diff --git a/src/Data/Validity.hs b/src/Data/Validity.hs
--- a/src/Data/Validity.hs
+++ b/src/Data/Validity.hs
@@ -25,7 +25,6 @@
     > instance Validity Prime where
     >     isValid (Prime n) = isPrime n
     -}
-
 module Data.Validity
     ( Validity(..)
     , isInvalid
@@ -33,24 +32,32 @@
     , constructValidUnsafe
     ) where
 
-import           Data.Maybe (fromMaybe)
-
+import Data.Maybe (fromMaybe)
 
 -- | A class of types that have additional invariants defined upon them
 -- that aren't enforced by the type system
 class Validity a where
-    -- | Check whether a given value is a valid value.
-    isValid :: a -> Bool
+    isValid :: a -> Bool -- ^ Check whether a given value is a valid value.
 
-isInvalid :: Validity a => a -> Bool
+isInvalid
+    :: Validity a
+    => a -> Bool
 isInvalid = not . isValid
 
 -- | Any tuple of things is valid if both of its elements are valid
-instance (Validity a, Validity b) => Validity (a, b) where
+instance (Validity a, Validity b) =>
+         Validity (a, b) where
     isValid (a, b) = isValid a && isValid b
 
+-- | Any Either of things is valid if the contents are valid in either of the cases.
+instance (Validity a, Validity b) =>
+         Validity (Either a b) where
+    isValid (Left a) = isValid a
+    isValid (Right b) = isValid b
+
 -- | Any tuple of things is valid if all three of its elements are valid
-instance (Validity a, Validity b, Validity c) => Validity (a, b, c) where
+instance (Validity a, Validity b, Validity c) =>
+         Validity (a, b, c) where
     isValid (a, b, c) = isValid a && isValid b && isValid c
 
 -- | A list of things is valid if all of the things are valid.
@@ -58,14 +65,16 @@
 -- This means that the empty list is considered valid.
 -- If the empty list should not be considered valid as part of your custom data
 -- type, make sure to write a custom @Validity instance@
-instance Validity a => Validity [a] where
+instance Validity a =>
+         Validity [a] where
     isValid = all isValid
 
 -- | A Maybe thing is valid if the thing inside is valid or it's nothing
 -- It makes sense to assume that 'Nothing' is valid.
 -- If Nothing wasn't valid, you wouldn't have used a Maybe
 -- in the datastructure.
-instance Validity a => Validity (Maybe a) where
+instance Validity a =>
+         Validity (Maybe a) where
     isValid Nothing = True
     isValid (Just a) = isValid a
 
@@ -98,29 +107,32 @@
 -- * NaN is not valid.
 -- * Infinite values are not valid.
 instance Validity Float where
-    isValid d
-      =  not (isNaN d)
-      && not (isInfinite d)
+    isValid d = not (isNaN d) && not (isInfinite d)
 
 -- | NOT trivially valid:
 --
 -- * NaN is not valid.
 -- * Infinite values are not valid.
 instance Validity Double where
-    isValid d
-      =  not (isNaN d)
-      && not (isInfinite d)
+    isValid d = not (isNaN d) && not (isInfinite d)
 
 -- | Trivially valid
 instance Validity Integer where
     isValid = const True
 
 -- | Construct a valid element from an unchecked element
-constructValid :: Validity a => a -> Maybe a
-constructValid p = if isValid p then Just p else Nothing
+constructValid
+    :: Validity a
+    => a -> Maybe a
+constructValid p =
+    if isValid p
+        then Just p
+        else Nothing
 
 -- | Construct a valid element from an unchecked element, throwing 'error'
 -- on invalid elements.
-constructValidUnsafe :: (Show a, Validity a) => a -> a
-constructValidUnsafe p = fromMaybe (error $ show p ++ " is not valid") $ constructValid p
-
+constructValidUnsafe
+    :: (Show a, Validity a)
+    => a -> a
+constructValidUnsafe p =
+    fromMaybe (error $ show p ++ " is not valid") $ constructValid p
diff --git a/validity.cabal b/validity.cabal
--- a/validity.cabal
+++ b/validity.cabal
@@ -1,12 +1,18 @@
 name:                validity
-version:             0.3.0.4
+version:             0.3.1.1
 synopsis:            Validity typeclass
 description:
+  For more info, see <https://github.com/NorfairKing/validity the readme>.
+  .
   Note: There are companion instance packages for this library:
   .
   * <https://hackage.haskell.org/package/validity-text validity-text>
   .
+  * <https://hackage.haskell.org/package/validity-path validity-path>
+  .
   * <https://hackage.haskell.org/package/validity-containers validity-containers>
+  .
+  * <https://hackage.haskell.org/package/validity-bytestring validity-bytestring>
 
 homepage:            https://github.com/NorfairKing/validity#readme
 license:             MIT
@@ -14,16 +20,15 @@
 author:              Tom Sydney Kerckhove
 maintainer:          syd.kerckhove@gmail.com
 copyright:           Copyright: (c) 2016 Tom Sydney Kerckhove
-category:            Web
+category:            Validity
 build-type:          Simple
--- extra-source-files:
 cabal-version:       >=1.10
 
 library
   hs-source-dirs:      src
   exposed-modules:     Data.Validity
                      , Data.RelativeValidity
-  build-depends:       base >= 4 && < 5
+  build-depends:       base >= 4.8 && < 5
   default-language:    Haskell2010
 
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