diff --git a/ChangeLog.md b/ChangeLog.md
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+++ b/ChangeLog.md
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+# Changelog for multipool
+
+## Unreleased changes
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+Copyright Author name here (c) 2018
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Author name here nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
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--- /dev/null
+++ b/README.md
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+# multipool
diff --git a/Setup.hs b/Setup.hs
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--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/multipool.cabal b/multipool.cabal
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--- /dev/null
+++ b/multipool.cabal
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+-- This file has been generated from package.yaml by hpack version 0.28.2.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: 94867a7572b048dffde7b9f36b385a6ca96a42467c6d513f22a25f60ed82c231
+
+name:           multipool
+version:        0.1.0.0
+synopsis:       Generalized system for reading and writing to distributed systems that have primary/replica topologies.
+description:    Please see the README on GitHub at <https://github.com/githubuser/multipool#readme>
+homepage:       https://github.com/iand675/multipool#readme
+bug-reports:    https://github.com/iand675/multipool/issues
+author:         Ian Duncan
+maintainer:     ian@iankduncan.com
+copyright:      2018 Ian Duncan
+license:        BSD3
+license-file:   LICENSE
+build-type:     Simple
+cabal-version:  >= 1.10
+extra-source-files:
+    ChangeLog.md
+    README.md
+
+source-repository head
+  type: git
+  location: https://github.com/iand675/multipool
+
+library
+  exposed-modules:
+      Data.MultiPool
+  other-modules:
+      Paths_multipool
+  hs-source-dirs:
+      src
+  build-depends:
+      base >=4.7 && <5
+    , bytestring
+    , hashable
+    , hedis
+    , mmorph
+    , monad-logger
+    , mtl
+    , persistent
+    , persistent-postgresql
+    , postgresql-common-persistent
+    , resource-pool
+    , text
+    , unordered-containers
+  default-language: Haskell2010
+
+test-suite multipool-test
+  type: exitcode-stdio-1.0
+  main-is: Spec.hs
+  other-modules:
+      Paths_multipool
+  hs-source-dirs:
+      test
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      base >=4.7 && <5
+    , bytestring
+    , hashable
+    , hedis
+    , mmorph
+    , monad-logger
+    , mtl
+    , multipool
+    , persistent
+    , persistent-postgresql
+    , postgresql-common-persistent
+    , resource-pool
+    , text
+    , unordered-containers
+  default-language: Haskell2010
diff --git a/src/Data/MultiPool.hs b/src/Data/MultiPool.hs
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--- /dev/null
+++ b/src/Data/MultiPool.hs
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+{-# LANGUAGE AllowAmbiguousTypes #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE RecordWildCards #-}
+
+module Data.MultiPool where
+
+import Control.Exception
+import Control.Monad.Reader
+import Control.Monad.Logger
+import Data.Hashable
+import Data.HashMap.Strict (HashMap)
+import qualified Data.HashMap.Strict as HM
+import Data.Pool
+import Data.Text (Text)
+import Data.Text.Encoding
+import Data.Typeable
+import Data.IORef
+-- Todo: separate out implementations
+import Data.ByteString (ByteString)
+import Database.Persist.Postgresql
+import Database.Persist.Postgresql.Common
+
+newtype InstanceName backend = InstanceName
+  { rawInstanceName :: Hashed Text
+  } deriving (Show, Eq, Ord)
+
+mkInstanceName :: Text -> InstanceName backend
+mkInstanceName = InstanceName . hashed
+
+instance Hashable (InstanceName backend) where
+  hashWithSalt s r = hashWithSalt s (rawInstanceName r)
+  hash = hash . rawInstanceName
+
+data InstanceDoesNotExist backend = InstanceDoesNotExist
+  { instanceDoesNotExist :: InstanceName backend
+  } deriving (Show, Eq, Typeable)
+
+instance (Show (InstanceDoesNotExist backend), Typeable backend) => Exception (InstanceDoesNotExist backend)
+
+class Monad m => MultiPoolBackend m backend where
+  type Masters backend :: *
+  type Masters backend = Pool (MasterConnection backend)
+  type Replicas backend :: *
+  type Replicas backend = HashMap (ReplicaIdentifier backend) (Pool (ReplicaConnection backend))
+
+  type MasterConnection backend :: *
+  type ReplicaConnection backend :: *
+
+  type MasterIdentifier backend :: *
+  type MasterIdentifier backend = ()
+  type ReplicaIdentifier backend :: *
+  type ReplicaIdentifier backend = InstanceName backend
+
+  runWriteAny :: MultiPool backend -> ReaderT (MasterConnection backend) m a -> m a
+  runWrite :: MultiPool backend -> MasterIdentifier backend -> ReaderT (MasterConnection backend) m a -> m a
+
+  runReadMaster :: MultiPool backend -> MasterIdentifier backend -> ReaderT (ReplicaConnection backend) m a -> m a
+  runReadAnyMaster :: MultiPool backend -> ReaderT (ReplicaConnection backend) m a -> m a
+  runReadAny :: MultiPool backend -> ReaderT (ReplicaConnection backend) m a -> m a
+  runRead :: MultiPool backend -> ReplicaIdentifier backend -> ReaderT (ReplicaConnection backend) m a -> m a
+
+
+-- Invariant: MultiPool should not be modified after creation?
+data MultiPool backend = MultiPool
+  { multiPoolMaster :: !(Masters backend)
+  , multiPoolReplica :: !(Replicas backend)
+  , multiPoolAnyMasterSelector :: MultiPool backend -> IO (MasterIdentifier backend)
+  , multiPoolAnyReplicaSelector :: MultiPool backend -> IO (Maybe (ReplicaIdentifier backend))
+  }
+
+forReplicas :: (MultiPoolBackend m backend, Replicas backend ~ HashMap k v) => MultiPool backend -> (k -> v -> m a) -> m [a]
+forReplicas pool f = forM (HM.toList (multiPoolReplica pool)) $ \(k, v) -> f k v
+
+roundRobin :: MonadIO m => [choice] -> m (a -> IO (Maybe choice))
+roundRobin [] = return $ const $ return Nothing
+roundRobin choices = do
+  let infiniteChoice = cycle choices
+  picker <- liftIO $ newIORef infiniteChoice
+  return $ const $ atomicModifyIORef' picker $ \l -> case l of
+    (x:xs) -> (xs, Just x)
+    [] -> error "roundRobin: should have matched empty list in first clause"
diff --git a/test/Spec.hs b/test/Spec.hs
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--- /dev/null
+++ b/test/Spec.hs
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+main :: IO ()
+main = putStrLn "Test suite not yet implemented"