diff --git a/Data/Filtrable.hs b/Data/Filtrable.hs
--- a/Data/Filtrable.hs
+++ b/Data/Filtrable.hs
@@ -4,6 +4,7 @@
 
 import Control.Applicative
 import Control.Monad
+import Data.Bool (bool)
 import Data.Proxy
 import Data.Traversable
 
@@ -15,7 +16,7 @@
 --
 -- * @'catMaybes' = 'mapMaybe' id@
 --
--- * @'filter' f = 'mapMaybe' ('liftA2' ('<$') id ('guard' ∘ f))@
+-- * @'filter' f = 'mapMaybe' (\\ x -> 'bool' 'Nothing' ('Just' x) (f x))@
 class Functor f => Filtrable f where
     {-# MINIMAL mapMaybe | catMaybes #-}
 
diff --git a/filtrable.cabal b/filtrable.cabal
--- a/filtrable.cabal
+++ b/filtrable.cabal
@@ -1,5 +1,5 @@
 name:                filtrable
-version:             0.1.0.2
+version:             0.1.0.3
 synopsis:            Class of filtrable containers
 homepage:            https://github.com/strake/filtrable.hs
 license:             OtherLicense