diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+0.3.0 - 090419
+* documentation bug fixed: the latcher is not delayed
+* added dot (Graphviz) converter
+
 0.2.0 - 090412
 * removed primitives time and stateless
 * removed default delay on stateful combinators and added experimental cycle detection
diff --git a/FRP/Elerea.hs b/FRP/Elerea.hs
--- a/FRP/Elerea.hs
+++ b/FRP/Elerea.hs
@@ -48,10 +48,11 @@
 infixr 2 ||@
 
 {-| The `delay` transfer function emits the value of a signal from the
-previous superstep, starting with the filler value `v0`. -}
+previous superstep, starting with the filler value given in the first
+argument. -}
 
 delay :: a -> Signal a -> Signal a
-delay v0 s = snd <$> transfer (v0,undefined) (\_ v' (v,_) -> (v',v)) s
+delay v0 s = snd <$> transfer (v0,v0) (\_ v' (v,_) -> (v',v)) s
 
 {-| The `edge` transfer function takes a bool signal and emits another
 bool signal that turns true only at the moment when there is a rising
diff --git a/FRP/Elerea/Graph.hs b/FRP/Elerea/Graph.hs
new file mode 100644
--- /dev/null
+++ b/FRP/Elerea/Graph.hs
@@ -0,0 +1,154 @@
+{-# LANGUAGE ExistentialQuantification #-}
+{-# OPTIONS_GHC -fno-warn-name-shadowing #-}
+
+{-|
+
+This module provides some means to visualise the signal structure.
+
+-}
+
+module FRP.Elerea.Graph (signalToDot) where
+
+import Control.Monad
+import Data.IORef
+import Data.Maybe
+import qualified Data.Map as Map
+import Foreign.Ptr
+import Foreign.StablePtr
+import FRP.Elerea.Internal
+
+type Id = Int
+
+type SignalStore = Map.Map Id SignalInfo
+
+data SignalInfo
+    = Const
+    | Stateful
+    | Transfer Id
+    | App Id Id
+    | Latcher Id Id Id
+    | External
+    | Lift1 Id
+    | Lift2 Id Id
+    | Lift3 Id Id Id
+    | Lift4 Id Id Id Id
+    | Lift5 Id Id Id Id Id
+    | None
+
+getPtr :: a -> IO Id
+getPtr x = fmap (fromIntegral . ptrToIntPtr . castStablePtrToPtr) (newStablePtr x)
+
+buildStore :: SignalStore -> Signal a -> IO (Id,SignalStore)
+buildStore st (S r) = do
+  p <- getPtr r
+  case Map.lookup p st of
+    Just _  -> return (p,st)
+    Nothing -> do Ready s <- readIORef r  
+                  st' <- insertSignal st p s
+                  return (p,st')
+
+insertSignal :: SignalStore -> Id -> SignalNode a -> IO SignalStore
+insertSignal st p (SNK _) = return (Map.insert p Const st)
+insertSignal st p (SNS _ _) = return (Map.insert p Stateful st)
+insertSignal st p (SNT s _ _) = do
+  (s',st') <- buildStore (Map.insert p None st) s
+  return (Map.insert p (Transfer s') st')
+insertSignal st p (SNA sf sx) = do
+  (sf',st') <- buildStore (Map.insert p None st) sf
+  (sx',st'') <- buildStore st' sx
+  return (Map.insert p (App sf' sx') st'')
+insertSignal st p (SNE s e ss) = do
+  (s',st') <- buildStore (Map.insert p None st) s
+  (e',st'') <- buildStore st' e
+  (ss',st''') <- buildStore st'' ss
+  return (Map.insert p (Latcher s' e' ss') st''')
+insertSignal st p (SNR _) = return (Map.insert p External st)
+insertSignal st p (SNL1 _ s1) = do
+  (s1',st') <- buildStore (Map.insert p None st) s1
+  return (Map.insert p (Lift1 s1') st')
+insertSignal st p (SNL2 _ s1 s2) = do
+  (s1',st') <- buildStore (Map.insert p None st) s1
+  (s2',st'') <- buildStore st' s2
+  return (Map.insert p (Lift2 s1' s2') st'')
+insertSignal st p (SNL3 _ s1 s2 s3) = do
+  (s1',st') <- buildStore (Map.insert p None st) s1
+  (s2',st'') <- buildStore st' s2
+  (s3',st''') <- buildStore st'' s3
+  return (Map.insert p (Lift3 s1' s2' s3') st''')
+insertSignal st p (SNL4 _ s1 s2 s3 s4) = do
+  (s1',st') <- buildStore (Map.insert p None st) s1
+  (s2',st'') <- buildStore st' s2
+  (s3',st''') <- buildStore st'' s3
+  (s4',st'''') <- buildStore st''' s4
+  return (Map.insert p (Lift4 s1' s2' s3' s4') st'''')
+insertSignal st p (SNL5 _ s1 s2 s3 s4 s5) = do
+  (s1',st') <- buildStore (Map.insert p None st) s1
+  (s2',st'') <- buildStore st' s2
+  (s3',st''') <- buildStore st'' s3
+  (s4',st'''') <- buildStore st''' s4
+  (s5',st''''') <- buildStore st'''' s5
+  return (Map.insert p (Lift5 s1' s2' s3' s4' s5') st''''')
+
+nodeLabel :: Maybe Id -> SignalInfo -> [Char]
+nodeLabel id node = case node of
+                      Const           -> "const"
