1 files changed, 8 insertions, 1 deletions
diff --git a/src/Hakyll/Web/Template/Util.hs b/src/Hakyll/Web/Template/Util.hs
index cfd8573..f08c041 100644
--- a/src/Hakyll/Web/Template/Util.hs
+++ b/src/Hakyll/Web/Template/Util.hs
@@ -1,11 +1,18 @@
 module Hakyll.Web.Template.Util
-    ( slug
+    ( functionField1
+    , slug
     ) where
 
 import Prolog
+import Hakyll
 import Hakyll.Web.Template.Context
 import Data.String.Slugger
+import System.FilePath
 
+functionField1 :: String -> (String -> Compiler String) -> Context a
+functionField1 n f = functionField n $ \case
+    [x] -> \_ -> f x
+    xs -> \_ -> fail $ "Expecting exactly one argument to " <> n <> ". Instead got " <> show (length xs)
 
 slug :: Context a
 slug = functionField "slug" $ \strs _ -> pure $ toSlug $ unwords strs