static: make Entry a setting type

In the future we might want to add new features to the
Entry.  I am currently thinking about source maps, where
a new field will need to be added to the Entry.  Therefore,
use Data.Default to make sure we don't need to bump the
major version for these features.

yesod-static/Yesod/EmbeddedStatic/Generators.hs

@@ -37,6 +37,7 @@ import Control.Monad.Trans.Resource (runResourceT)
 import Data.Char (isDigit, isLower)
 import Data.Conduit (($$), (=$))
 import Data.Conduit.Process (proc, conduitProcess)
+import Data.Default (def)
 import Language.Haskell.TH
 import Network.Mime (defaultMimeLookup)
 import System.Directory (doesDirectoryExist, getDirectoryContents)
@@ -61,13 +62,12 @@ embedFile f = embedFileAt f f
 embedFileAt :: Location -> FilePath -> Generator
 embedFileAt loc f = do
     let mime = defaultMimeLookup $ T.pack f
-    let entry = Entry {
+    let entry = def {
                     ebHaskellName = Just $ pathToName loc
                   , ebLocation = loc
                   , ebMimeType = mime
                   , ebProductionContent = BL.readFile f
                   , ebDevelReload = [| BL.readFile $(litE $ stringL f) |]
-                  , ebDevelExtraFiles = Nothing
                   }
     return [entry]
 
@@ -148,7 +148,12 @@ concatFilesWith loc process files = do
         expFiles = listE $ map (litE . stringL) files
         expCt = [| BL.concat <$> mapM BL.readFile $expFiles |]
         mime = defaultMimeLookup $ T.pack loc
-    return [Entry (Just $ pathToName loc) loc mime load expCt Nothing]
+    return [def { ebHaskellName = Just $ pathToName loc
+                , ebLocation = loc
+                , ebMimeType = mime
+                , ebProductionContent = load
+                , ebDevelReload = expCt
+                }]
 
 -- | Convienient rexport of 'minifym' with a type signature to work with 'concatFilesWith'.
 jasmine :: BL.ByteString -> IO BL.ByteString
@@ -242,6 +247,7 @@ pathToName f = routeName
 -- >module CompileTime where
 -- >
 -- >import Data.Aeson
+-- >import Data.Default
 -- >import Data.Time
 -- >import Yesod.EmbeddedStatic.Generators
 -- >import Yesod.EmbeddedStatic.Types
@@ -255,13 +261,12 @@ pathToName f = routeName
 -- >
 -- >timeGenerator :: Location -> Generator
 -- >timeGenerator loc =
--- >    return $ [Entry
+-- >    return $ [def
 -- >        { ebHaskellName = Just $ pathToName loc
 -- >        , ebLocation    = loc
 -- >        , ebMimeType    = "application/json"
 -- >        , ebProductionContent = getTime
 -- >        , ebDevelReload = [| getTime |]
--- >        , ebDevelExtraFiles = Nothing
 -- >        }]
 --
 -- Notice how the @getTime@ action is given as both 'ebProductionContent' and

yesod-static/Yesod/EmbeddedStatic/Types.hs

@@ -1,9 +1,18 @@
+{-# LANGUAGE TemplateHaskell, QuasiQuotes, OverloadedStrings #-}
 module Yesod.EmbeddedStatic.Types(
     Location
-  , Entry(..)
   , Generator
+  -- ** Entry
+  , Entry
+  , ebHaskellName
+  , ebLocation
+  , ebMimeType
+  , ebProductionContent
+  , ebDevelReload
+  , ebDevelExtraFiles
 ) where
 
+import Data.Default
 import Language.Haskell.TH
 import Network.Mime (MimeType)
 import qualified Data.ByteString.Lazy as BL
@@ -13,6 +22,9 @@ import qualified Data.ByteString.Lazy as BL
 type Location = String
 
 -- | A single resource embedded into the executable at compile time.
+--
+-- This data type is a settings type.  For more information, see
+-- <http://www.yesodweb.com/book/settings-types>.
 data Entry = Entry {
     ebHaskellName :: Maybe Name
         -- ^ An optional haskell name. If the name is present, a variable
@@ -41,5 +53,15 @@ data Entry = Entry {
         --   and content.
 }
 
+-- | When using 'def', you must fill in at least 'ebLocation'.
+instance Default Entry where
+    def = Entry { ebHaskellName = Nothing
+                , ebLocation = "xxxx"
+                , ebMimeType = "application/octet-stream"
+                , ebProductionContent = return BL.empty
+                , ebDevelReload = [| return BL.empty |]
+                , ebDevelExtraFiles = Nothing
+                }
+
 -- | An embedded generator is executed at compile time to produce the entries to embed.
 type Generator = Q [Entry]

yesod-static/test/EmbedTestGenerator.hs

@@ -1,6 +1,7 @@
 {-# LANGUAGE TemplateHaskell, QuasiQuotes, OverloadedStrings #-}
 module EmbedTestGenerator (testGen) where
 
+import Data.Default
 import Network.Mime (MimeType)
 import Yesod.EmbeddedStatic.Types
 import Yesod.EmbeddedStatic.Generators (pathToName)
@@ -13,7 +14,7 @@ import qualified Data.ByteString.Lazy as BL
 e1, e2, e3, e4 :: Entry
 
 -- Basic entry
-e1 = Entry
+e1 = def
         { ebHaskellName = Just $ pathToName "e1"
         , ebLocation = "e1"
         , ebMimeType = "text/plain"
@@ -23,7 +24,7 @@ e1 = Entry
         }
 
 -- Test simulated directory in location
-e2 = Entry
+e2 = def
         { ebHaskellName = Just $ pathToName "e2"
         , ebLocation = "dir/e2"
         , ebMimeType = "abcdef"
@@ -33,7 +34,7 @@ e2 = Entry
         }
 
 -- Test empty haskell name
-e3 = Entry
+e3 = def
         { ebHaskellName = Nothing
         , ebLocation = "xxxx/e3"
         , ebMimeType = "yyy"
@@ -48,7 +49,7 @@ devExtra ["dir", "dev2"] = return $ Just ("mime2", "dev2 content")
 devExtra _ = return Nothing
 
 -- Entry with devel extra files
-e4 = Entry
+e4 = def
         { ebHaskellName = Just $ pathToName "e4"
         , ebLocation = "e4"
         , ebMimeType = "text/plain"