diff --git a/src/cljs/emptyhead/newlib/delegate.cljs b/src/cljs/emptyhead/newlib/delegate.cljs
index 32f73dd..ce40e19 100644
--- a/src/cljs/emptyhead/newlib/delegate.cljs
+++ b/src/cljs/emptyhead/newlib/delegate.cljs
@@ -13,6 +13,13 @@
   (let [remover (thought/register-thought! [:EH :CORE :NOP] :ext-stages [[:EH :MSG :REMOVE-DELEGATE msg del]])]
     (eval/execute! remover)))
 
+
+;; Forget idea stored in `thought`'s data. Used to make destructors.
+(def/define! [:EH :IDEA :FORGET]
+  (fn  [thought parent]
+    (idea/forget-idea! (thought/data thought))
+    [parent nil]))
+
 ;; FIXME Delegate order is currently undefined! Give this a proper order.
 ;; FIXME needs to be called with a list as second arg??
 (defn add-delegate
@@ -34,6 +41,5 @@
   [msg]
   (let [stage [:EH :MSG :DELEGATE msg]
         dels (-> (thought/register-thought! [:EH :CORE :CONTAINER] :ext-stages [stage])
-        eval/execute! thought/pop-stack second)]
-    (mapcat #(cons % (get-delegates %)) dels)
-    ))
+                 eval/execute! thought/empty-stack second)]
+    (mapcat #(cons % (get-delegates %)) dels)))
diff --git a/src/cljs/emptyhead/newlib/math/arithmetic.cljs b/src/cljs/emptyhead/newlib/math/arithmetic.cljs
index e9a673d..0eaf5e4 100644
--- a/src/cljs/emptyhead/newlib/math/arithmetic.cljs
+++ b/src/cljs/emptyhead/newlib/math/arithmetic.cljs
@@ -16,7 +16,7 @@
           th (thought/register-thought! [:EH :IO :RETURN]
                                         :data to
                                         :reference (str "<" to "+_>"))]
-      (del/add-delegate th [[:EH :PRIM :PARTIAL :+]])
+      (del/add-delegate th [:EH :PRIM :PARTIAL :+])
       (extend/register-extension! th [th])
       [parent th])))
 
@@ -28,7 +28,7 @@
           th (thought/register-thought! [:EH :IO :RETURN]
                                         :data [to from]
                                         :reference (str "<" to "+" from ">"))]
-      (del/add-delegate th [[:EH :LAZY [:EH :PRIM :NUM]]])
+      (del/add-delegate th [:EH :LAZY [:EH :PRIM :NUM]])
       (extend/register-extension! th [th])
       [parent th])))
 
@@ -39,7 +39,7 @@
           from (if (symbol? from) (msg/apply-msg to [:EH :REIFY]) from)]
       [parent (+ to from)])))
 
-(del/add-delegate [:EH :LAZY [:EH :PRIM :NUM]] [[:EH :PRIM :NUM]])
+(del/add-delegate [:EH :LAZY [:EH :PRIM :NUM]] [:EH :PRIM :NUM])
 
 (thought/register-singleton! [:EH :PRIM :PARTIAL :+ [:EH :PRIM :NUM]])
 (msg/register-single-impl [:EH :PRIM :PARTIAL :+] [:EH :PRIM :NUM] [:EH :PRIM :PARTIAL :+ [:EH :PRIM :NUM]])
diff --git a/src/cljs/emptyhead/newlib/scratch.cljs b/src/cljs/emptyhead/newlib/scratch.cljs
index 8b3d8b9..a73548c 100644
--- a/src/cljs/emptyhead/newlib/scratch.cljs
+++ b/src/cljs/emptyhead/newlib/scratch.cljs
@@ -8,4 +8,4 @@
             [emptyhead.newlib.math.number]))
 
 ;; XXX why does the second arg need to be wrapped like this?
-(del/add-delegate :! [[:EH :REIFY]])
+(del/add-delegate :! [:EH :REIFY])