diff --git a/docs/src/conf.py b/docs/src/conf.py
index 8bb359c..7fac303 100644
--- a/docs/src/conf.py
+++ b/docs/src/conf.py
@@ -42,7 +42,7 @@ imgmath_latex_preamble = r'''
     \end{tblr} }
 
 \newcommand{\gmrule}[2]
-    {\begin{tblr}{|rrrll|}
+    {\begin{tblr}{|rrrrll|}
          \hline
          & #1 \\
          \implies & #2 \\
diff --git a/docs/src/references/gm-state-transition-rules.rst b/docs/src/references/gm-state-transition-rules.rst
index 53485c1..42b8cac 100644
--- a/docs/src/references/gm-state-transition-rules.rst
+++ b/docs/src/references/gm-state-transition-rules.rst
@@ -12,6 +12,7 @@ Core Transition Rules
    \gmrule
    { \mathtt{PushGlobal} \; f : i
    & s
+   & d
    & h
    & m
    \begin{bmatrix}
@@ -20,6 +21,7 @@ Core Transition Rules
    }
    { i
    & a : s
+   & d
    & h
    & m
    }
@@ -31,11 +33,13 @@ Core Transition Rules
    \gmrule
    { \mathtt{PushInt} \; n : i
    & s
+   & d
    & h
    & m
    }
    { i
    & a : s
+   & d
    & h
    \begin{bmatrix}
         a : \mathtt{NNum} \; n
@@ -51,11 +55,13 @@ Core Transition Rules
    \gmrule
    { \mathtt{MkAp} : i
    & f : x : s
+   & d
    & h
    & m
    }
    { i
    & a : s
+   & d
    & h
    \begin{bmatrix}
         a : \mathtt{NAp} \; f \; x
@@ -69,11 +75,13 @@ Core Transition Rules
    \gmrule
    { \mathtt{Push} \; n : i
    & a_0 : \ldots : a_n : s
+   & d
    & h
    & m
    }
    { i
    & a_n : a_0 : \ldots : a_n : s
+   & d
    & h
    & m
    }
@@ -84,11 +92,13 @@ Core Transition Rules
    \gmrule
    { \mathtt{Slide} \; n : i
    & a_0 : \ldots : a_n : s
+   & d
    & h
    & m
    }
    { i
    & a_0 : s
+   & d
    & h
    & m
    }
@@ -100,6 +110,7 @@ Core Transition Rules
    \gmrule
    { \mathtt{Unwind} : \nillist
    & a : s
+   & d
    & h
    \begin{bmatrix}
         a : \mathtt{NNum} \; n
@@ -108,6 +119,7 @@ Core Transition Rules
    }
    { \nillist
    & a : s
+   & d
    & h
    & m
    }
@@ -118,6 +130,7 @@ Core Transition Rules
    \gmrule
    { \mathtt{Unwind} : \nillist
    & a : s
+   & d
    & h
    \begin{bmatrix}
         a : \mathtt{NAp} \; f \; x
@@ -126,6 +139,7 @@ Core Transition Rules
    }
    { \mathtt{Unwind} : \nillist
    & f : a : s
+   & d
    & h
    & m
    }
@@ -138,6 +152,7 @@ Core Transition Rules
    \gmrule
    { \mathtt{Unwind} : \nillist
    & a_0 : \ldots : a_n : s
+   & d
    & h
    \begin{bmatrix}
         a_0 : \mathtt{NGlobal} \; n \; c \\
@@ -149,6 +164,7 @@ Core Transition Rules
    }
    { c
    & e_1 : \ldots : e_n : a_n : s
+   & d
    & h
    & m
    }
@@ -159,6 +175,7 @@ Core Transition Rules
    \gmrule
    { \mathtt{Update} \; n : i
    & e : f : a_1 : \ldots : a_n : s
+   & d
    & h
    \begin{bmatrix}
         a_1 : \mathtt{NAp} \; f \; e \\
@@ -169,6 +186,7 @@ Core Transition Rules
    }
    { i
    & f : a_1 : \ldots : a_n : s
+   & d
    & h
    \begin{bmatrix}
         a_n : \mathtt{NInd} \; e
@@ -182,11 +200,13 @@ Core Transition Rules
    \gmrule
    { \mathtt{Pop} \; n : i
    & a_1 : \ldots : a_n : s
+   & d
    & h
    & m
    }
    { i
    & s
+   & d
    & h
    & m
    }
@@ -197,6 +217,7 @@ Core Transition Rules
    \gmrule
    { \mathtt{Unwind} : \nillist
    & a : s
+   & d
    & h
    \begin{bmatrix}
         a : \mathtt{NInd} \; a'
@@ -205,6 +226,7 @@ Core Transition Rules
    }
    { \mathtt{Unwind} : \nillist
    & a' : s
+   & d
    & h
    & m
    }
@@ -215,11 +237,13 @@ Core Transition Rules
    \gmrule
    { \mathtt{Alloc} \; n : i
    & s
+   & d
    & h
    & m
    }
    { i
    & a_1 : \ldots : a_n : s
+   & d
    & h
    \begin{bmatrix}
         a_1 : \mathtt{NUninitialised} \\
@@ -229,6 +253,43 @@ Core Transition Rules
    & m
    }
 
