang br/quicklang
-(require "runtime.rkt"
-         "run.rkt"
+(require "struct.rkt"
          "elements.rkt")
 (provide (rename-out [b-module-begin #%module-begin])
          (all-from-out "elements.rkt"))
@@ -11,17 +10,11 @@
        [(LINE-FUNC ...) (prefix-id "line-" #'(NUM ...))]
        [(VAR-NAME ...) (find-unique-var-names #'(LINE ...))])
     #'(#%module-begin
-       (module configure-runtime br
-         (require basic-demo-2/runtime)
-         (current-basic-port (current-output-port)))
        (define VAR-NAME 0) ...
-       (provide VAR-NAME ...)
        LINE ...
        (define line-table
          (apply hasheqv (append (list NUM LINE-FUNC) ...)))
-       (void (parameterize ([current-output-port
-                             (or (current-basic-port) (open-output-nowhere))])
-               (run line-table))))))
+       (void (run line-table)))))
 
 (begin-for-syntax
   (require racket/list)
@@ -32,4 +25,24 @@
                var-stx)
      #:key syntax->datum)))
 
+(define (run line-table)
+  (define line-vec
+    (list->vector (sort (hash-keys line-table) <)))
+  (with-handlers ([end-program-signal? (λ (exn-val) (void))])
+    (for/fold ([line-idx 0])
+              ([i (in-naturals)]
+               #:break (>= line-idx (vector-length line-vec)))
+      (define line-num (vector-ref line-vec line-idx))
+      (define line-func (hash-ref line-table line-num))
+      (with-handlers
+          ([change-line-signal?
+            (λ (cls)
+              (define clsv (change-line-signal-val cls))
+              (or
+               (and (exact-positive-integer? clsv)
+                    (vector-member clsv line-vec))
+               (line-func #:error (format "line ~a not found" clsv))))])
+        (line-func)
+        (add1 line-idx)))))
+
 
diff --git a/beautiful-racket-demo/basic-demo-2/go.rkt b/beautiful-racket-demo/basic-demo-2/go.rkt
index 1322c25..e415c77 100644
--- a/beautiful-racket-demo/basic-demo-2/go.rkt
+++ b/beautiful-racket-demo/basic-demo-2/go.rkt
@@ -1,5 +1,5 @@
 #lang br
-(require "structs.rkt" "line.rkt")
+(require "struct.rkt" "line.rkt")
 (provide b-goto b-gosub b-return)
 
 (define (b-goto num-expr)
diff --git a/beautiful-racket-demo/basic-demo-2/line.rkt b/beautiful-racket-demo/basic-demo-2/line.rkt
index fb96fda..bd58073 100644
--- a/beautiful-racket-demo/basic-demo-2/line.rkt
+++ b/beautiful-racket-demo/basic-demo-2/line.rkt
@@ -1,5 +1,5 @@
 #lang br
-(require "structs.rkt")
+(require "struct.rkt")
 (provide (all-defined-out))
 
 (define-macro (b-line NUM STATEMENT ...)
