diff --git a/src/Data/Validity.hs b/src/Data/Validity.hs
--- a/src/Data/Validity.hs
+++ b/src/Data/Validity.hs
@@ -31,7 +31,7 @@
     https://hackage.haskell.org/package/genvalidity ):
 
     > instance Validity Prime where
-    >     validate (Prime n) = isPrime n <?@> "The 'Int' is prime."
+    >     validate (Prime n) = check (isPrime n) "The 'Int' is prime."
 
     If certain typeclass invariants exist, you can make these explicit in the
     validity instance as well.
@@ -51,6 +51,8 @@
     , decorateList
     , invalid
     , valid
+    , validateNotNaN
+    , validateNotInfinite
     -- * Utilities
     -- ** Utilities for validity checking
     , isValid
@@ -61,6 +63,8 @@
     , Validation(..)
     , ValidationChain(..)
     , checkValidity
+    , validationIsValid
+    , prettyValidate
     , prettyValidation
     -- * Re-exports
     , Monoid(..)
@@ -424,28 +428,20 @@
 instance Validity Word64 where
     validate = trivialValidation
 
--- | NOT trivially valid:
---
--- * NaN is not valid.
--- * Infinite values are not valid.
+-- | Trivially valid:
 instance Validity Float where
-    validate f =
-        mconcat
-            [ declare "The Float is not NaN." $ not (isNaN f)
-            , declare "The Float is not infinite." $ not (isInfinite f)
-            ]
+    validate = trivialValidation
 
--- | NOT trivially valid:
---
--- * NaN is not valid.
--- * Infinite values are not valid.
+-- | Trivially valid:
 instance Validity Double where
-    validate d =
-        mconcat
-            [ declare "The Double is not NaN." $ not (isNaN d)
-            , declare "The Double is not infinite." $ not (isInfinite d)
-            ]
+    validate = trivialValidation
 
+validateNotNaN :: RealFloat a => a -> Validation
+validateNotNaN d = declare "The Double is not NaN." $ not (isNaN d)
+
+validateNotInfinite :: RealFloat a => a -> Validation
+validateNotInfinite d = declare "The Double is not infinite." $ not (isInfinite d)
+
 -- | Trivially valid
 --
 -- Integer is not trivially valid under the hood, but instantiating
@@ -547,12 +543,30 @@
         Validation [] -> Right a
         Validation errs -> Left errs
 
--- | validate a given value, and return a nice error if the value is invalid.
-prettyValidation :: Validity a => a -> Either String a
-prettyValidation a =
-    case checkValidity a of
-        Right a_ -> Right a_
-        Left errs -> Left $ intercalate "\n" $ map (errCascade . toStrings) errs
+-- | Check if a 'Validation' concerns a valid value.
+validationIsValid :: Validation -> Bool
+validationIsValid v = case v of
+    Validation [] -> True
+    _ -> False
+
+-- | Validate a given value
+--
+-- This function will return a nice error if the value is invalid.
+-- It will return the original value in 'Right' if it was valid,
+-- as evidence that it has been validated.
+prettyValidate :: Validity a => a -> Either String a
+prettyValidate a = case prettyValidation $ validate a of
+    Just e -> Left e
+    Nothing -> Right a
+
+-- | Render a `Validation` in a somewhat pretty way.
+--
+-- This function will return 'Nothing' if the 'Validation' concerned a valid value.
+prettyValidation :: Validation -> Maybe String
+prettyValidation v =
+    case v of
+        Validation [] -> Nothing
+        Validation errs -> Just $ intercalate "\n" $ map (errCascade . toStrings) errs
   where
     toStrings (Violated s) = ["Violated: " ++ s]
     toStrings (Location s vc) = s : toStrings vc
diff --git a/test/Data/ValiditySpec.hs b/test/Data/ValiditySpec.hs
--- a/test/Data/ValiditySpec.hs
+++ b/test/Data/ValiditySpec.hs
@@ -6,10 +6,11 @@
     ) where
 
 import GHC.Generics (Generic)
-#if !MIN_VERSION_base(4,11,0)
+#if !MIN_VERSION_base(4,7,0)
 import Data.Monoid
 #endif
 import Data.Validity
+import GHC.Real (Ratio(..))
 
 import Test.Hspec
 
@@ -25,38 +26,21 @@
             Fine -> valid
 
 data GeneratedValidity =
-    G Double
-      Double
+    G Rational
+      Rational
     deriving (Show, Eq, Generic)
 
 instance Validity GeneratedValidity
 
--- To make sure that the <?!> operator have the right fixity
-data ManuallyInstantiated =
-    M Double
-      Double
-    deriving (Show, Eq)
-
-instance Validity ManuallyInstantiated where
-    validate (M m1 m2) = annotate m1 "m1" <> annotate m2 "m2"
-
--- To make sure that the <?@> operator have the right fixity
-data TwoEvens =
-    E Int
-      Int
-    deriving (Show, Eq)
-
-instance Validity TwoEvens where
-    validate (E e1 e2) =
-        declare "e1 is even" (even e1) <> declare "e2 is even" (even e2)
-
 spec :: Spec
 spec = do
     describe "Wrong" $ do
         it "says Wrong is invalid" $ Wrong `shouldSatisfy` (not . isValid)
         it "says Fine is valid" $ Fine `shouldSatisfy` isValid
     describe "GeneratedValidity" $ do
-        let nan = read "NaN"
-        it "says G nan 0 is not valid" $ G nan 0 `shouldSatisfy` (not . isValid)
-        it "says G 0 nan is not valid" $ G 0 nan `shouldSatisfy` (not . isValid)
+        let nan = 1 :% 0
+        it "says G (1:%0) 0 is not valid" $
+            G nan 0 `shouldSatisfy` (not . isValid)
+        it "says G 0 (1:%0) is not valid" $
+            G 0 nan `shouldSatisfy` (not . isValid)
         it "says G 0 0 is valid" $ G 0 0 `shouldSatisfy` isValid
diff --git a/validity.cabal b/validity.cabal
--- a/validity.cabal
+++ b/validity.cabal
@@ -2,10 +2,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 2d73ea367f1418980c464539a285c39b7ca5b03e5c820533c8f375b156eb9f27
+-- hash: d7dbe113de14753bb19dacab5a6fad8e6ac1fd75f7d6157d10c29c478a6b267f
 
 name:           validity
-version:        0.8.0.0
+version:        0.9.0.0
 synopsis:       Validity typeclass
 description:    For more info, see <https://github.com/NorfairKing/validity the readme>.
                 .