diff --git a/CHANGELOG.md b/CHANGELOG.md
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+++ b/CHANGELOG.md
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+# Revision history for database-id-groundhog
+
+## 0.1.0.1
+
+* Add readme
+
+## 0.1.0.0
+
+* Initial release. Defines the DefaultKeyId class, connecting groundhog IDs to HasId instances, and some convenience functions for going back and forth between the two.
+* Add PersistField instances handy for storing `Id`s in the database (e.g., as foreign keys).
+* Add Template Haskell for generating IdData and DefaultKeyId instances
diff --git a/LICENSE b/LICENSE
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+++ b/LICENSE
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+Copyright (c) 2019, Obsidian Systems LLC
+
+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 Obsidian Systems LLC 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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+++ b/README.md
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+database-id-groundhog
+---------------------
+
+This package provides support for groundhog database interaction to database-id-class, in particular, the functions
+
+    toId :: DefaultKeyId a => DefaultKey a -> Id a
+    fromId :: DefaultKeyId a => Id a -> DefaultKey a
+
+which convert back and forth between the Id and groundhog's DefaultKey representation according to the instances of
+the `DefaultKeyId` class.
+
+It also includes the Template Haskell macro `makeDefaultKeyIdInt64` which, given the `Name` of a datatype and the `Name` of
+the data constructor for its groundhog-generated key datatype (typically named the same as the type, with the suffix
+"Key"), produces an instance of DefaultKeyId in cases where the primary key is an `Int64`.
+
+Similar to this, `makeDefaultKeyIdSimple` exists for cases where all that is required to go between `DefaultKey a` and
+`IdData a` is to remove (or put back) Groundhog's type-specific Key data constructor.
+
+It also includes instances of `PersistField` and `PrimitivePersistField` for `Id a`.
diff --git a/Setup.hs b/Setup.hs
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+++ b/Setup.hs
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+import Distribution.Simple
+main = defaultMain
diff --git a/database-id-groundhog.cabal b/database-id-groundhog.cabal
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+++ b/database-id-groundhog.cabal
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+cabal-version:       >=1.10
+name:                database-id-groundhog
+version:             0.1.0.1
+synopsis:            HasId/Groundhog interop
+description:         A class and some instances for HasId/Groundhog interoperation
+license:             BSD3
+license-file:        LICENSE
+author:              Obsidian Systems LLC
+maintainer:          maintainer@obsidian.systems
+copyright:           2019 Obsidian Systems LLC
+category:            Database
+build-type:          Simple
+extra-source-files: CHANGELOG.md
+                    README.md
+
+library
+  exposed-modules: Database.Id.Groundhog
+                 , Database.Id.Groundhog.TH
+  other-extensions: QuasiQuotes
+                  , TemplateHaskell
+  build-depends: base >=4.11 && <4.13
+               , aeson
+               , database-id-class
+               , groundhog <= 0.7.0.3
+               , template-haskell
+  hs-source-dirs:      src
+  default-language:    Haskell2010
diff --git a/src/Database/Id/Groundhog.hs b/src/Database/Id/Groundhog.hs
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+++ b/src/Database/Id/Groundhog.hs
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+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE StandaloneDeriving #-}
+{-# LANGUAGE UndecidableInstances #-}
+module Database.Id.Groundhog where
+
+import Data.Proxy
+import Database.Groundhog.Core
+import Database.Id.Class
+
+class HasId a => DefaultKeyId a where
+  toIdData :: Proxy a -> DefaultKey a -> IdData a
+  fromIdData :: Proxy a -> IdData a -> DefaultKey a
+
+toId :: forall a. DefaultKeyId a => DefaultKey a -> Id a
+toId = Id . toIdData (Proxy :: Proxy a)
+
+fromId :: forall a. DefaultKeyId a => Id a -> DefaultKey a
+fromId = fromIdData (Proxy :: Proxy a) . unId
+
+deriving instance NeverNull (IdData a) => NeverNull (Id a) -- A redundant constraint warning is expected here
+
+instance (PersistField (DefaultKey a), DefaultKeyId a) => PersistField (Id a) where
+  persistName = persistName
+  toPersistValues = toPersistValues . fromId
+  fromPersistValues vs = do
+    (a, vs') <- fromPersistValues vs
+    return (toId a, vs')
+  dbType p _ = dbType p (undefined :: DefaultKey a)
+
+instance (PrimitivePersistField (DefaultKey a), DefaultKeyId a) => PrimitivePersistField (Id a) where
+  toPrimitivePersistValue p = toPrimitivePersistValue p . fromId
+  fromPrimitivePersistValue p = toId . fromPrimitivePersistValue p
+
+type IdDataIs a b = IdData a ~ b
diff --git a/src/Database/Id/Groundhog/TH.hs b/src/Database/Id/Groundhog/TH.hs
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+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE TemplateHaskell #-}
+
+module Database.Id.Groundhog.TH where
+
+import Data.Int
+import Database.Id.Groundhog
+import Database.Groundhog.Core
+import Language.Haskell.TH
+
+makeDefaultKeyIdInt64 :: Name -> Name -> Q [Dec]
+makeDefaultKeyIdInt64 n k = do
+  pv <- newName "pv"
+  [d|
+    instance IdDataIs $(conT n) Int64 => DefaultKeyId $(conT n) where
+      toIdData _ dk = case $(lamE [conP k [varP pv]] (varE pv)) dk of
+        PersistInt64 x -> x
+        _ -> error "makeDefaultKeyIdInt64: pattern match failure (this should be impossible)"
+      fromIdData _ = $(conE k) . PersistInt64
+    |]
+
+makeDefaultKeyIdSimple :: Name -> Name -> Q [Dec]
+makeDefaultKeyIdSimple n k = do
+  pv <- newName "pv"
+  [d|
+    instance DefaultKeyId $(conT n) where
+      toIdData _ = $(lamE [conP k [varP pv]] (varE pv))
+      fromIdData _ = $(conE k)
+    |]