diff --git a/beautiful-racket-demo/basic-demo-2/misc.rkt b/beautiful-racket-demo/basic-demo-2/misc.rkt
index 4e2f7b9..1f0e8ad 100644
--- a/beautiful-racket-demo/basic-demo-2/misc.rkt
+++ b/beautiful-racket-demo/basic-demo-2/misc.rkt
@@ -1,5 +1,5 @@
 #lang br
-(require "structs.rkt")
+(require "struct.rkt")
 (provide (all-defined-out))
 
 (define (b-rem val) (void))
diff --git a/beautiful-racket-demo/basic-demo-2/run.rkt b/beautiful-racket-demo/basic-demo-2/run.rkt
index 2a3240f..b264363 100644
--- a/beautiful-racket-demo/basic-demo-2/run.rkt
+++ b/beautiful-racket-demo/basic-demo-2/run.rkt
@@ -1,5 +1,5 @@
 #lang br
-(require "line.rkt" "structs.rkt")
+(require "line.rkt" "struct.rkt")
 (provide run)
 
 (define (run line-table)
diff --git a/beautiful-racket-demo/basic-demo-2/struct.rkt b/beautiful-racket-demo/basic-demo-2/struct.rkt
new file mode 100644
index 0000000..ee0de12
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2/struct.rkt
@@ -0,0 +1,9 @@
+#lang br
+(provide (struct-out end-program-signal)
+         (struct-out change-line-signal)
+         (struct-out line-error))
+
+(struct end-program-signal ())
+(struct change-line-signal (val))
+
+(struct line-error (msg))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/elements.rkt b/beautiful-racket-demo/basic-demo-2a/elements.rkt
new file mode 100644
index 0000000..25942be
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/elements.rkt
@@ -0,0 +1,6 @@
+#lang br
+(require "line.rkt" "go.rkt"
+         "expr.rkt" "misc.rkt")
+(provide
+ (all-from-out "line.rkt" "go.rkt"
+               "expr.rkt" "misc.rkt"))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/expander.rkt b/beautiful-racket-demo/basic-demo-2a/expander.rkt
new file mode 100644
index 0000000..2fa2193
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/expander.rkt
@@ -0,0 +1,37 @@
+#lang br/quicklang
+(require "struct.rkt" "elements.rkt")
+(provide (rename-out [b-module-begin #%module-begin])
+         (all-from-out "elements.rkt"))
+
+(define-macro (b-module-begin (b-program LINE ...))
+  (with-pattern
+      ([((b-line NUM STMT ...) ...) #'(LINE ...)]
+       [(LINE-FUNC ...) (prefix-id "line-" #'(NUM ...))])
+    #'(#%module-begin
+       LINE ...
+       (define line-table
+         (apply hasheqv (append (list NUM LINE-FUNC) ...)))
+       (void (run line-table)))))
+
+(define (run line-table)
+  (define line-vec
+    (list->vector (sort (hash-keys line-table) <)))
+  (with-handlers ([end-program-signal? (λ (exn-val) (void))])
+    (for/fold ([line-idx 0])
+              ([i (in-naturals)]
+               #:break (>= line-idx (vector-length line-vec)))
+      (define line-num (vector-ref line-vec line-idx))
+      (define line-func (hash-ref line-table line-num))
+      (with-handlers
+          ([change-line-signal?
+            (λ (cls)
+              (define clsv (change-line-signal-val cls))
+              (or
+               (and (exact-positive-integer? clsv)
+                    (vector-member clsv line-vec))
+               (error (format "error in line ~a: line ~a not found"
+                              line-num clsv))))])
+        (line-func)
+        (add1 line-idx)))))
+
+
diff --git a/beautiful-racket-demo/basic-demo-2a/expr.rkt b/beautiful-racket-demo/basic-demo-2a/expr.rkt
new file mode 100644
index 0000000..8f274d6
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/expr.rkt
@@ -0,0 +1,7 @@
+#lang br
+(provide b-sum b-expr)
+
+(define (b-sum . vals) (apply + vals))
+
+(define (b-expr expr)
+  (if (integer? expr) (inexact->exact expr) expr))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/go.rkt b/beautiful-racket-demo/basic-demo-2a/go.rkt
new file mode 100644
index 0000000..7d03118
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/go.rkt
@@ -0,0 +1,8 @@
+#lang br
+(require "struct.rkt" "line.rkt")
+(provide b-end b-goto)
+
+(define (b-end) (raise (end-program-signal)))
+
+(define (b-goto num-expr)
+  (raise (change-line-signal num-expr)))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/info.rkt b/beautiful-racket-demo/basic-demo-2a/info.rkt
new file mode 100644
index 0000000..9641805
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/info.rkt
@@ -0,0 +1,4 @@
+#lang info
+
+(define compile-omit-paths 'all)
+(define test-omit-paths 'all)
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/lexer.rkt b/beautiful-racket-demo/basic-demo-2a/lexer.rkt
new file mode 100644
index 0000000..9f95c19
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/lexer.rkt
@@ -0,0 +1,23 @@
+#lang br
+(require brag/support)
+
+(define-lex-abbrev digits (:+ (char-set "0123456789")))
+
+(define basic-lexer
+  (lexer-srcloc
+   [(eof) (return-without-srcloc eof)]
+   ["\n" (token 'NEWLINE lexeme)]
+   [whitespace (token lexeme #:skip? #t)]
+   [(from/stop-before "rem" "\n") (token 'REM lexeme)]
+   [(:or "print" "goto" "end"
+         "+" ":" ";") (token lexeme lexeme)]
+   [digits (token 'INTEGER (string->number lexeme))]
+   [(:or (:seq (:? digits) "." digits)
+         (:seq digits "."))