+13. When unwinding, if the top of the stack is in WHNF, pop the dump
+
+.. math::
+   \gmrule
+   { \mathtt{Unwind} : \nillist
+   & a : s
+   & \langle i', s' \rangle : d
+   & h
+   \begin{bmatrix}
+        a : \mathtt{NNum} \; n
+   \end{bmatrix}
+   & m
+   }
+   { i'
+   & a : s'
+   & d
+   & h
+   & m
+   }
+
+14. Evaluate the top of the stack to WHNF
+
+.. math::
+   \gmrule
+   { \mathtt{Eval} : i
+   & a : s
+   & d
+   & h
+   & m
+   }
+   { i
+   & a : \nillist
+   & \langle i, s \rangle
+   & h
+   & m
+   }
+
 ***************
 Extension Rules
 ***************
diff --git a/src/GM.hs b/src/GM.hs
index a45c252..a91bdfb 100644
--- a/src/GM.hs
+++ b/src/GM.hs
@@ -29,6 +29,7 @@ import Core
 data GmState = GmState
     { _gmCode   :: Code
     , _gmStack  :: Stack
+    , _gmDump   :: Dump
     , _gmHeap   :: GmHeap
     , _gmEnv    :: Env
     , _gmStats  :: Stats
@@ -37,6 +38,7 @@ data GmState = GmState
 
 type Code = [Instr]
 type Stack = [Addr]
+type Dump = [(Code, Stack)]
 type Env = [(Name, Addr)]
 type GmHeap = Heap Node
 
@@ -49,6 +51,9 @@ data Instr = Unwind
            | Update Int
            | Pop Int
            | Alloc Int
+           | Eval
+           | Add
+           | Mul
            deriving (Show, Eq)
 
 data Node = NNum Int
@@ -291,7 +296,7 @@ step st = case head (st ^. gmCode) of
 ----------------------------------------------------------------------------------
 
 compile :: Program -> GmState
-compile p = GmState c [] h g sts
+compile p = GmState c [] [] h g sts
     where
         -- find the entry point and start unwinding
         c = [PushGlobal "main", Unwind]
@@ -405,6 +410,8 @@ showState st = vcat
         , info $ showStack st
         , "-- Heap --------------------"
         , info $ showHeap st
+        , "-- Dump --------------------"
+        , info $ showDump st
         ]
     where
         stnum = st ^. (gmStats . stsReductions)
@@ -429,14 +436,35 @@ showStack st = vcat $ uncurry showEntry <$> si
         -- stack with labeled indices
         si = [0..] `zip` s
 
-        digitalWidth = length . show
-        maxWidth = digitalWidth $ maximum (addresses h)
-        showIndex n = pad <> int n <> ": "
-            where pad = text (replicate (maxWidth - digitalWidth n) ' ')
+        w = maxWidth (addresses h)
+        showIndex n = padInt w n <> ": "
 
         showEntry :: Int -> Addr -> Doc
         showEntry n a = showIndex n <> showNodeAt st a
 
+showDump :: GmState -> Doc
+showDump st = vcat $ uncurry showEntry <$> di
+    where
+        h = st ^. gmHeap
+        d = st ^. gmDump
+        di = [0..] `zip` d
+
+        showIndex n = padInt w n <> ": "
+        w = maxWidth (fst <$> di)
+
+        showEntry :: Int -> (Code, Stack) -> Doc
+        showEntry n (c,s) = showIndex n
+                         <> nest pprTabstop (showCode c)
+
+padInt :: Int -> Int -> Doc
+padInt m n = text (replicate (m - digitalWidth n) ' ') <> int n
+
+maxWidth :: [Int] -> Int
+maxWidth ns = digitalWidth $ maximum ns
+
+digitalWidth :: Int -> Int
+digitalWidth = length . show
+
 showHeap :: GmState -> Doc
 showHeap st = vcat $ showEntry <$> addresses h
     where
@@ -483,7 +511,7 @@ showCode c = "Code" <+> braces instrs
 showInstr :: Instr -> Doc
 showInstr i = text $ show i
 
-test = GmState c s h'' g sts
+test = GmState c s d h'' g sts
     where
         c = [Push 4, Push 5, Slide 2, Unwind]
         s = [a0,a1,a2]
@@ -492,5 +520,6 @@ test = GmState c s h'' g sts
         (h'',a2) = alloc h' $ NAp a0 a1
         g = [ ("f", a0)
             ]
+        d = []
         sts = def