diff --git a/COPYING b/COPYING
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--- /dev/null
+++ b/COPYING
@@ -0,0 +1,26 @@
+
+Copyright (c) 2013, Hans Höglund
+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 the <organization> nor the
+      names of its 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 <COPYRIGHT HOLDER> 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
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--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,4 @@
+#! /usr/bin/env runhaskell
+
+import Distribution.Simple
+main = defaultMain
diff --git a/positive.cabal b/positive.cabal
new file mode 100644
--- /dev/null
+++ b/positive.cabal
@@ -0,0 +1,28 @@
+
+name:               positive
+version:            0.1
+cabal-version:      >= 1.10
+author:             Hans Hoglund
+maintainer:         Hans Hoglund <hans@hanshoglund.se>
+license:            BSD3
+license-file:       COPYING
+synopsis:           Positive numbers.
+category:           
+tested-with:        GHC
+build-type:         Simple
+
+description:
+    To be written.
+
+source-repository head
+    type:               git
+    location:           git://github.com/hanshoglund/foobar.git
+
+library
+    build-depends:
+        base            >= 4 && < 5,
+        nats            >= 0.2 && < 1
+    hs-source-dirs:     src
+    default-language:   Haskell2010
+    exposed-modules:
+        Numeric.Positive
diff --git a/src/Numeric/Positive.hs b/src/Numeric/Positive.hs
new file mode 100644
--- /dev/null
+++ b/src/Numeric/Positive.hs
@@ -0,0 +1,55 @@
+
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+
+module Numeric.Positive (
+        Positive,
+        positive
+  ) where
+import Numeric.Natural
+
+newtype Positive = Positive { getPositive :: Natural } deriving
+    ( 
+    Eq,
+    Ord,
+    -- Data,
+    Real,
+    -- Ix,
+    -- Typeable,
+    -- Bits,
+    -- Hashable,
+    Whole
+    )
+
+instance Show Positive where
+  show (Positive n) = show n
+
+instance Read Positive where
+  readsPrec d = map (\(n, s) -> (fromInteger n, s)) . readsPrec d
+
+instance Integral Positive where
+  toInteger (Positive a) = toInteger a
+  Positive a `quotRem` Positive b = (fromIntegral $ a `quot` b, fromIntegral $ a `rem` b)
+
+instance Enum Positive where
+  toEnum   = fromIntegral
+  fromEnum = fromIntegral
+  
+instance Num Positive where
+  Positive n + Positive m = Positive (n + m)
+  Positive n * Positive m = Positive (n * m)
+  Positive n - Positive m
+    | r <  0 = error "Positive.(-): negative result"
+    | r == 0 = error "Positive.(-): result zero"
+    | otherwise   = Positive r
+    where
+      r = n - m
+  abs      = id
+  signum _ = 1
+  fromInteger n
+    | n >  0 = Positive (fromInteger n)
+    | n == 0 = error "Positive.fromInteger: zero"
+    | n <  0 = error "Positive.fromInteger: negative"
+
+positive :: a -> (a -> a) -> Positive -> a
+positive a f 1 = f a
+positive a f n = f (positive a f $ pred n)