+    (token 'DECIMAL (string->number lexeme))]
+   [(:or (from/to "\"" "\"") (from/to "'" "'"))
+    (token 'STRING
+           (substring lexeme
+                      1 (sub1 (string-length lexeme))))]))
+
+(provide basic-lexer)
diff --git a/beautiful-racket-demo/basic-demo-2a/line.rkt b/beautiful-racket-demo/basic-demo-2a/line.rkt
new file mode 100644
index 0000000..5e2cdb9
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/line.rkt
@@ -0,0 +1,9 @@
+#lang br
+(require "struct.rkt")
+(provide b-line)
+
+(define-macro (b-line NUM STATEMENT ...)
+  (with-pattern ([LINE-NUM (prefix-id "line-" #'NUM
+                                      #:source #'NUM)])
+    (syntax/loc caller-stx
+      (define (LINE-NUM) (void) STATEMENT ...))))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/main.rkt b/beautiful-racket-demo/basic-demo-2a/main.rkt
new file mode 100644
index 0000000..539100d
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/main.rkt
@@ -0,0 +1,11 @@
+#lang br/quicklang
+(require "parser.rkt" "tokenizer.rkt")
+
+(define (read-syntax path port)
+  (define parse-tree (parse path (make-tokenizer port path)))
+  (strip-bindings
+   #`(module basic-mod basic-demo-2a/expander
+       #,parse-tree)))
+
+(module+ reader
+  (provide read-syntax))
diff --git a/beautiful-racket-demo/basic-demo-2a/misc.rkt b/beautiful-racket-demo/basic-demo-2a/misc.rkt
new file mode 100644
index 0000000..40c969e
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/misc.rkt
@@ -0,0 +1,8 @@
+#lang br
+(require "struct.rkt")
+(provide b-rem b-print)
+
+(define (b-rem val) (void))
+
+(define (b-print . vals)
+  (displayln (string-append* (map ~a vals))))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/parser.rkt b/beautiful-racket-demo/basic-demo-2a/parser.rkt
new file mode 100644
index 0000000..ff898cf
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/parser.rkt
@@ -0,0 +1,13 @@
+#lang brag
+b-program : [b-line] (/NEWLINE [b-line])*
+b-line : b-line-number [b-statement] (/":" [b-statement])*
+@b-line-number : INTEGER
+@b-statement : b-rem | b-end | b-print | b-goto
+b-rem : REM
+b-end : /"end"
+b-print : /"print" [b-printable] (/";" [b-printable])*
+@b-printable : STRING | b-expr
+b-goto : /"goto" b-expr
+b-expr : b-sum
+b-sum : b-number (/"+" b-number)*
+@b-number : INTEGER | DECIMAL
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/sample.rkt b/beautiful-racket-demo/basic-demo-2a/sample.rkt
new file mode 100644
index 0000000..cec4f7f
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/sample.rkt
@@ -0,0 +1,9 @@
+#lang basic-demo-2a
+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 "o" ; "n" ; "e"
+20 print : goto 60.0 : end
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/struct.rkt b/beautiful-racket-demo/basic-demo-2a/struct.rkt
new file mode 100644
index 0000000..d680b77
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/struct.rkt
@@ -0,0 +1,6 @@
+#lang br
+(provide (struct-out end-program-signal)
+         (struct-out change-line-signal))
+
+(struct end-program-signal ())
+(struct change-line-signal (val))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2a/tokenizer.rkt b/beautiful-racket-demo/basic-demo-2a/tokenizer.rkt
new file mode 100644
index 0000000..5c15433
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-2a/tokenizer.rkt
@@ -0,0 +1,10 @@
+#lang br
+(require "lexer.rkt" brag/support)
+
