Add configGet for convenience

At the cost of safety. :'-(

Signed-off-by: Jan Hamal Dvořák <mordae@anilinux.org>

lib/Hikaru/Config.hs

@@ -27,6 +27,7 @@ module Hikaru.Config
   , configDefault
 
   -- * Reading Config
+  , configGet
   , configGetMaybe
   , configGetDefault
 
@@ -107,6 +108,16 @@ where
                           ]
 
 
+  -- |
+  -- Obtain value of a configuration key or raise an error.
+  -- You really should not use this function, you know?
+  --
+  configGet :: (Param a) => Text -> Config -> a
+  configGet name cfg = case configGetMaybe name cfg of
+                         Just value -> value
+                         Nothing -> error (name <> " not set!")
+
+
   -- |
   -- Try to obtain value of a configuration key.
   --