diff --git a/collects/datalog/lang/reader.rkt b/collects/datalog/lang/reader.rkt
index 8cf7d2a..701c0c8 100644
--- a/collects/datalog/lang/reader.rkt
+++ b/collects/datalog/lang/reader.rkt
@@ -6,11 +6,12 @@
   #:read-syntax (lambda ([source-name #f] [in (current-input-port)])
                   (let ([ast (parse-program in)])
                     (list `(#%module-begin ,@ast))))
-  #:whole-body-readers? #t
+  #:whole-body-readers? #t  
   #:info (lambda (key defval default)
-           ; XXX Should have comment character key
-           ; XXX repl submit
+           ; XXX Should have different comment character key
            (case key
+             [(drracket:submit-predicate)
+              (dynamic-require `datalog/tool/submit 'repl-submit?)]
              [(color-lexer)
               (dynamic-require `datalog/tool/syntax-color 'get-syntax-token)]
              [else (default key defval)]))
diff --git a/collects/datalog/tool/submit.rkt b/collects/datalog/tool/submit.rkt
new file mode 100644
index 0000000..f16281a
--- /dev/null
+++ b/collects/datalog/tool/submit.rkt
@@ -0,0 +1,54 @@
+#lang racket/base
+
+(define (delimiter-pair? x y)
+  (and (char=? x #\() (char=? y #\))))
+
+(define (repl-submit? ip has-white-space?)
+  (let loop ([blank? #t]
+             [string-char #f]
+             [delimiter-stack null]
+             [closed? #f])
+    (let ([c (read-char ip)])
+      (if (eof-object? c)
+          (and closed?
+               (not blank?)
+               (not string-char)
+               (null? delimiter-stack))
+          (case c
+            [(#\. #\? #\~)
+             (if string-char
+                 (loop #f string-char delimiter-stack #f)
+                 (loop #f #f delimiter-stack #t))]
+            [(#\()
+             (if string-char
+                 (loop #f string-char delimiter-stack #f)
+                 (loop #f #f (cons c delimiter-stack) #f))]
+            [(#\))
+             (cond
+               [string-char
+                (loop #f string-char delimiter-stack #f)]
+               [(and (pair? delimiter-stack)
+                     (delimiter-pair? (car delimiter-stack) c))
+                (loop #f #f (cdr delimiter-stack) #f)]
+               [else
+                (loop #f #f delimiter-stack #f)])]
+            [(#\")
+             (cond
+               [(and string-char (char=? c string-char))
+                (loop #f #f delimiter-stack #f)]
+               [string-char
+                (loop #f string-char delimiter-stack #f)]
+               [else
+                (loop #f c delimiter-stack #f)])]
+            [(#\\)
+             (if string-char
+                 (begin (read-char ip)
+                        (loop #f string-char delimiter-stack #f))
+                 (loop #f string-char delimiter-stack #f))]
+            [else
+             (loop (and blank? (char-whitespace? c))
+                   string-char
+                   delimiter-stack
+                   closed?)])))))
+
+(provide repl-submit?)
\ No newline at end of file
diff --git a/collects/datalog/tool/syntax-color.rkt b/collects/datalog/tool/syntax-color.rkt
index 6078175..5966b2e 100644
--- a/collects/datalog/tool/syntax-color.rkt
+++ b/collects/datalog/tool/syntax-color.rkt
@@ -1,4 +1,4 @@
-#lang racket
+#lang racket/base
 (require parser-tools/lex
          (prefix-in : parser-tools/lex-sre)
          "../private/lex.rkt")
@@ -26,11 +26,11 @@
    [comment-re
     (syn-val lexeme 'comment #f start-pos end-pos)]
    [variable-re
-    (syn-val lexeme 'identifier #f start-pos end-pos)]
+    (syn-val lexeme 'symbol #f start-pos end-pos)]
    [identifier-re
-    (syn-val lexeme 'keyword #f start-pos end-pos)]
+    (syn-val lexeme 'identifier #f start-pos end-pos)]
    [(:or #\) #\() (syn-val lexeme 'parenthesis #f start-pos end-pos)]
-   [(:or #\= #\? #\~ #\. #\, ":-") (syn-val lexeme 'default #f start-pos end-pos)]
+   [(:or #\= #\? #\~ #\. #\, ":-") (syn-val lexeme 'parenthesis #f start-pos end-pos)]
    [(eof) (syn-val lexeme 'eof #f start-pos end-pos)]
    [#\" ((colorize-string start-pos) input-port)]
    [any-char (syn-val lexeme 'error #f start-pos end-pos)]))
\ No newline at end of file