+(define (make-tokenizer ip [path #f])
+  (port-count-lines! ip)
+  (lexer-file-path path)
+  (define (next-token) (basic-lexer ip))
+  next-token)
+
+(provide make-tokenizer)
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/colorer.rkt b/beautiful-racket-demo/basic-demo-3/colorer.rkt
new file mode 100644
index 0000000..a317a63
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/colorer.rkt
@@ -0,0 +1,22 @@
+#lang br
+(require "lexer.rkt" brag/support)
+(provide color-basic)
+
+(define (color-basic port)
+  (define srcloc-tok (basic-lexer port))
+  (match srcloc-tok
+    [(? eof-object?) (values srcloc-tok 'eof #f #f #f)]
+    [else ; reverse-engineer with `match-define`
+     (match-define (srcloc-token (token-struct type val _ _ _ _ _)
+                                 (srcloc _ _ _ pos span)) srcloc-tok)
+     (define (color cat [paren #f])
+       (values (or val "") cat paren pos (+ pos span)))
+     (match type
+       ['STRING (color 'string)]
+       ['REM (color 'comment)]
+       [else (match val
+               [(? number?) (color 'constant)]
+               [(? symbol?) (color 'symbol)]
+               ["(" (color 'parenthesis '|(|)]
+               [")" (color 'parenthesis '|)|)]
+               [else (color 'no-color)])])]))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/elements.rkt b/beautiful-racket-demo/basic-demo-3/elements.rkt
new file mode 100644
index 0000000..62090ca
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/elements.rkt
@@ -0,0 +1,3 @@
+#lang br
+(require "line.rkt" "go.rkt" "if.rkt" "expr.rkt" "for.rkt" "misc.rkt")
+(provide (all-from-out "line.rkt" "go.rkt" "if.rkt" "expr.rkt" "for.rkt" "misc.rkt"))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/expander.rkt b/beautiful-racket-demo/basic-demo-3/expander.rkt
new file mode 100644
index 0000000..8080938
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/expander.rkt
@@ -0,0 +1,35 @@
+#lang br/quicklang
+(require "runtime.rkt"
+         "run.rkt"
+         "elements.rkt")
+(provide (rename-out [b-module-begin #%module-begin])
+         (all-from-out "elements.rkt"))
+
+(define-macro (b-module-begin (b-program LINE ...))
+  (with-pattern
+      ([((b-line NUM STMT ...) ...) #'(LINE ...)]
+       [(LINE-FUNC ...) (prefix-id "line-" #'(NUM ...))]
+       [(VAR-NAME ...) (find-unique-var-names #'(LINE ...))])
+    #'(#%module-begin
+       (module configure-runtime br
+         (require basic-demo-2/runtime)
+         (current-basic-port (current-output-port)))
+       (define VAR-NAME 0) ...
+       (provide VAR-NAME ...)
+       LINE ...
+       (define line-table
+         (apply hasheqv (append (list NUM LINE-FUNC) ...)))
+       (void (parameterize ([current-output-port
+                             (or (current-basic-port) (open-output-nowhere))])
+               (run line-table))))))
+
+(begin-for-syntax
+  (require racket/list)
+  (define (find-unique-var-names stx)
+    (remove-duplicates
+     (for/list ([var-stx (in-list (syntax-flatten stx))]
+                #:when (syntax-property var-stx 'b-id))
+               var-stx)
+     #:key syntax->datum)))
+
+
diff --git a/beautiful-racket-demo/basic-demo-3/expr.rkt b/beautiful-racket-demo/basic-demo-3/expr.rkt
new file mode 100644
index 0000000..8b3dfd7
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/expr.rkt
@@ -0,0 +1,26 @@
+#lang br
+(provide (all-defined-out))
+
