fix path prefix

ssg/src/Main.hs

@@ -69,7 +69,7 @@ main = hakyllWith config $ do
   match "posts/*" $ do
     let ctx = constField "type" "article" <> postCtx
 
-    route $  constRoute "posts/" <> metadataRoute titleRoute
+    route $ metadataRoute titleRoute `composeRoutes` (prefixRoute "posts/")
     compile $
       pandocCompilerCustom
         >>= loadAndApplyTemplate "templates/post.html" ctx
@@ -240,3 +240,6 @@ fileNameFromTitle =
 titleRoute :: Metadata -> Routes
 titleRoute =
   constRoute . fileNameFromTitle
+
+prefixRoute :: FilePath -> Routes
+prefixRoute p = customRoute $ \id -> p ++ (toFilePath id)