Refinement of Check Syntax arrows

bracket/bracket-lang.rkt

@@ -19,6 +19,3 @@
      #'(begin 
          (define sym 'sym) ...
          (set! sym 'sym) ...)]))
-
-
-

bracket/bracket.rkt

@@ -728,32 +728,7 @@
 
 
 
-#;(module pattern-matching racket
-    (require (submod ".." expression))
-    (define (linear-form u x)
-      ; u expression, x a symbol
-      (if (eq? u x) 
-          (list 1 0)
-          (case (kind u)
-            [(symbol-id integer fraction real complex)
-             (list 0 u)]
-            [(Times)
-             (if (free-of u x)
-                 (list 0 u)
-                 (let ([u/x (Quotient u x)])
-                   (if (Free-of u/x x)
-                       (list u/x 0)
-                       #f)))]
-            [(Plus)
-             (let ([f (linear-form (operand u 1) x)])   
-               (and f
-                    (let ([r (linear-form (Minus u (operand u 1)))])
-                      (and r
-                           (list (+ (operand f 0) (operand r 0))
-                                 (+ (operand f 1) (operand r 1)))))))]
-            [else
-             (and (free-of u x)
-                  (list 0 u))]))))
+
 
 (module equation-expression racket
   (require (submod ".." expression))
@@ -1215,7 +1190,35 @@
   ;                (eq? (Kind exponent) 'integer)
   ;                (> exponent 1))
   )
-   
+
+
+#;(module pattern-matching racket
+  (require (submod ".." expression)
+           (submod ".." bracket))
+  (define (linear-form u x)
+    ; u expression, x a symbol
+    (if (eq? u x) 
+        (list 1 0)
+        (case (kind u)
+          [(symbol-id integer fraction real complex)
+           (list 0 u)]
+          [(Times)
+           (if (free-of u x)
+               (list 0 u)
+               (let ([u/x (Quotient u x)])
+                 (if (Free-of u/x x)
+                     (list u/x 0)
+                     #f)))]
+          [(Plus)
+           (let ([f (linear-form (operand u 1) x)])   
+             (and f
+                  (let ([r (linear-form (Minus u (operand u 1)))])
+                    (and r
+                         (list (+ (operand f 0) (operand r 0))
+                               (+ (operand f 1) (operand r 1)))))))]
+          [else
+           (and (free-of u x)
+                (list 0 u))]))))
 
 (module test racket
   (require (submod ".." symbolic-application)

bracket/examples/newton-iteration.rkt

@@ -24,7 +24,7 @@ NestList(f,expr,n):=if(n=0, List(expr), Cons(expr, NestList(f,f(expr),n-1)));
 % Use it!
 NestList(next,x0,7);
 % NestList also works symbolically.
-DeclareVars(g,x);
-NestList(g,x,5);
+%DeclareVars(g,x);
+%NestList(g,x,5);
 % We can get the first approximations as symbolical expressions. Not pretty.
-NestList(next,x,2);
+%NestList(next,x,2);

bracket/lang/parser.rkt

@@ -145,11 +145,14 @@
 ; - A number representing the ending position of the match (or #f if eof).
 
 (define (syn-val a b c d e)
-  (values a b c 
-          (position-offset d)
+  (values a ; string with mathching text
+          b ; symbol in '(comment white-space no-color eof)
+          c ; symbol in '(|(| |)| |[| |]| |{| |}|) or #f.
+          (position-offset d)    ; start pos
           #;(position-offset e) 
-          (max (position-offset e)
-               (+ (position-offset d) 1))))
+          (max                   ; end pos
+           (position-offset e)
+           (+ (position-offset d) 1))))
 
 (define color-lexer
   ; REMEMBER to restart DrScheme to test any changes in the color-lexer.
@@ -175,8 +178,10 @@
    ; different identifiers to see whether := or ( comes after the identfier.
    ; This is enough to prevent shift/reduce conflicts between atom, definition,
    ; and application.
-   [(:or identifier:= identifierOP identifier)
+   [":="
     (syn-val lexeme 'symbol #f start-pos end-pos)]
+   [identifier
+    (syn-val lexeme 'symbol #f start-pos end-pos)]      
    [(:+ digit) 
     (syn-val lexeme 'constant #f start-pos end-pos)]
    [(:: (:+ digit) #\. (:* digit)) 

bracket/lang/reader.rkt

@@ -69,7 +69,7 @@
               (define list-ref List-ref)
               (define-syntax (define stx)
                 (syntax-case stx () [(_ . more) #'(Define . more)]))
-              (require bracket/lang/parser)
+              (require bracket/lang/parser)              
               #;(current-read-interaction
                  (λ (_ in)
                    (parse-expression 'repl #'repl in)))