+                      Stateful        -> "stateful"
+                      Transfer _      -> "transfer"
+                      App _ _         -> "app"
+                      Latcher _ _ _   -> "latcher"
+                      External        -> "external"
+                      Lift1 _         -> "fun1"
+                      Lift2 _ _       -> "fun2"
+                      Lift3 _ _ _     -> "fun3"
+                      Lift4 _ _ _ _   -> "fun4"
+                      Lift5 _ _ _ _ _ -> "fun5"
+                      None            -> "NONE"
+                    ++ (maybe "" show id)
+
+{-|
+
+Traversing the network starting from the given signal and converting
+it into a string containing the graph in Graphviz
+(<http://www.graphviz.org/>) dot format.  Stateful nodes are coloured
+according to their type.
+
+Because of the fact that Elerea primitives are not referentially
+transparent, the results might differ depending on whether this
+function is called before or after sampling (this also affects the
+actual network!), but the networks should be still equivalent.
+
+-}
+
+signalToDot :: Signal a -> IO String
+signalToDot s = do
+  (_,st) <- buildStore Map.empty s
+  let rules = map mkRule (Map.assocs st)
+      mkRule (id,n) = "  " ++ name ++ attrs ++ edges
+          where name = nodeLabel (Just id) n
+                attrs = mkLabel (nodeLabel Nothing n) ("style=filled,fillcolor=\"#" ++ nodeCol ++ "\",shape=" ++ nodeShape)
+                edges = case n of
+                  Transfer s           -> mkEdge s "\"\""
+                  App sf sx            -> mkEdge sf "f" ++ mkEdge sx "x"
+                  Latcher s e ss       -> mkEdge s "init" ++ mkEdge e  "ctl" ++ mkEdge ss "\"\""
+                  Lift1 s1             -> mkEdge s1 "x1"
+                  Lift2 s1 s2          -> mkEdge s1 "x1" ++ mkEdge s2 "x2"
+                  Lift3 s1 s2 s3       -> mkEdge s1 "x1" ++ mkEdge s2 "x2" ++ mkEdge s3 "x3"
+                  Lift4 s1 s2 s3 s4    -> mkEdge s1 "x1" ++ mkEdge s2 "x2" ++ mkEdge s3 "x3" ++ mkEdge s4 "x4"
+                  Lift5 s1 s2 s3 s4 s5 -> mkEdge s1 "x1" ++ mkEdge s2 "x2" ++ mkEdge s3 "x3" ++ mkEdge s4 "x4" ++ mkEdge s5 "x5"
+                  _                    -> ""
+                mkEdge endId label = "  " ++ name ++ " -> " ++
+                                     nodeLabel (Just endId) (st Map.! endId) ++
+                                     mkLabel label "dir=back"
+                mkLabel name attrs = " [label=" ++ name ++ "," ++ attrs ++ "];\n"
+                nodeCol = case n of
+                  Transfer _    -> "ffcc99"
+                  Latcher _ _ _ -> "99ccff"
+                  External      -> "ccff99"
+                  Stateful      -> "ffffcc"
+                  _             -> "ffffff"
+                nodeShape = case n of
+                  Transfer _    -> "diamond"
+                  Latcher _ _ _ -> "hexagon"
+                  External      -> "invtriangle"
+                  _             -> "ellipse"
+  return $ "digraph G {\n" ++ concat rules ++ "}\n"
diff --git a/FRP/Elerea/Internal.hs b/FRP/Elerea/Internal.hs
--- a/FRP/Elerea/Internal.hs
+++ b/FRP/Elerea/Internal.hs
@@ -395,7 +395,9 @@
 
 {-| Reactive signal that starts out as @s@ and can change its
 behaviour to the one supplied in @ss@ whenever @e@ is true. The change
-can only be observed in the next instant. -}
+can be observed immediately, unless the signal is sampled by
+`sampleDelayed`, which puts a delay on the latch control (but not on
+the latched signal!). -}
 
 latcher :: Signal a          -- ^ @s@: initial behaviour
         -> Signal Bool       -- ^ @e@: latch control signal
diff --git a/elerea.cabal b/elerea.cabal
--- a/elerea.cabal
+++ b/elerea.cabal
@@ -1,5 +1,5 @@
 Name:                elerea
-Version:             0.2.0
+Version:             0.3.0
 Cabal-Version:       >= 1.2
 Synopsis:            A minimalistic FRP library
 Category:            reactivity, FRP
@@ -36,6 +36,7 @@
   Exposed-Modules:
     FRP.Elerea
     FRP.Elerea.Internal
+    FRP.Elerea.Graph
 
-  Build-Depends:       base
+  Build-Depends:       base, containers
   ghc-options:         -Wall -O2