diff --git a/data-forest.cabal b/data-forest.cabal
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--- /dev/null
+++ b/data-forest.cabal
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+-- This file has been generated from package.yaml by hpack version 0.17.0.
+--
+-- see: https://github.com/sol/hpack
+
+name:           data-forest
+version:        0.1.0.0
+synopsis:       A simple multi-way tree data structure.
+
+description:    In some contexts, /forests/ are more important than /trees/. The /forest/ library provides a @Tree@ type much like the one from the popular /containers/ library, but it also provides a @Forest@ type with its own @Functor@ and @Foldable@ instances.
+category:       Data Structures
+homepage:       https://github.com/chris-martin/haskell-libraries
+author:         Chris Martin <ch.martin@gmail.com>
+maintainer:     Chris Martin <ch.martin@gmail.com>
+license:        Apache-2.0
+license-file:   license.txt
+build-type:     Simple
+cabal-version:  >= 1.10
+
+library
+  hs-source-dirs:
+      src
+  default-extensions: NoImplicitPrelude
+  ghc-options: -Wall
+  build-depends:
+      base >= 4.9 && < 4.10
+  exposed-modules:
+      Data.Forest
+  other-modules:
+      Paths_data_forest
+  default-language: Haskell2010
+
+test-suite doctest
+  type: exitcode-stdio-1.0
+  main-is: doctest.hs
+  hs-source-dirs:
+      test
+  default-extensions: NoImplicitPrelude
+  ghc-options: -Wall
+  build-depends:
+      base >= 4.9 && < 4.10
+    , doctest
+    , forest
+  default-language: Haskell2010
diff --git a/license.txt b/license.txt
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--- /dev/null
+++ b/license.txt
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+Copyright 2017 Chris Martin
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
diff --git a/src/Data/Forest.hs b/src/Data/Forest.hs
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--- /dev/null
+++ b/src/Data/Forest.hs
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+{- |
+
+Multi-way trees (also known as /rose trees/) and forests, similar to @Data.Tree@
+from the popular /containers/ library.
+
+-}
+
+{-# LANGUAGE DeriveFoldable, DeriveFunctor, GeneralizedNewtypeDeriving #-}
+
+module Data.Forest
+    (
+    -- * Importing
+    -- $imports
+
+    -- * Types
+      Forest
+    , Tree
+
+    -- * Constructing
+    , forest
+    , tree
+    , leaf
+    , leaves
+
+    -- * Deconstructing
+    , trees
+    , root
+    , subforest
+    , subtrees
+
+    -- * Forest functor
+    -- $functor
+
+    ) where
+
+import Data.Eq (Eq)
+import Data.Foldable (Foldable)
+import Data.Functor (Functor, fmap)
+import Data.Monoid (Monoid, mempty)
+import Data.Semigroup (Semigroup)
+import Prelude (Show)
+
+--------------------------------------------------------------------------------
+
+-- | A forest is defined completely by its 'trees'.
+--
+-- To construct a forest, use 'forest' or 'leaves'.
+
+newtype Forest a = Forest
+    { trees :: [Tree a] -- ^ The trees that constitute the forest.
+    }
+    deriving (Eq, Show, Foldable, Functor, Semigroup, Monoid)
+
+-- | A tree is defined completely by its 'root' and its 'subforest'.
+--
+-- To construct a tree, use 'tree' or 'leaf'.
+
+data Tree a = Tree
+    { root :: a             -- ^ The value at the root node of the tree.
+    , subforest :: Forest a -- ^ The forest containing all descendants
+                            --   of the tree's 'root'.
+    }
+    deriving (Eq, Show, Foldable, Functor)
+
+--------------------------------------------------------------------------------
+
+-- | Construct a forest from a list of trees.
+--
+-- /@'forest' []@ is equivalent to 'mempty'./
+forest :: [Tree a] -> Forest a
+forest = Forest
+
+-- | Construct a tree with a single root and no subforest.
+--
+--   /@'leaf' x@ is equivalent to @'tree' x 'mempty'@./
+leaf :: a -> Tree a
+leaf a = tree a mempty
+
+-- | Construct a forest of depth 1, where each tree contains only a root.
+--
+-- /'leaves' is equivalent to @'forest' . fmap 'leaf'@/
+leaves :: [a] -> Forest a
+leaves xs =
+  forest (fmap leaf xs)
+
+-- | Construct a tree with a root and subforest.
+tree :: a -> Forest a -> Tree a
+tree = Tree
+
+-- | The tree's immediate subtrees.
+--
+-- /'subtrees' is equivalent to @'trees' . 'subforest'@./
+subtrees :: Tree a -> [Tree a]
+subtrees t = trees (subforest t)
+
+--------------------------------------------------------------------------------
+
+{- $setup
+
+>>> import Prelude
+>>> import Data.Char
+>>> import Data.Foldable
+>>> import Data.List
+>>> import Data.Semigroup
+
+-}
+
+--------------------------------------------------------------------------------
+
+{- $imports
+
+Recommended imports:
+
+> import Data.Forest (Forest, Tree)
+> import qualified Data.Forest as Forest
+
+-}
+
+--------------------------------------------------------------------------------
+
+{- $functor
+
+One notable difference of this 'Forest' from that of the /containers/ library is
+that this 'Forest' is a newtype rather than a type alias, and so it provides a
+more appropriate 'Functor' instance:
+
+>>>
+:{
+example :: Forest Char
+example = forest
+    [ tree 'a' $ leaves "bc"
+    , tree 'd' $ forest
+        [ leaf 'e'
+        , tree 'f' $ leaves "g"
+        ]
+   ]
+:}
+
+>>>
+:{
+printCharForest = putStrLn . showForest
+  where
+    showForest f = intercalate ", " (fmap showTree (trees f))
+    showTree t = case trees (subforest t) of
+        []   -> [root t]
+        [t'] -> [root t] <> ": " <> showTree t'
+        ts   -> [root t] <> ": (" <> showForest (subforest t) <> ")"
+:}
+
+>>> printCharForest example
+a: (b, c), d: (e, f: g)
+
+>>> printCharForest (fmap toUpper example)
+A: (B, C), D: (E, F: G)
+
+Likewise, 'Forest''s 'Foldable' instance folds over the elements of the forest.
+
+>>> toList example
+"abcdefg"
+
+-}
diff --git a/test/doctest.hs b/test/doctest.hs
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--- /dev/null
+++ b/test/doctest.hs
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+import Prelude
+import Test.DocTest
+
+main :: IO ()
+main = doctest ["src"]