+;; b-sum : b-product (("+" | "-")  b-product)*
+(define-macro-cases b-sum
+  [(_ PROD) #'PROD]
+  [(_ LEFT-PROD "+" RIGHT-PROD) #'(+ LEFT-PROD RIGHT-PROD)]
+  [(_ LEFT-PROD "-" RIGHT-PROD) #'(- LEFT-PROD RIGHT-PROD)])
+
+;; b-product : [b-product ("*"|"/"|"%"|"^")] b-value
+(define-macro-cases b-product
+  [(_ VAL) #'VAL]
+  [(_ LEFT "*" RIGHT) #'(* LEFT RIGHT)]
+  [(_ LEFT "/" RIGHT) #'(/ LEFT RIGHT 1.0)]
+  [(_ LEFT "^" RIGHT) #'(expt LEFT RIGHT)]
+  [(_ LEFT "%" RIGHT) #'(modulo LEFT RIGHT)])
+
+(define (b-expr expr)
+  (if (integer? expr) (inexact->exact expr) expr))
+
+(define (b-negative num) (- num))
+
+(define (b-not expr) (if (zero? expr) 1 0))
+
+(define-macro (b-def ID VAR EXPR)
+  #'(set! ID (λ (VAR) EXPR)))
diff --git a/beautiful-racket-demo/basic-demo-3/for.rkt b/beautiful-racket-demo/basic-demo-3/for.rkt
new file mode 100644
index 0000000..4bba4d2
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/for.rkt
@@ -0,0 +1,30 @@
+#lang br
+(require "misc.rkt" "line.rkt")
+(provide b-for b-next)
+
+(define thunk-table (make-hasheq))
+
+(define-macro-cases b-for
+  [(_ LOOP-ID START END) #'(b-for LOOP-ID START END 1)]
+  [(_ LOOP-ID START END STEP)
+   #'(b-let LOOP-ID (let/cc loop-cc
+                      (hash-set! thunk-table
+                                 'LOOP-ID
+                                 (λ ()
+                                   (define next-val (+ LOOP-ID STEP))
+                                   (if (next-val . in-closed-interval? . START END)
+                                       (loop-cc next-val)
+                                       (hash-remove! thunk-table 'LOOP-ID))))
+                      START))])
+
+(define (in-closed-interval? x start end)
+  (if (< start end)
+      (<= start x end)
+      (<= end x start)))
+
+(define-macro (b-next LOOP-ID)
+  #'(begin
+      (unless (hash-has-key? thunk-table 'LOOP-ID)
+        (raise-line-error "next without for"))
+      (define thunk (hash-ref thunk-table 'LOOP-ID))
+      (thunk)))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/go.rkt b/beautiful-racket-demo/basic-demo-3/go.rkt
new file mode 100644
index 0000000..1322c25
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/go.rkt
@@ -0,0 +1,19 @@
+#lang br
+(require "structs.rkt" "line.rkt")
+(provide b-goto b-gosub b-return)
+
+(define (b-goto num-expr)
+  (raise (change-line-signal num-expr)))
+
+(define return-stack empty)
+
+(define (b-gosub num-expr)
+  (let/cc return-cc
+    (push! return-stack return-cc)
+    (b-goto num-expr)))
+
+(define (b-return)
+  (unless (pair? return-stack)
+    (raise-line-error "return without gosub"))
+  (define top-return-k (pop! return-stack))
+  (top-return-k))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/if.rkt b/beautiful-racket-demo/basic-demo-3/if.rkt
new file mode 100644
index 0000000..147d5db
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/if.rkt
@@ -0,0 +1,27 @@
+#lang br
+(require "go.rkt")
+(provide b-if b-comp-expr b-logic-expr)
+
+;; b-if : /"if" b-expr /"then" b-expr [/"else" b-expr]
+(define (b-if cond-expr then-expr [else-expr #f])
+  (cond
+    [(not (zero? cond-expr)) (b-goto then-expr)]
+    [else-expr => b-goto]))
+
+(define bool-int (λ (val) (if val 1 0)))
+(define bi= (compose1 bool-int =))
+(define bi< (compose1 bool-int <))
+(define bi> (compose1 bool-int >))
+
+;; b-comp-expr : b-cond-expr [("and" | "or") b-cond-expr]
