diff --git a/Control/Annihilator.hs b/Control/Annihilator.hs
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--- /dev/null
+++ b/Control/Annihilator.hs
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+
+-- | A class for Annihilators, which define a binary function '>|>' that follows
+-- the mathematical properties of: absorbing element, associativity, and
+-- commutativity.
+module Control.Annihilator
+    ( Annihilator(..)
+    , (<|<)
+    , aconcat
+    , amappend
+    , amconcat
+    , avoid
+    )
+    where
+
+-- | Annihilators are semigroups with annihilators, i.e. the
+-- following laws should hold:
+--
+-- prop> ann >|> b = ann
+-- prop> a >|> ann = ann
+-- prop> a >|> b = b
+class Annihilator a where
+    -- | Annihilating element of '>|>'.
+    ann :: a
+
+    -- | Annihilating operator, returns the rightmost element if no
+    -- annihilators 'ann' are present.
+    (>|>) :: a -> a -> a
+
+
+instance Annihilator () where
+    ann = ()
+
+    _ >|> _ = ()
+
+instance Annihilator (Maybe a) where
+    ann = Nothing
+
+    Nothing >|> _ = Nothing
+    _ >|> Nothing = Nothing
+    _ >|> a = a
+
+instance Annihilator ([] a) where
+    ann = []
+
+    [] >|> _ = []
+    _ >|> [] = []
+    _ >|> a = a
+
+instance (Annihilator a, Annihilator b) => Annihilator (a, b) where
+    ann = (ann, ann)
+
+    (a1, b1) >|> (a2, b2) = (a1 >|> a2, b1 >|> b2)
+
+
+-- | Flipped version of '>|>'.
+(<|<) :: Annihilator a => a -> a -> a
+(<|<) = flip (>|>)
+
+-- | Annihilating concatenation.
+aconcat :: (Annihilator a, Foldable t) => t a -> a
+aconcat as
+    | null as   = ann
+    | otherwise = foldr1 (>|>) as
+
+-- | Monadic append with the annihilating operator guarding each argument.
+amappend :: (Annihilator a, Monoid a) => a -> a -> a
+amappend a b = (a >|> b) `mappend` (a <|< b)
+
+-- | Monadic concatenation with the annihilating operator guarding each argument.
+amconcat :: (Annihilator a, Monoid a, Foldable t) => t a -> a
+amconcat as
+    | null as   = ann
+    | otherwise = foldr1 amappend as
+
+-- | Discard the argument and return 'ann'.
+avoid :: Annihilator a => a -> a
+avoid = const ann
+
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
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+Copyright Benedict Aas (c) 2016
+
+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 Author name here 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/Setup.hs b/Setup.hs
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--- /dev/null
+++ b/Setup.hs
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+import Distribution.Simple
+main = defaultMain
diff --git a/annihilator.cabal b/annihilator.cabal
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--- /dev/null
+++ b/annihilator.cabal
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+name:                annihilator
+version:             0.1.0.0
+synopsis:            Semigroups with annihilators and utility functions
+description:
+    Annihilators are semigroups with annihilators and therefore almost act as
+    the opposite of Alternative. This package comes with the typeclass and
+    utility functions.
+homepage:            http://github.com/Shou/annihilator#readme
+bug-reports:         http://github.com/Shou/annihilator/issues
+license:             BSD3
+license-file:        LICENSE
+author:              Benedict Aas
+maintainer:          x@shou.io
+copyright:           2016 Benedict Aas
+category:            Control 
+build-type:          Simple
+-- extra-source-files:
+cabal-version:       >=1.10
+tested-with:
+    GHC==7.10.3
+
+library
+  exposed-modules:     Control.Annihilator
+  build-depends:       base >= 4.7 && < 5
+  default-language:    Haskell2010
+
+source-repository head
+  type:     git
+  location: https://github.com/Shou/annihilator
+