diff --git a/forge/sf.lisp b/forge/sf.lisp
index 0e41101..5ff4de0 100644
--- a/forge/sf.lisp
+++ b/forge/sf.lisp
@@ -9,7 +9,7 @@
   (:export #:forge-env #:vocabulary #:stack #:current-package
            #:*forge-env* #:*input* #:*code*
            #:word #:comp-word
-           #:exec-list #:exec-string #:exec-input #:comp-input #:call
+           #:repl #:exec-list #:exec-string #:exec-input #:comp-input #:call
            #:comp-item
            #:next #:reg #:reg1 #:reg2 #:reg-code
            #:pushd #:popd #:peekd))
@@ -81,6 +81,11 @@
 
 ;;;; code compilation and execution
 
+(defun repl ()
+  (do ((input (read-line) (read-line))) 
+      ((string= input "q") (stack *forge-env*))
+    (exec-string input)))
+
 (defun exec-list (lst)
   (let ((*input* (iter:list-iterator lst)))
     (exec-input)))
@@ -139,7 +144,8 @@
   (:local-nicknames (:f :scopes/forge/sf)
                     (:iter :scopes/util/iter)
                     (:util :scopes/util))
-  (:export #:add #:mul #:dup #:swp 
+  (:export #:add #:mul #:drop #:dup #:swp 
+           #:? #:??
            #:ptr #:get #:put
            #:in #:next 
            #:call #:call-if #:call-while #:comp 
@@ -167,6 +173,10 @@
 
 (f:reg 'dup #'(lambda () (f:pushd (f:peekd))))
 (f:reg 'swp #'(lambda () (let ((a (f:popd)) (b (f:popd))) (f:pushd a) (f:pushd b))))
+(f:reg 'drop #'f:popd)
+
+(f:reg '? #'(lambda () (format t "~a~%" (f:popd))))
+(f:reg '?? #'(lambda () (format t "~a~%" (f:stack f:*forge-env*))))
 
 (f:reg1 'ptr #'util:ptr)
 (f:reg1 'get #'aref)