+(define-macro-cases b-logic-expr
+  [(_ ARG) #'ARG]
+  [(_ LEFT "and" RIGHT) #'(and LEFT RIGHT)]
+  [(_ LEFT "or" RIGHT) #'(or LEFT RIGHT)])
+
+;; b-cond-expr : b-expr [("=" | "<" | ">") b-expr]
+(define-macro-cases b-comp-expr
+  [(_ ARG) #'ARG]
+  [(_ LEFT "=" RIGHT) #'(bi= LEFT RIGHT)]
+  [(_ LEFT "<" RIGHT) #'(bi< LEFT RIGHT)]
+  [(_ LEFT ">" RIGHT) #'(bi> LEFT RIGHT)])
diff --git a/beautiful-racket-demo/basic-demo-3/info.rkt b/beautiful-racket-demo/basic-demo-3/info.rkt
new file mode 100644
index 0000000..9641805
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/info.rkt
@@ -0,0 +1,4 @@
+#lang info
+
+(define compile-omit-paths 'all)
+(define test-omit-paths 'all)
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/lexer.rkt b/beautiful-racket-demo/basic-demo-3/lexer.rkt
new file mode 100644
index 0000000..04eb928
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/lexer.rkt
@@ -0,0 +1,24 @@
+#lang br
+(require brag/support)
+
+(define-lex-abbrev digits (:+ (char-set "0123456789")))
+
+(define basic-lexer
+  (lexer-srcloc
+   [(eof) (return-without-srcloc eof)]
+   ["\n" (token 'NEWLINE lexeme)]
+   [whitespace (token lexeme #:skip? #t)]
+   [(from/stop-before "rem" "\n") (token 'REM lexeme)]
+   [(:or "print" "goto" "end" "+" ":" "gosub" "return" "let" "=" "-" "for" "to" "step" "next"
+         "if" "then" "else" "and" "or" "<" ">" "*" "/" "(" ")" "^" "!" "%" "input" ";" "def") (token lexeme lexeme)]
+   [(:seq (:+ alphabetic) (:* (:or alphabetic numeric "$"))) (token 'ID (string->symbol lexeme))]
+   [digits (token 'INTEGER (string->number lexeme))]
+   [(:or (:seq (:? digits) "." digits)
+         (:seq digits "."))
+    (token 'DECIMAL (string->number lexeme))]
+   [(:or (from/to "\"" "\"") (from/to "'" "'"))
+    (token 'STRING
+           (substring lexeme
+                      1 (sub1 (string-length lexeme))))]))
+
+(provide basic-lexer)
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/line.rkt b/beautiful-racket-demo/basic-demo-3/line.rkt
new file mode 100644
index 0000000..fb96fda
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/line.rkt
@@ -0,0 +1,17 @@
+#lang br
+(require "structs.rkt")
+(provide (all-defined-out))
+
+(define-macro (b-line NUM STATEMENT ...)
+  (with-pattern ([LINE-NUM (prefix-id "line-" #'NUM
+                                      #:source #'NUM)])
+    (syntax/loc caller-stx
+      (define (LINE-NUM #:error [msg #f])
+        (with-handlers ([line-error? (λ (le) (handle-line-error NUM le))])
+          (when msg (raise-line-error msg))
+          STATEMENT ...)))))
+
+(define (handle-line-error num le)
+  (error (format "error in line ~a: ~a" num (line-error-msg le))))
+
+(define (raise-line-error str) (raise (line-error str)))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/main.rkt b/beautiful-racket-demo/basic-demo-3/main.rkt
new file mode 100644
index 0000000..d48546f
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/main.rkt
@@ -0,0 +1,19 @@
+#lang br/quicklang
+(require "parser.rkt" "tokenizer.rkt")
+
+(module+ reader
+  (provide read-syntax get-info))
+
+(define (read-syntax path port)
+  (define parse-tree (parse path (make-tokenizer port path)))
+  (strip-bindings
+   #`(module basic-mod basic-demo-2/expander
+       #,parse-tree)))
+
+(define (get-info port mod line col pos)
+    (define (handle-query key default)
+      (case key
+        [(color-lexer)
