diff --git a/System/Random/MWC/Monad.hs b/System/Random/MWC/Monad.hs
--- a/System/Random/MWC/Monad.hs
+++ b/System/Random/MWC/Monad.hs
@@ -1,5 +1,7 @@
+{-# LANGUAGE FlexibleContexts #-}
 module System.Random.MWC.Monad ( -- * Random monad
                                  Rand
+                               , liftR
                                , RandIO
                                , asRandIO
                                , RandST
@@ -15,6 +17,9 @@
                                , uniformR
                                , standard
                                , normal
+                                 -- * Combining monads 
+                               , equiprobable
+                               , choices
                                  -- * Seed management
                                , save
                                ) where
@@ -24,8 +29,12 @@
 import Control.Monad.ST        (ST)
 import Control.Monad.Primitive (PrimMonad, PrimState)
 
-import Data.Vector.Unboxed (Vector)
+import qualified Data.Vector         as V
+import qualified Data.Vector.Unboxed as U
+import qualified Data.Vector.Generic as G
+import Data.Ord
 import Data.Word           (Word32)
+import Debug.Trace
 
 import qualified System.Random.MWC as MWC
 import           System.Random.MWC   (Gen,Variate,Seed)
@@ -38,6 +47,11 @@
   runRand :: Gen (PrimState m) -> m a
   }
 
+-- | Lift monadic action into 'Rand' monad
+liftR :: PrimMonad m => m a -> Rand m a
+liftR m = Rand $ const m
+{-# INLINE liftR #-}
+
 -- | Type synonim for ST-based Rand monad
 type RandST s a = Rand (ST s) a
 
@@ -60,7 +74,7 @@
 {-# INLINE runWithCreate #-}
 
 -- | By creating seed from vector of values
-runWithVector :: PrimMonad m => Rand m a -> Vector Word32 -> m a
+runWithVector :: (G.Vector v Word32, PrimMonad m) => Rand m a -> v Word32 -> m a
 runWithVector m v = runRand m =<< MWC.initialize v
 {-# INLINE runWithVector #-}
 
@@ -119,6 +133,55 @@
        -> Rand m Double
 normal m s = (+ m) . (* s) <$> standard
 {-# INLINE standard #-}
+
+----------------------------------------------------------------
+
+-- | Randomly select from list of equiprobable random sources. List must be non-empty
+equiprobable :: PrimMonad m => [Rand m a] -> Rand m a
+equiprobable [] = error "System.Random.MWC.Monad.equiprobable: list must be nonempty"
+equiprobable xs = worker (V.fromList xs)
+  where
+    worker v = do
+      -- uniform - 2^(-53) lies in the [0,1) range
+      p <- uniform
+      v V.! truncate ((p - 2^^(-53)) * fromIntegral (V.length v) :: Double)
+      
+-- | Randomly select from list of weighted random sources. List must
+-- contain sources with positive weight. Elements with non-positive
+-- weight are discarded
+choices :: PrimMonad m => [(Double,Rand m a)] -> Rand m a
+choices xs
+  | null xs'  = error "System.Random.MWC.Monad.choices: list must contain at least one nonnegative weight"
+  | otherwise = traceShow (ps, V.length vect) 
+                $ worker vect ps
+  where
+    xs'  = filter ((>0) . fst) xs
+    vect = V.fromList (map snd xs')
+    ps   = U.init . U.scanl' (+) 0 $ U.map (/ U.sum q) q
+           where q = U.fromList (map fst xs')
+    worker vect probs = do
+      p <- uniform
+      let i = binary probs p
+      vect V.! (i - 1)
+
+-- Binary search /Copied from vector algorithms
+binary :: (Ord a, U.Unbox a) => U.Vector a -> a -> Int
+binary v x = binaryRange v x 0 (U.length v)
+{-# INLINE binary #-}
+
+-- Binary search in range
+binaryRange :: (Ord a, U.Unbox a) => U.Vector a -> a -> Int -> Int -> Int
+binaryRange v x = loop 
+  where
+    loop i j | i >= j    = j
+             | otherwise = case compare (U.unsafeIndex v k) x of
+                             LT -> loop (k+1) j
+                             EQ -> k  
+                             GT -> loop i k
+             where k = (i + j) `div` 2
+{-# INLINE binaryRange #-}
+
+
 
 ----------------------------------------------------------------
 
diff --git a/mwc-random-monad.cabal b/mwc-random-monad.cabal
--- a/mwc-random-monad.cabal
+++ b/mwc-random-monad.cabal
@@ -1,5 +1,5 @@
 Name:                mwc-random-monad
-Version:             0.1
+Version:             0.2
 Synopsis:            Monadic interface for mwc-random
 License:             BSD3
 License-file:        LICENSE