bam

beautiful-racket/br/demo/basic/expander.rkt

@@ -27,8 +27,7 @@
       (displayln (format "got unbound identifier: ~a" 'id))
       (procedure-rename (λ xs (cons 'id xs)) (format-datum "undefined:~a" 'id))))
 
-(define #'(program LINE ...)
-  #'(run (list LINE ...)))
+(define #'(program LINE ...) #'(run (list LINE ...)))
 
 (define (run lines)
   (define program-lines (list->vector (filter (λ(ln) (not (equal? ln "cr"))) lines)))
@@ -84,15 +83,20 @@
 (define (PRINT args)
   (match args
     [(list) (displayln "")]
-    [(list items ... ";" pl) (begin (for-each display items) (PRINT pl))]
-    [(list items ... ";") (for-each display items)]
-    [(list items ...) (for-each displayln items)]))
+    [(list print-list-item ... ";" pl) (begin (for-each display print-list-item) (PRINT pl))]
+    [(list print-list-item ... ";") (for-each display print-list-item)]
+    [(list print-list-item ...) (for-each displayln print-list-item)]))
 
 (define (TAB num) (make-string num #\space))
 (define (INT num) (inexact->exact (round num)))
 (define (SIN num) (sin num))
 (define (RND num) (* (random) num))
 
+(define #'(INPUT PRINT-LIST ";" ID)
+  #'(begin
+    (PRINT (append PRINT-LIST (list ";")))
+    (set! ID (read-line))))
+
 (define (GOTO where)
   where)
 

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

@@ -1,7 +1,7 @@
 #lang ragg
 
 ;; recursive rules destucture easily in the expander
-program : line [CR line]*
+program : [line [CR line]*]
 
 line: INTEGER statement+
 
@@ -9,7 +9,7 @@ statement : "END"
 | "FOR" ID "=" expr "TO" expr ["STEP" expr]     
 | "GOTO" expr
 | "IF" expr "THEN" (statement | expr) ; change: add expr
-| "INPUT" ID+
+| "INPUT" print-list ";" ID
 | ["LET"] ID "=" expr ; change: make "LET" opt
 | "NEXT" ID+
 | "PRINT" print-list