+         (dynamic-require 'basic-demo-2/colorer 'color-basic)]
+        [else default]))
+    handle-query)
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/misc.rkt b/beautiful-racket-demo/basic-demo-3/misc.rkt
new file mode 100644
index 0000000..4e2f7b9
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/misc.rkt
@@ -0,0 +1,17 @@
+#lang br
+(require "structs.rkt")
+(provide (all-defined-out))
+
+(define (b-rem val) (void))
+
+(define (b-print . vals)
+  (displayln (string-append* (map ~a vals))))
+
+(define-macro (b-let ID VAL) #'(set! ID VAL))
+
+(define-macro (b-input ID)
+  #'(b-let ID (let* ([str (read-line)]
+                     [num (string->number (string-trim str))])
+                (or num str))))
+
+(define (b-end) (raise (end-program-signal)))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/parser.rkt b/beautiful-racket-demo/basic-demo-3/parser.rkt
new file mode 100644
index 0000000..c5a7c77
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/parser.rkt
@@ -0,0 +1,37 @@
+#lang brag
+;; program & lines
+b-program : [b-line] (/NEWLINE [b-line])*
+b-line : b-line-number [b-statement] (/":" [b-statement])*
+@b-line-number : INTEGER
+
+;; statements
+@b-statement : b-rem | 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
+b-if : /"if" b-expr /"then" b-expr [/"else" b-expr]
+b-gosub : /"gosub" b-expr
+b-return : /"return"
+b-input : /"input" b-id
+b-def :  /"def" b-id /"(" b-id /")" /"=" b-expr
+b-let : [/"let"] b-id /"=" [STRING | b-expr]
+b-for : /"for" b-id /"=" b-expr /"to" b-expr [/"step" b-expr]
+b-next : /"next" [b-id]
+
+;; expressions with precedence & order
+b-expr : b-logic-expr 
+b-logic-expr : [b-logic-expr ("and" | "or")] b-comp-expr
+b-comp-expr : [b-comp-expr ("=" | "<" | ">")] b-sum
+b-sum : [b-sum ("+"|"-")] b-product
+b-product : [b-product ("*"|"/"|"%"|"^")] b-value
+
+;; values
+@b-value : b-id | b-number | /"(" b-expr /")" | b-not | b-func
+/b-func : b-id /"(" b-expr /")"
+b-not : /"!" b-value
+@b-id : ID
+@b-number : b-positive | b-negative
+@b-positive : INTEGER | DECIMAL
+b-negative : /"-" b-positive
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/private/sample-pseudocode.rkt b/beautiful-racket-demo/basic-demo-3/private/sample-pseudocode.rkt
new file mode 100644
index 0000000..cb306a5
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/private/sample-pseudocode.rkt
@@ -0,0 +1,8 @@
+(define (30) (rem print "'ignored'"))
+(define (35) (void))
+(define (50) (print "never gets here"))
+(define (40) (end))
+(define (60) (print "three") (print (+ 1.0 3)))
+(define (70) (goto (+ 11 18.5 0.5)))
+(define (10) (print "one"))
+(define (20) (print) (goto 60) (end))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/run.rkt b/beautiful-racket-demo/basic-demo-3/run.rkt
new file mode 100644
index 0000000..2a3240f
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/run.rkt
@@ -0,0 +1,23 @@
+#lang br
+(require "line.rkt" "structs.rkt")
+(provide run)
+
+(define (run line-table)
+  (define line-vec
+    (list->vector (sort (hash-keys line-table) <)))
+  (with-handlers ([end-program-signal? (λ (exn-val) (void))])
+    (for/fold ([line-idx 0])
+              ([i (in-naturals)]
+               #:break (>= line-idx (vector-length line-vec)))
+      (define line-num (vector-ref line-vec line-idx))
+      (define line-func (hash-ref line-table line-num))
+      (with-handlers
+          ([change-line-signal?
