diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+2.6.0 - 111211
+* added snapshot to all variants, which allows sampling signals within
+  signal generators
+
 2.5.0 - 111122
 * added SignalGen liftIO equivalent to assist library writers
 * simplified the signatures of effectful* combinators
diff --git a/FRP/Elerea/Clocked.hs b/FRP/Elerea/Clocked.hs
--- a/FRP/Elerea/Clocked.hs
+++ b/FRP/Elerea/Clocked.hs
@@ -73,6 +73,7 @@
     , externalMulti
     -- * Basic building blocks
     , delay
+    , snapshot
     , generator
     , memo
     , until
@@ -282,6 +283,16 @@
     let update x = s >>= \x' -> x' `seq` writeIORef ref (Updated x' x)
 
     addSignal return update ref pool
+
+-- | A formal conversion from signals to signal generators, which
+-- effectively allows for retrieving the current value of a previously
+-- created signal within a generator.  This includes both signals
+-- defined in an external scope as well as those created earlier in
+-- the same generator.  It can be modelled by the following function:
+--
+-- > snapshot s t_start s_clock = s t_start
+snapshot :: Signal a -> SignalGen a
+snapshot (S s) = SG $ \_ _ -> s
 
 -- | Auxiliary function.
 memoise :: IORef (Phase a) -> a -> IO a
diff --git a/FRP/Elerea/Param.hs b/FRP/Elerea/Param.hs
--- a/FRP/Elerea/Param.hs
+++ b/FRP/Elerea/Param.hs
@@ -22,6 +22,7 @@
     , externalMulti
     -- * Basic building blocks
     , delay
+    , snapshot
     , generator
     , memo
     , until
@@ -224,6 +225,16 @@
   let update x = s >>= \x' -> x' `seq` writeIORef ref (Updated x' x)
 
   addSignal return update ref pool
+
+-- | A formal conversion from signals to signal generators, which
+-- effectively allows for retrieving the current value of a previously
+-- created signal within a generator.  This includes both signals
+-- defined in an external scope as well as those created earlier in
+-- the same generator.  It can be modelled by the following function:
+--
+-- > snapshot s t_start s_input = s t_start
+snapshot :: Signal a -> SignalGen p a
+snapshot (S s) = SG $ \_ _ -> s
 
 -- | Auxiliary function.
 memoise :: IORef (Phase a) -> a -> IO a
diff --git a/FRP/Elerea/Simple.hs b/FRP/Elerea/Simple.hs
--- a/FRP/Elerea/Simple.hs
+++ b/FRP/Elerea/Simple.hs
@@ -18,6 +18,7 @@
     , externalMulti
     -- * Basic building blocks
     , delay
+    , snapshot
     , generator
     , memo
     , until
@@ -214,6 +215,15 @@
   let update x = s >>= \x' -> x' `seq` writeIORef ref (Updated x' x)
 
   addSignal return update ref pool
+
+-- | A formal conversion from signals to signal generators, which
+-- effectively allows for retrieving the current value of a previously
+-- created signal within a generator.  This includes both signals
+-- defined in an external scope as well as those created earlier in
+-- the same generator.  In the model, it corresponds to the identity
+-- function.
+snapshot :: Signal a -> SignalGen a
+snapshot (S s) = SG $ \_ -> s
 
 -- | Auxiliary function.
 memoise :: IORef (Phase a) -> a -> IO a
diff --git a/elerea.cabal b/elerea.cabal
--- a/elerea.cabal
+++ b/elerea.cabal
@@ -1,5 +1,5 @@
 Name:                elerea
-Version:             2.5.0
+Version:             2.6.0
 Cabal-Version:       >= 1.2
 Synopsis:            A minimalistic FRP library
 Category:            reactivity, FRP