diff --git a/Data/Constraint.hs b/Data/Constraint.hs
new file mode 100644
--- /dev/null
+++ b/Data/Constraint.hs
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+module Data.Constraint where
+
+import Prelude hiding (Functor, (.), id)
+
+import Control.Categorical.Functor
+import Control.Category
+
+data Dict a where Dict :: a => Dict a
+
+deriving instance Eq (Dict a)
+deriving instance Ord (Dict a)
+deriving instance a => Read (Dict a)
+deriving instance Show (Dict a)
+deriving instance a => Bounded (Dict a)
+
+instance a => Enum (Dict a) where
+    toEnum _ = Dict
+    fromEnum Dict = 0
+
+instance Semigroup (Dict a) where Dict <> Dict = Dict
+instance a => Monoid (Dict a) where
+    mempty = Dict
+    mappend = (<>)
+
+withDict :: Dict a -> (a => b) -> b
+withDict Dict b = b
+
+newtype a :- b = Sub (a => Dict b)
+
+instance Eq (a :- b) where Sub _ == Sub _ = True
+instance Ord (a :- b) where Sub _ `compare` Sub _ = EQ
+instance Show (a :- b) where showsPrec p (Sub _) = showParen (p > 10) $ showString "Sub Dict"
+
+instance Category (:-) where
+    id = Sub Dict
+    Sub c . Sub b = Sub (withDict b c)
+
+instance Functor (:-) (->) Dict where map (Sub a) Dict = withDict a Dict
+
+unmapDict :: (Dict a -> Dict b) -> a :- b
+unmapDict f = Sub (f Dict)
diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright (c) 2017, M Farkas-Dyck
+
+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 M Farkas-Dyck 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
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/constraint.cabal b/constraint.cabal
new file mode 100644
--- /dev/null
+++ b/constraint.cabal
@@ -0,0 +1,28 @@
+name:                constraint
+version:             0.1.0.0
+synopsis:            Reified constraints
+-- description:         
+license:             BSD3
+license-file:        LICENSE
+author:              M Farkas-Dyck
+maintainer:          m.farkasdyck@gmail.com
+-- copyright:           
+category:            Constraint
+build-type:          Simple
+cabal-version:       >=1.10
+
+library
+  exposed-modules:     Data.Constraint
+  -- other-modules:       
+  -- other-extensions:    
+  build-depends:       base >=4.10 && <4.12
+                     , category >=0.1.2
+  -- hs-source-dirs:      
+  default-language:    Haskell2010
+  default-extensions:  TypeOperators
+                     , RankNTypes
+                     , PolyKinds
+                     , ConstraintKinds
+                     , MultiParamTypeClasses
+                     , GADTs
+                     , StandaloneDeriving