diff --git a/Data/Cased.hs b/Data/Cased.hs
new file mode 100644
--- /dev/null
+++ b/Data/Cased.hs
@@ -0,0 +1,68 @@
+
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE EmptyDataDecls #-}
+
+module Data.Cased (
+  Lower, Upper, Mixed, Yes, No,
+  IsUpperCased, IsLowerCased,
+  Cased(..),
+  Casing(..),
+
+  upperCased, lowerCased, mixedCased,
+  force
+) where
+
+import qualified Data.Text.Lazy as LT
+import qualified Data.Text as ST
+import qualified Data.Char as C
+
+data Lower
+data Upper
+data Mixed
+data Yes
+data No
+
+newtype Cased a b = Cased { fromCased :: b }
+                  deriving (Show, Eq, Ord)
+
+class Casing a where
+  toUpper :: a -> a
+  toLower :: a -> a
+
+instance Casing ST.Text where
+  toUpper = ST.toUpper
+  toLower = ST.toLower
+
+instance Casing LT.Text where
+  toUpper = LT.toUpper
+  toLower = LT.toLower
+
+instance Casing String where
+  toUpper = map C.toUpper
+  toLower = map C.toLower
+
+type family IsLowerCased a :: *
+type family IsUpperCased a :: *
+
+type instance IsUpperCased Upper = Yes
+type instance IsUpperCased Lower = No
+type instance IsUpperCased Mixed = No
+
+type instance IsLowerCased Lower = Yes
+type instance IsLowerCased Upper = No
+type instance IsLowerCased Mixed = No
+
+force :: (Cased Mixed b -> c) -> b -> c
+force f = f . mixedCased
+
+mixedCased :: a -> Cased Mixed a
+mixedCased = Cased
+
+upperCased :: (Casing b, IsUpperCased a ~ No) => Cased a b -> Cased Upper b
+upperCased = Cased . toUpper . fromCased
+
+lowerCased :: (Casing b, IsLowerCased a ~ No) => Cased a b -> Cased Lower b
+lowerCased = Cased . toLower . fromCased
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,20 @@
+Copyright (c) 2015 William Casarin
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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/cased.cabal b/cased.cabal
new file mode 100644
--- /dev/null
+++ b/cased.cabal
@@ -0,0 +1,29 @@
+-- Initial cased.cabal generated by cabal init.  For further documentation,
+--  see http://haskell.org/cabal/users-guide/
+
+name:                cased
+version:             0.1.0.0
+synopsis:            Track string casing in its type
+description:         Track string casing in its type
+homepage:            https://github.com/jb55/cased
+license:             MIT
+license-file:        LICENSE
+author:              William Casarin
+maintainer:          bill@casarin.me
+-- copyright:           
+category:            Text
+build-type:          Simple
+-- extra-source-files:  
+cabal-version:       >= 1.8
+
+source-repository head
+  type: git
+  location: https://github.com/jb55/cased
+
+library
+  exposed-modules:     Data.Cased
+  -- other-modules:       
+  other-extensions:    FlexibleInstances, TypeSynonymInstances, TypeFamilies, EmptyDataDecls
+  build-depends: base >=4.7 && <5
+               , text
+  -- hs-source-dirs: