diff --git a/semiring-simple.cabal b/semiring-simple.cabal
--- a/semiring-simple.cabal
+++ b/semiring-simple.cabal
@@ -1,54 +1,25 @@
 -- Initial semiring.cabal generated by cabal init.  For further 
 -- documentation, see http://haskell.org/cabal/users-guide/
 
--- The name of the package.
 name:                semiring-simple
-
--- The package version.  See the Haskell package versioning policy (PVP) 
--- for standards guiding when and how versions should be incremented.
--- http://www.haskell.org/haskellwiki/Package_versioning_policy
--- PVP summary:      +-+------- breaking API changes
---                   | | +----- non-breaking API additions
---                   | | | +--- code changes with no API change
-version:             0.2.0.0
-
--- A short (one-line) description of the package.
+version:             0.2.1.0
 synopsis:            A module for dealing with semirings.
-
--- A longer description of the package.
-description:         Semirings are like normal rings, except you can't subtract. This library provides a type class for semirings.
-
--- The license under which the package is released.
+description:
+  Semirings are like normal rings, except you can't subtract. This library
+  provides a type class for semirings.
 license:             BSD3
-
--- The file containing the license text.
 license-file:        LICENSE
-
--- The package author(s).
 author:              Thomas Wilke, Frank Huch, Sebastian Fischer, Peter Harpending
-
--- An email address to which users can send suggestions, bug reports, and 
--- patches.
-maintainer:          pharpend2@gmail.com
-
--- A copyright notice.
--- copyright:           2014
-
+maintainer:          Peter Harpending <pharpend2@gmail.com>
+copyright:           2014, Peter Harpending.
 category:            Math
-
 build-type:          Simple
-
--- Extra files to be distributed with the package, such as examples or a 
--- README.
 extra-source-files:  README.md
-
--- Constraint on the version of Cabal needed to build this package.
 cabal-version:       >=1.10
 
-
 library
-  -- Modules exported by the library.
-  exposed-modules:     Data.Semiring
+  exposed-modules:
+      Data.Semiring
   
   -- Modules included in this library but not exported.
   -- other-modules:       
@@ -57,7 +28,8 @@
   -- other-extensions:    
   
   -- Other library packages from which modules are imported.
-  build-depends:       base >=4.7 && <4.8
+  build-depends:
+      base >=4 && <5
   
   -- Directories containing source files.
   hs-source-dirs:      src/
@@ -65,7 +37,6 @@
   -- Base language which the package is written in.
   default-language:    Haskell2010
   
-
 source-repository head
   type:       git
   location:   https://github.com/pharpend/semiring.git
diff --git a/src/Data/Semiring.hs b/src/Data/Semiring.hs
--- a/src/Data/Semiring.hs
+++ b/src/Data/Semiring.hs
@@ -1,15 +1,24 @@
-{-| 
-Module      : Data.Semiring
-Copyright   : Thomas Wilke, Frank Huch, Sebastian Fischer, Peter Harpending
-License     : BSD3
-Maintainer  : Peter Harpending <pharpend2@gmail.com>
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE UndecidableInstances #-}
 
+{- |
+Module       : Data.Semiring.Tropical.Skel
+Description  : A module for Tropical whatever
+Copyright    : 2012, Thomas Wilke, Frank Huch, Sebastian Fischer
+               2014, Peter Harpending
+License      : BSD3
+Maintainer   : Peter Harpending <pharpend2@gmail.com>
+Stability    : experimental
+Portability  : archlinux
+
 This library provides a type class for semirings.
 
 -}
 
 module Data.Semiring where
 
+import Data.Monoid
+
 -- |
 -- A semiring is an additive commutative monoid with identity 'zero':
 -- 
@@ -32,6 +41,22 @@
 -- 
 -- > zero .*. a  ==  zero
 -- > a .*. zero  ==  zero
-class (Eq s) => Semiring s where
+class Semiring s where
   zero, one    :: s
   (.+.), (.*.) :: s -> s -> s
+
+instance Semiring a => Monoid a where
+  mempty = zero
+  mappend = (.+.)
+
+instance Num a => Semiring a where
+  zero = 0
+  one = 1
+  (.+.) = (+)
+  (.*.) = (*)
+
+instance Semiring Bool where
+  zero = False
+  one = True
+  (.+.) = (||)
+  (.*.) = (&&)