From 9ceef60254f0917aa6e4d9e14a643d090ff570d7 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Tue, 19 Apr 2016 13:00:38 -0700
Subject: [PATCH] prelim jumping

---
 beautiful-racket/br/demo/basic/expander.rkt | 21 ++++++++++++---------
 beautiful-racket/br/demo/basic/sinewave.bas | 15 +++++++++++++++
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/beautiful-racket/br/demo/basic/expander.rkt b/beautiful-racket/br/demo/basic/expander.rkt
index a67c7cd..77dbcd7 100644
--- a/beautiful-racket/br/demo/basic/expander.rkt
+++ b/beautiful-racket/br/demo/basic/expander.rkt
@@ -17,7 +17,7 @@
       (procedure-rename (λ xs (cons 'id xs)) (format-datum "undefined:~a" 'id))))
 
 (define #'(basic-program CR-LINE ...)
-  #'(begin CR-LINE ...))
+  #'(basic-run CR-LINE ...))
 
 (define (basic-run . lines)
   (define program-lines (list->vector lines))
@@ -34,23 +34,23 @@
                              idx)))
               (add1 line-idx)))))
 
-(define-cases #'cr-line ; erases "cr"s
-  [#'(_ "cr" LINE)  #'LINE]
-  [#'(_ "cr") #'(begin)])
+(define #'(cr-line "cr" ARG ...)
+  #'(begin ARG ...))
 
 (define #'(line NUMBER STATEMENT ...)
-  #'(begin STATEMENT ...))
+  #'(cons NUMBER (λ _ STATEMENT ...)))
+
+
+(define vars (make-hasheq))
 
 (define-cases #'statement
-  [#'(statement ID "=" EXPR) (if (identifier-binding #'ID)
-                                 #'(set! ID EXPR)
-                                 #'(define ID EXPR))]
+  [#'(statement ID "=" EXPR) #'(hash-set! vars 'ID EXPR)]
   [#'(statement PROC ARG ...) #'(PROC ARG ...)])
 
 (define-cases #'value
   [#'(value "(" EXPR ")") #'EXPR]
   [#'(value ID "(" ARG ... ")") #'(ID ARG ...)]
-  [#'(value DATUM) #'DATUM])
+  [#'(value ID-OR-DATUM) #'(hash-ref vars 'ID-OR-DATUM (λ _ ID-OR-DATUM))])
 
 (define #'(expr EXPR) #'EXPR)
 
@@ -77,4 +77,7 @@
 (define (INT num) (inexact->exact (round num)))
 (define (SIN num) (sin num))
 
+(define (GOTO where)
+  where)
+
 (define (comment . args) void)
diff --git a/beautiful-racket/br/demo/basic/sinewave.bas b/beautiful-racket/br/demo/basic/sinewave.bas
index 6070937..2eb140e 100644
--- a/beautiful-racket/br/demo/basic/sinewave.bas
+++ b/beautiful-racket/br/demo/basic/sinewave.bas
@@ -1,3 +1,18 @@
 #lang br/demo/basic
 10 PRINT TAB(30);"SINE WAVE"
 20 PRINT TAB(15);"CREATIVE COMPUTING  MORRISTOWN, NEW JERSEY"
+30 PRINT: PRINT: PRINT: PRINT: PRINT
+40 REMARKABLE PROGRAM BY DAVID AHL
+50 B=0
+100 REM  START LONG LOOP
+110 FOR T=0 TO 40 STEP .25
+120 A=INT(26+25*SIN(T))
+130 PRINT TAB(A);
+140 IF B=1 THEN 180
+150 PRINT "CREATIVE"
+160 B=1
+170 GOTO 200
+180 PRINT "COMPUTING"
+190 B=0
+200 NEXT T
+999 END
\ No newline at end of file