diff --git a/random-source.cabal b/random-source.cabal
--- a/random-source.cabal
+++ b/random-source.cabal
@@ -1,5 +1,5 @@
 name:                   random-source
-version:                0.3.0.6
+version:                0.3.0.8
 stability:              provisional
 
 cabal-version:          >= 1.6
@@ -85,7 +85,8 @@
                         random,
                         stateref >= 0.3 && < 0.4,
                         template-haskell,
-                        th-extras
+                        th-extras,
+                        primitive
 
   if os(Windows)
     cpp-options:        -Dwindows
diff --git a/src/Data/Random/Source/Internal/TH.hs b/src/Data/Random/Source/Internal/TH.hs
--- a/src/Data/Random/Source/Internal/TH.hs
+++ b/src/Data/Random/Source/Internal/TH.hs
@@ -81,17 +81,9 @@
     c <- ask
     mapReaderT (FD.function (methodNameBase c m)) f
 
-requireMethod :: Method -> ReaderT Context (FD.Defaults s) ()
-requireMethod m = do
-    c <- ask
-    lift (FD.requireFunction (methodNameBase c m))
-
 implementation :: ReaderT Context (FD.Implementation s) (Q [Dec]) -> ReaderT Context (FD.Function s) ()
 implementation = mapReaderT FD.implementation
 
-score :: s -> ReaderT Context (FD.Implementation s) ()
-score = lift . FD.score
-
 cost :: Num s => s -> ReaderT Context (FD.Implementation s) ()
 cost = lift . FD.cost
 
@@ -99,15 +91,6 @@
 dependsOn m = do
     c <- ask
     lift (FD.dependsOn (methodNameBase c m))
-
-inline :: ReaderT Context (FD.Implementation s) ()
-inline = lift FD.inline
-
-noinline :: ReaderT Context (FD.Implementation s) ()
-noinline = lift FD.noinline
-
-replaceMethodName :: (Method -> Name) -> Name -> Name
-replaceMethodName f = replace (fmap f . nameToMethod Generic)
 
 changeContext :: Context -> Context -> Name -> Name
 changeContext c1 c2 = replace (fmap (methodName c2) . nameToMethod c1)
diff --git a/src/Data/Random/Source/MWC.hs b/src/Data/Random/Source/MWC.hs
--- a/src/Data/Random/Source/MWC.hs
+++ b/src/Data/Random/Source/MWC.hs
@@ -19,6 +19,8 @@
 import Data.Random.Source
 import System.Random.MWC
 import Control.Monad.ST
+import Control.Monad.Reader
+import Control.Monad.Primitive
 
 $(randomSource
     [d| instance RandomSource (ST s) (Gen s) where
@@ -37,3 +39,10 @@
             getRandomWord64From = uniform
             getRandomDoubleFrom = fmap wordToDouble . uniform
      |])
+
+$(monadRandom [d|
+  instance (PrimMonad m, s ~ PrimState m) => MonadRandom (ReaderT (Gen s) m) where
+    getRandomWord16 = ask >>= lift . uniform
+    getRandomWord32 = ask >>= lift . uniform
+    getRandomWord64 = ask >>= lift . uniform
+  |])
diff --git a/src/Data/Random/Source/PureMT.hs b/src/Data/Random/Source/PureMT.hs
--- a/src/Data/Random/Source/PureMT.hs
+++ b/src/Data/Random/Source/PureMT.hs
@@ -25,7 +25,9 @@
     ) where
 
 import Control.Monad.State
+import Control.Monad.RWS
 import qualified Control.Monad.State.Strict as S
+import qualified Control.Monad.RWS.Strict as S
 import Data.Random.Internal.Source
 import Data.Random.Source.Internal.TH
 import Data.StateRef
@@ -58,6 +60,18 @@
             getRandomDouble = withMTState randomDouble
      |])
 
+$(monadRandom
+    [d| instance Monoid w => MonadRandom (RWS r w PureMT) where
+            getRandomWord64 = withMTState randomWord64
+            getRandomDouble = withMTState randomDouble
+     |])
+
+$(monadRandom
+    [d| instance Monoid w => MonadRandom (S.RWS r w PureMT) where
+            getRandomWord64 = withMTState randomWord64
+            getRandomDouble = withMTState randomDouble
+     |])
+
 #endif
 
 $(randomSource
@@ -74,6 +88,18 @@
 
 $(monadRandom
     [d| instance Monad m => MonadRandom (S.StateT PureMT m) where
+            getRandomWord64 = withMTState randomWord64
+            getRandomDouble = withMTState randomDouble
+     |])
+
+$(monadRandom
+    [d| instance (Monad m, Monoid w) => MonadRandom (RWST r w PureMT m) where
+            getRandomWord64 = withMTState randomWord64
+            getRandomDouble = withMTState randomDouble
+     |])
+
+$(monadRandom
+    [d| instance (Monad m, Monoid w) => MonadRandom (S.RWST r w PureMT m) where
             getRandomWord64 = withMTState randomWord64
             getRandomDouble = withMTState randomDouble
      |])
diff --git a/src/Data/Random/Source/StdGen.hs b/src/Data/Random/Source/StdGen.hs
--- a/src/Data/Random/Source/StdGen.hs
+++ b/src/Data/Random/Source/StdGen.hs
@@ -24,8 +24,10 @@
 import Data.Random.Internal.Source
 import System.Random
 import Control.Monad.State
+import Control.Monad.RWS
 import qualified Control.Monad.ST.Strict as S
 import qualified Control.Monad.State.Strict as S
+import qualified Control.Monad.RWS.Strict as S
 import Data.StateRef
 import Data.Word
 
@@ -119,6 +121,12 @@
 
 instance MonadRandom (S.State StdGen) where
     getRandomPrim = getRandomPrimFromRandomGenState
+
+instance Monoid w => MonadRandom (RWS r w StdGen) where
+    getRandomPrim = getRandomPrimFromRandomGenState
+
+instance Monoid w => MonadRandom (S.RWS r w StdGen) where
+    getRandomPrim = getRandomPrimFromRandomGenState
 #endif
 
 instance Monad m => MonadRandom (StateT StdGen m) where
@@ -127,3 +135,8 @@
 instance Monad m => MonadRandom (S.StateT StdGen m) where
     getRandomPrim = getRandomPrimFromRandomGenState
 
+instance (Monad m, Monoid w) => MonadRandom (RWST r w StdGen m) where
+    getRandomPrim = getRandomPrimFromRandomGenState
+
+instance (Monad m, Monoid w) => MonadRandom (S.RWST r w StdGen m) where
+    getRandomPrim = getRandomPrimFromRandomGenState