Simplify the the filter interface by hidding internals

changelog

@@ -3,7 +3,9 @@
 v0.2 December 2014
  BREAKING CHANGES:
    * Origin is on the upper left corner of the image (was bottom left).
-   * New Filter interface.
+   * New simplified filters interface. The old interface is still used
+     internally to create filters and is available in
+     Vision.Image.Filter.Internal.
    * DevIL bindings (Vision.Image.Storage) are now in a separate package
      (friday-devil) and with an improved interface.
    * Benchmarks are now in a separate package (friday-bench).

friday.cabal

@@ -45,6 +45,7 @@ library
                         Vision.Image.Grey.Specialize
                         Vision.Image.Grey.Type
                         Vision.Image.Filter
+                        Vision.Image.Filter.Internal
                         Vision.Image.HSV
                         Vision.Image.HSV.Conversion
                         Vision.Image.HSV.Specialize

src/Vision/Detector/Edge.hs

@@ -1,4 +1,6 @@
-{-# LANGUAGE BangPatterns, FlexibleContexts, MultiWayIf #-}
+{-# LANGUAGE BangPatterns
+           , FlexibleContexts
+           , MultiWayIf #-}
 
 module Vision.Detector.Edge (canny) where
 
@@ -12,7 +14,7 @@ import Vision.Image (
       Image, ImagePixel, Manifest, MutableManifest, Grey, DerivativeType (..)
     , (!), shape, linearIndex, fromFunction
     , create, new', linearRead, linearWrite
-    , apply, sobel
+    , sobel
     )
 import Vision.Primitive (Z (..), (:.) (..), inShape, ix2)
 
@@ -64,8 +66,8 @@ canny !derivSize !lowThres !highThres !img =
     (!lowThres', !highThres') = (square lowThres, square highThres)
 
     dx, dy :: Manifest Int16
-    !dx = sobel derivSize DerivativeX `apply` img
-    !dy = sobel derivSize DerivativeY `apply` img
+    !dx = sobel derivSize DerivativeX img
+    !dy = sobel derivSize DerivativeY img
 
     -- Gradient magnitude, squared.
     dxy :: Manifest Int32

src/Vision/Histogram.hs

@@ -1,5 +1,9 @@
-{-# LANGUAGE BangPatterns, FlexibleContexts, FlexibleInstances
-           , ParallelListComp, TypeFamilies, TypeOperators #-}
+{-# LANGUAGE BangPatterns
+           , FlexibleContexts
+           , FlexibleInstances
+           , ParallelListComp
+           , TypeFamilies
+           , TypeOperators #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 
 -- | Contains functions to compute and manipulate histograms as well as some