diff --git a/CHANGELOG.md b/CHANGELOG.md
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+++ b/CHANGELOG.md
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+# Revision history for json-directory
+
+## 0.1.0.0 -- 2019-12-17
+
+* Initial version
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+Copyright (c) 2019, Luke Clifton
+
+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 Luke Clifton 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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+Provides utilities for reading JSON structures out of directories. Directory
+entries become keys in a map, and the values are sourced from the contets of
+each entry.
+
+ * Directories are recured into
+ * Files ending with `.json` are read as JSON values
+ * Everything else is interpreted as a string
+
+The [example](./example) directory in this repository would result in
+the following JSON value.
+
+```json
+{
+  "empty": {},
+  "a": "This is files will have its contents written into a JSON string.\n",
+  "d": {
+    "example": "Sometimes it's convenient to embed some raw JSON"
+  },
+  "b": 42,
+  "c": {
+    "nested": "You can nest directories to create a tree structure.\n"
+  }
+}
+```
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/json-directory.cabal b/json-directory.cabal
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--- /dev/null
+++ b/json-directory.cabal
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+cabal-version:       2.2
+
+name:                json-directory
+version:             0.1.0.0
+category:            Codec
+synopsis:            Load JSON from files in a directory structure
+description:         Load JSON from files in a directory structure. The object
+                     created mirrors the directory structure, using filenames
+                     as keys. Useful for breaking apart large JSON structures.
+bug-reports:         https://github.com/luke-clifton/json-directory/issues
+license:             BSD-3-Clause
+license-file:        LICENSE
+author:              Luke Clifton
+maintainer:          lukec@themk.net
+copyright:           (c) 2019 Luke Clifton
+extra-source-files:  CHANGELOG.md, README.md
+
+source-repository head
+  type: git
+  location: https://github.com/luke-clifton/json-directory
+
+library
+  exposed-modules:
+    Data.JSON.Directory
+  build-depends:       base ^>=4.12.0.0, aeson, directory, filepath, text, unordered-containers
+  hs-source-dirs:      src
+  default-language:    Haskell2010
+
+executable jsondir
+  build-depends:       base ^>=4.12.0.0, json-directory, bytestring, aeson
+  hs-source-dirs:      jsondir
+  default-language:    Haskell2010
+  main-is: Main.hs
+  
diff --git a/jsondir/Main.hs b/jsondir/Main.hs
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--- /dev/null
+++ b/jsondir/Main.hs
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+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE BlockArguments #-}
+module Main where
+
+import Data.Aeson
+import Control.Monad
+import System.Environment
+import Data.JSON.Directory
+import qualified Data.ByteString.Lazy.Char8 as B
+
+main :: IO ()
+main = do
+    as <- getArgs
+    forM_ as \a -> do
+        decodeDirectory @Value a >>= \case
+            Left e -> error e
+            Right v -> B.putStrLn $ encode v
+
diff --git a/src/Data/JSON/Directory.hs b/src/Data/JSON/Directory.hs
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--- /dev/null
+++ b/src/Data/JSON/Directory.hs
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+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE BlockArguments #-}
+module Data.JSON.Directory
+    ( decodeDirectory
+    , ModifiedWhileReading
+    ) where
+
+import Control.Exception
+import Control.Monad
+import Control.Monad.IO.Class
+import Data.Aeson
+import Data.HashMap.Strict
+import Data.List
+import Data.Maybe
+import Data.Text (Text)
+import qualified Data.Text as Text
+import qualified Data.Text.IO as Text
+import System.Directory
+import System.FilePath
+
+data ModifiedWhileReading = ModifiedWhileReading FilePath
+    deriving (Show)
+
+instance Exception ModifiedWhileReading
+
+data EntryType
+    = Directory
+    | JSON
+    | TextFile
+
+pathType :: FilePath -> IO (Text, EntryType)
+pathType p = do
+    doesDirectoryExist p >>= \case
+        True -> pure (Text.pack $ takeFileName p, Directory)
+        False -> pure case splitExtension (takeFileName p) of
+            (name, ".json") -> (Text.pack $ name, JSON)
+            _               -> (Text.pack $ takeFileName p, TextFile)
+
+decodeDirectoryValue :: MonadIO io => FilePath -> io (Either String Value)
+decodeDirectoryValue path = liftIO $ do
+    time <- getModificationTime path
+    ents <- listDirectory path
+    kvs <- catMaybes <$> forM ents \ent -> do
+        if "." `isPrefixOf` ent
+        then pure Nothing
+        else Just <$> do
+            let path' = path </> ent
+            pathType path' >>= \case
+                (n, Directory) -> (n,) <$> decodeDirectoryValue path'
+                (n, JSON     ) -> (n,) <$> eitherDecodeFileStrict path'
+                (n, TextFile ) -> (n,) . Right . String <$> Text.readFile path'
+    time2 <- getModificationTime path
+    unless (time == time2) $ throwIO (ModifiedWhileReading path)
+
+    pure $ Object <$> sequence (Data.HashMap.Strict.fromList kvs)
+
+resultToEither :: Result a -> Either String a
+resultToEither (Success a) = Right a
+resultToEither (Error s)   = Left s
+
+-- | Takes a directory and decodes it using a @`FromJSON`@ instance.
+-- Each entry in the directory becomes a key, and the contents become
+-- the corresponding value.
+--
+-- * Directories are recursed into.
+-- * Files ending in @.json@ are decoded as JSON values.
+-- * Everything else is assumed to be a valid unicode string.
+--
+-- This function can throw IO exceptions as well as a @`ModifiedWhileReading`@
+-- exception if the modification time changes during processing.
+decodeDirectory :: (FromJSON a, MonadIO io) => FilePath -> io (Either String a)
+decodeDirectory p = do
+    ev <- decodeDirectoryValue p
+    pure $ do
+        v <- ev
+        resultToEither $ fromJSON v