Compatibility with Octopress site.

Don't break urls.
 1. New Route function which generates routes compatible with old blog.
 2. Renamed posts folder to blog.

blogng.cabal

@@ -7,5 +7,7 @@ executable site
   main-is:          site.hs
   build-depends:    base == 4.*
                   , hakyll == 4.9.*
+                  , filepath >= 1.4
+                  , regex-compat
   ghc-options:      -threaded
   default-language: Haskell2010

site.hs

@@ -2,6 +2,10 @@
 {-# LANGUAGE OverloadedStrings #-}
 import           Data.Monoid (mappend)
 import           Hakyll
+import           Hakyll.Core.Identifier (toFilePath)
+import           System.FilePath
+import           Text.Regex (splitRegex, mkRegex)
+
 
 
 --------------------------------------------------------------------------------
@@ -21,8 +25,8 @@ main = hakyll $ do
             >>= loadAndApplyTemplate "templates/default.html" defaultContext
             >>= relativizeUrls
 
-    match "posts/*" $ do
-        route $ setExtension "html"
+    match "blog/*" $ do
+        route $  octopressRoute
         compile $ pandocCompiler
             >>= loadAndApplyTemplate "templates/post.html"    postCtx
             >>= loadAndApplyTemplate "templates/default.html" postCtx
@@ -31,7 +35,7 @@ main = hakyll $ do
     create ["archive.html"] $ do
         route idRoute
         compile $ do
-            posts <- recentFirst =<< loadAll "posts/*"
+            posts <- recentFirst =<< loadAll "blog/*"
             let archiveCtx =
                     listField "posts" postCtx (return posts) `mappend`
                     constField "title" "Archives"            `mappend`
@@ -46,7 +50,7 @@ main = hakyll $ do
     match "index.html" $ do
         route idRoute
         compile $ do
-            posts <- recentFirst =<< loadAll "posts/*"
+            posts <- recentFirst =<< loadAll "blog/*"
             let indexCtx =
                     listField "posts" postCtx (return posts) `mappend`
                     constField "title" "Home"                `mappend`
@@ -65,3 +69,18 @@ postCtx :: Context String
 postCtx =
     dateField "date" "%B %e, %Y" `mappend`
     defaultContext
+
+-- octopress compatible routes
+octopressRoute :: Routes
+octopressRoute = customRoute $ octoMangaling
+
+octoMangaling :: Identifier -> FilePath
+octoMangaling pathId = base </> year </> month </> day </> post </> "index.html"
+  where
+    p = toFilePath pathId
+    base = takeDirectory p
+    seps = splitRegex (mkRegex "-") $ takeBaseName p
+    year:month:day:xs = seps
+    post = tail $ foldl (\a b -> a ++ "-" ++ b) "" xs
+
+