diff --git a/Data/Digit.hs b/Data/Digit.hs
new file mode 100644
--- /dev/null
+++ b/Data/Digit.hs
@@ -0,0 +1,296 @@
+-- | A data type with ten nullary constructors and combinators.
+module Data.Digit
+(
+-- * Data type
+  Digit
+-- * Constructors
+, d0
+, d1
+, d2
+, d3
+, d4
+, d5
+, d6
+, d7
+, d8
+, d9
+-- * Deconstructors
+, foldDigit
+, if0
+, if1
+, if2
+, if3
+, if4
+, if5
+, if6
+, if7
+, if8
+, if9
+, ifEven
+, ifOdd
+) where
+
+-- | A data type with ten nullary constructors.
+data Digit =
+  D0
+  | D1
+  | D2
+  | D3
+  | D4
+  | D5
+  | D6
+  | D7
+  | D8
+  | D9
+  deriving (Eq, Ord, Enum, Bounded)
+
+instance Show Digit where
+  show = show . fromEnum
+
+instance Read Digit where
+  readsPrec _ ('0':t) =
+    [(d0, t)]
+  readsPrec _ ('1':t) =
+    [(d1, t)]
+  readsPrec _ ('2':t) =
+    [(d2, t)]
+  readsPrec _ ('3':t) =
+    [(d3, t)]
+  readsPrec _ ('4':t) =
+    [(d4, t)]
+  readsPrec _ ('5':t) =
+    [(d5, t)]
+  readsPrec _ ('6':t) =
+    [(d6, t)]
+  readsPrec _ ('7':t) =
+    [(d7, t)]
+  readsPrec _ ('8':t) =
+    [(d8, t)]
+  readsPrec _ ('9':t) =
+    [(d9, t)]
+  readsPrec _ _       =
+    []
+
+-- | Zero.
+d0 ::
+  Digit
+d0 =
+  D0
+
+-- | One.
+d1 ::
+  Digit
+d1 =
+  D1
+
+-- | Two.
+d2 ::
+  Digit
+d2 =
+  D2
+
+-- | Three.
+d3 ::
+  Digit
+d3 =
+  D3
+
+-- | Four.
+d4 ::
+  Digit
+d4 =
+  D4
+
+-- | Five.
+d5 ::
+  Digit
+d5 =
+  D5
+
+-- | Six.
+d6 ::
+  Digit
+d6 =
+  D6
+
+-- | Seven.
+d7 ::
+  Digit
+d7 =
+  D7
+
+-- | Eight
+d8 ::
+  Digit
+d8 =
+  D8
+
+-- | Nine.
+d9 ::
+  Digit
+d9 =
+  D9
+
+-- | Catamorphism for @Digit@.
+foldDigit ::
+  a -- ^ Zero.
+  -> a -- ^ One.
+  -> a -- ^ Two.
+  -> a -- ^ Three.
+  -> a -- ^ Four.
+  -> a -- ^ Five.
+  -> a -- ^ Six.
+  -> a -- ^ Seven.
+  -> a -- ^ Eight.
+  -> a -- ^ Nine.
+  -> Digit -- ^ The digit to fold.
+  -> a
+foldDigit d0 _  _  _  _  _  _  _  _  _  D0 =
+  d0
+foldDigit _  d1 _  _  _  _  _  _  _  _  D1 =
+  d1
+foldDigit _  _  d2 _  _  _  _  _  _  _  D2 =
+  d2
+foldDigit _  _  _  d3 _  _  _  _  _  _  D3 =
+  d3
+foldDigit _  _  _  _  d4 _  _  _  _  _  D4 =
+  d4
+foldDigit _  _  _  _  _  d5 _  _  _  _  D5 =
+  d5
+foldDigit _  _  _  _  _  _  d6 _  _  _  D6 =
+  d6
+foldDigit _  _  _  _  _  _  _  d7 _  _  D7 =
+  d7
+foldDigit _  _  _  _  _  _  _  _  d8 _  D8 =
+  d8
+foldDigit _  _  _  _  _  _  _  _  _  d9 D9 =
+  d9
+
+-- | Return the first argument if zero, otherwise the second argument.
+if0 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if0 t _ D0 =
+  t
+if0 _ f _ =
+  f
+
+-- | Return the first argument if one, otherwise the second argument.
+if1 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if1 t _ D1 =
+  t
+if1 _ f _ =
+  f
+
+-- | Return the first argument if two, otherwise the second argument.
