tokenize recognizes #@ as a fasl header and calls $fasl-read (in

libfasl.ss).

src/libfasl.ss

@@ -226,3 +226,21 @@
           (error 'fasl-write "~s is not an output port" port))
         (do-fasl-write x port)])))
 
+
+(let ()
+  (define who 'fasl-read)
+  (define (assert-eq? x y)
+    (unless (eq? x y)
+      (error who "Expected ~s, got ~s\n" y x)))
+  (define (do-read p)
+    (let ([h (read-char p)])
+      (case h
+        [else 
+         (error who "Unexpected ~s as a fasl object header" h)])))
+  (primitive-set! '$fasl-read
+    (lambda (p)
+      (assert-eq? (read-char p) #\I)
+      (assert-eq? (read-char p) #\K)
+      (assert-eq? (read-char p) #\0)
+      (assert-eq? (read-char p) #\1)
+      (do-read p))))

src/libtokenizer.ss

@@ -405,6 +405,8 @@
                     [else
                      (error 'tokenize
                         "invalid char ~a inside gensym" c)])))]))]
+        [($char= #\@ c)
+         (cons 'datum ($fasl-read p))]
         [else 
          (unread-char c p)
          (error 'tokenize "invalid syntax #~a" c)])))

src/makefile.ss

@@ -115,6 +115,7 @@
     trace-symbol! untrace-symbol!  make-traced-procedure
     fixnum->string 
     $interrupted? $unset-interrupted! $do-event
+    $fasl-read
     ;;; TODO: must open-code
 
     $make-port/input $make-port/output $make-port/both