(optionally) read config path from cmdline arguments

src/Breve/Settings.hs

@@ -29,10 +29,13 @@ createEmptyIfMissing file = do
   when (not exists) (writeFile file "")
 
 
-settings :: IO AppSettings
-settings = do
-  urlsPath   <- getUserDataFile   "breve" ""
-  configPath <- getUserConfigFile "breve" ""
+settings :: Maybe FilePath -> IO AppSettings
+settings path = do
+  configPath <- case path of
+    Just path -> return path
+    Nothing   -> getUserConfigFile "breve" ""
+
+  urlsPath  <- getUserDataFile   "breve" ""
 
   config  <- load [Required configPath]
   host    <- lookupDefault "localhost"                config "hostname"

src/Main.hs

@@ -5,8 +5,10 @@ import Breve.Settings
 import Breve.UrlTable
 
 import Data.Text          (Text, unpack)
+import Data.Maybe         (listToMaybe)
 import Control.Concurrent (forkIO)
 import Control.Monad
+import System.Environment (getArgs)
 
 import Web.Spock.Core
 import Network.Wai.Handler.WarpTLS (runTLS, TLSSettings)
@@ -28,7 +30,8 @@ forkIO' = fmap (const ()) . forkIO
 
 main :: IO ()
 main = do
-  AppSettings {..} <- settings
+  configPath       <- fmap listToMaybe getArgs
+  AppSettings {..} <- settings configPath
   table            <- load urlTable
 
   when (bindPort == 443) (forkIO' $ runTLSRedirect bindHost)