+if2 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if2 t _ D2 =
+  t
+if2 _ f _ =
+  f
+
+-- | Return the first argument if three, otherwise the second argument.
+if3 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if3 t _ D3 =
+  t
+if3 _ f _ =
+  f
+
+-- | Return the first argument if four, otherwise the second argument.
+if4 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if4 t _ D4 =
+  t
+if4 _ f _ =
+  f
+
+-- | Return the first argument if five, otherwise the second argument.
+if5 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if5 t _ D5 =
+  t
+if5 _ f _ =
+  f
+
+-- | Return the first argument if six, otherwise the second argument.
+if6 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if6 t _ D6 =
+  t
+if6 _ f _ =
+  f
+
+-- | Return the first argument if seven, otherwise the second argument.
+if7::
+  x
+  -> x
+  -> Digit
+  -> x
+if7 t _ D7 =
+  t
+if7 _ f _ =
+  f
+
+-- | Return the first argument if eight, otherwise the second argument.
+if8 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if8 t _ D8 =
+  t
+if8 _ f _ =
+  f
+
+-- | Return the first argument if nine, otherwise the second argument.
+if9 ::
+  x
+  -> x
+  -> Digit
+  -> x
+if9 t _ D9 =
+  t
+if9 _ f _ =
+  f
+
+-- | Return the first argument if even, otherwise the second argument.
+ifEven ::
+  x
+  -> x
+  -> Digit
+  -> x
+ifEven t f =
+  foldDigit t f t f t f t f t f
+
+-- | Return the first argument if odd, otherwise the second argument.
+ifOdd ::
+  x
+  -> x
+  -> Digit
+  -> x
+ifOdd =
+  flip ifEven
+
diff --git a/Digit.cabal b/Digit.cabal
new file mode 100644
--- /dev/null
+++ b/Digit.cabal
@@ -0,0 +1,32 @@
+Name:               Digit
+Version:            0.0.1
+License:            BSD3
+License-File:       LICENSE
+Author:             Tony Morris <ʇǝu˙sıɹɹoɯʇ@ןןǝʞsɐɥ>
+Maintainer:         Tony Morris
+Synopsis:           A data-type representing digits 0-9
+Category:           Data
+Description:        A data-type with 10 nullary constructors
+Cabal-version:      >= 1.2
+Build-Type:         Simple
+
+Flag small_base
+  Description:      Choose the new, split-up base package.
+
+Library
+  Build-Depends:
+                    base < 5 && >= 4
+                    , HUnit
+                    , QuickCheck
+                    , test-framework
+                    , test-framework-hunit
+                    , test-framework-quickcheck2
+
+  GHC-Options:
+                    -Wall
+                    -fno-warn-name-shadowing
+                    -fno-warn-orphans
+
+  Exposed-Modules:
+                    Data.Digit
+                    , Test.Data.Digit
diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,27 @@
+Copyright 2010 Tony Morris
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+2. 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.
+3. Neither the name of the author nor the names of his contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 AUTHORS 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/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,3 @@
+import Distribution.Simple
+main = defaultMain
+
diff --git a/Test/Data/Digit.hs b/Test/Data/Digit.hs
new file mode 100644
--- /dev/null
+++ b/Test/Data/Digit.hs
@@ -0,0 +1,49 @@
+module Test.Data.Digit where
+
+import Data.Digit
+import Test.QuickCheck
+import Test.Framework
+import Test.Framework.Providers.QuickCheck2 (testProperty)
+
+instance Arbitrary Digit where
+  arbitrary = elements [d0 .. d9]
+
+main ::
+  IO ()
+main =
+  defaultMain digitTests
+
+digitTests ::
+  [Test]
+digitTests =
+  [
+    testGroup "Digit"
+      [
+        testProperty "fold for Digit"         prop_fold
+      , testProperty "fold for Digit with if" prop_if
+      , testProperty "even/odd Digit"         prop_even_odd
+      ]
+  ]
+
+prop_fold ::
+  Digit
+  -> Bool
+prop_fold d =
+  foldDigit d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 d == d
+
+prop_if ::
+  Int
+  -> Int
+  -> Digit
+  -> Bool
+prop_if x y d =
+  foldDigit if0 if1 if2 if3 if4 if5 if6 if7 if8 if9 d x y d == x
+
+prop_even_odd ::
+  Int
+  -> Int
+  -> Digit
+  -> Bool
+prop_even_odd x y d =
+  ifEven x y d == ifOdd y x d
+