+            (λ (cls)
+              (define clsv (change-line-signal-val cls))
+              (or
+               (and (exact-positive-integer? clsv)
+                    (vector-member clsv line-vec))
+               (line-func #:error (format "line ~a not found" clsv))))])
+        (line-func)
+        (add1 line-idx)))))
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2/runtime.rkt b/beautiful-racket-demo/basic-demo-3/runtime.rkt
similarity index 100%
rename from beautiful-racket-demo/basic-demo-2/runtime.rkt
rename to beautiful-racket-demo/basic-demo-3/runtime.rkt
diff --git a/beautiful-racket-demo/basic-demo-3/sample-cond.rkt b/beautiful-racket-demo/basic-demo-3/sample-cond.rkt
new file mode 100644
index 0000000..95b5760
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample-cond.rkt
@@ -0,0 +1,8 @@
+#lang basic-demo-2
+10 rem all results should be 1
+20 a = 5
+30 b = 10
+40 print a > 4
+50 print b = 10
+60 print b < 11
+70 print ! (b = 100)
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/sample-def.rkt b/beautiful-racket-demo/basic-demo-3/sample-def.rkt
new file mode 100644
index 0000000..f2d92c1
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample-def.rkt
@@ -0,0 +1,4 @@
+#lang basic-demo-2
+10 rem all results should be 1
+20 def f(x) = x * x
+30 print f((1+2)*3) = 81
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/sample-for.rkt b/beautiful-racket-demo/basic-demo-3/sample-for.rkt
new file mode 100644
index 0000000..3346736
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample-for.rkt
@@ -0,0 +1,8 @@
+#lang basic-demo-2
+10 for a = 1 to 3
+20 print a
+21 for b = 103 to 101 step -1
+22 print b
+23 next b
+30 next a
+40 print "yay"
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/sample-gosub.rkt b/beautiful-racket-demo/basic-demo-3/sample-gosub.rkt
new file mode 100644
index 0000000..b1baafb
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample-gosub.rkt
@@ -0,0 +1,10 @@
+#lang basic-demo-2
+10 gosub 41
+20 print "world"
+30 gosub 100
+31 print "hi"
+35 end
+40 return
+41 print "hello" : return
+100 print "third"
+110 goto 40
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/sample-import.rkt b/beautiful-racket-demo/basic-demo-3/sample-import.rkt
new file mode 100644
index 0000000..7004f51
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample-import.rkt
@@ -0,0 +1,3 @@
+#lang br
+(require basic-demo-2/sample-var)
+(* a a)
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/sample-input.rkt b/beautiful-racket-demo/basic-demo-3/sample-input.rkt
new file mode 100644
index 0000000..8eb14cb
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample-input.rkt
@@ -0,0 +1,4 @@
+#lang basic-demo-2
+5 print "enter your name: "
+10 input A$
+20 print "hello, " ; A$ ; "!"
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/sample-math.rkt b/beautiful-racket-demo/basic-demo-3/sample-math.rkt
new file mode 100644
index 0000000..4c3923f
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample-math.rkt
@@ -0,0 +1,9 @@
+#lang basic-demo-2
+10 rem all results should be 1
+20 print 1 - 2 * 3 + 4 * 5 - 6 = 9
+30 print (1 - 2) * (3 + 4) * (5 - 6) = 7
+40 print 1 / 4 = .25
+50 print 2 ^ 3 = 8
+60 print 9 ^ 0.5 = 3
+70 print 6 % 2 = 0
+80 print 5 % 2 = 1
diff --git a/beautiful-racket-demo/basic-demo-3/sample-var.rkt b/beautiful-racket-demo/basic-demo-3/sample-var.rkt
new file mode 100644
index 0000000..106abb4
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample-var.rkt
@@ -0,0 +1,8 @@
+#lang basic-demo-2
+10 a = 1 : a = 5
+20 gosub 150
+30 a = 25
+40 gosub 150
+50 end
+150 print a + a + a
+160 return
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-3/sample.rkt b/beautiful-racket-demo/basic-demo-3/sample.rkt
new file mode 100644
index 0000000..a3089f6
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/sample.rkt
@@ -0,0 +1,9 @@
+#lang basic-demo
+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"
+20 print : goto 60.0 : end
\ No newline at end of file
diff --git a/beautiful-racket-demo/basic-demo-2/structs.rkt b/beautiful-racket-demo/basic-demo-3/structs.rkt
similarity index 100%
rename from beautiful-racket-demo/basic-demo-2/structs.rkt
rename to beautiful-racket-demo/basic-demo-3/structs.rkt
diff --git a/beautiful-racket-demo/basic-demo-3/tokenizer.rkt b/beautiful-racket-demo/basic-demo-3/tokenizer.rkt
new file mode 100644
index 0000000..5c15433
--- /dev/null
+++ b/beautiful-racket-demo/basic-demo-3/tokenizer.rkt
@@ -0,0 +1,10 @@
+#lang br
+(require "lexer.rkt" brag/support)
+
+(define (make-tokenizer ip [path #f])
+  (port-count-lines! ip)
+  (lexer-file-path path)
+  (define (next-token) (basic-lexer ip))
+  next-token)
+
+(provide make-tokenizer)
\ No newline at end of file