simplify

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

@@ -8,17 +8,9 @@
 ; http://www.atariarchives.org/basicgames/showpage.php?page=i12
 
 (begin-for-syntax
-  (require racket/match racket/list)
+  (require racket/list)
   (define (gather-unique-ids stx)
-    (define ids empty)
+    (remove-duplicates (map syntax->datum (filter (λ(s) (syntax-property s 'id)) (syntax-flatten stx))) eq?)))
-    (let loop ([x (syntax->datum stx)])
-      (match x
-        [(or (list 'statement (? symbol? id-name) "=" etc ...)
-             (list 'statement "input" (list 'print-list etc ...) (? symbol? id-name) ...)
-             (list 'statement "for" (? symbol? id-name) etc ...)) (set! ids (cons id-name ids))]
-        [(? list?) (map loop x)]
-        [else #f]))
-    (remove-duplicates (flatten ids) eq?)))
 
 (define-macro (basic-module-begin (basic-program PROGRAM-LINE ...))
   (with-pattern

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

@@ -8,12 +8,12 @@ statement : "end" | "stop"
 | "gosub" expr
 | "goto" expr
 | "if" expr /"then" (statement | expr) [/"else" (statement | expr)]
-| "input" [print-list /";"] ID [/"," ID]*
+| "input" [print-list /";"] id [/"," id]*
-| [/"let"] ID "=" expr
+| [/"let"] id "=" expr
 | "print" [print-list]
 | "return"
-| "for" ID /"=" value /"to" value [/"step" value]
+| "for" id /"=" value /"to" value [/"step" value]
-| "next" [ID]
+| "next" [id]
 
 print-list : expr [[";"] [print-list]]
 
@@ -25,10 +25,12 @@ sum : [sum ("+" | "-")] product
 
 product : [product ("*" | "/")] value 
 
-@value : ID
+@value : id
 | id-expr
 | /"(" expr /")"
 | NUMBER
 | STRING
 
-/id-expr : ID [/"(" expr [/"," expr]* /")"]
+/id-expr : id [/"(" expr [/"," expr]* /")"]
+
+@id : ID