Expr trimming. '-' binds to '$'.

1 files changed, 9 insertions, 2 deletions

diff --git a/src/Hakyll/Core/Util/Parser.hs b/src/Hakyll/Core/Util/Parser.hs
index e958b76..c4b2f8d 100644
--- a/src/Hakyll/Core/Util/Parser.hs
+++ b/src/Hakyll/Core/Util/Parser.hs
@@ -8,7 +8,7 @@ module Hakyll.Core.Util.Parser
 
 --------------------------------------------------------------------------------
 import           Control.Applicative ((<|>))
-import           Control.Monad       (mzero)
+import           Control.Monad       (guard, mzero, void)
 import qualified Text.Parsec         as P
 import           Text.Parsec.String  (Parser)
 
@@ -16,7 +16,14 @@ import           Text.Parsec.String  (Parser)
 --------------------------------------------------------------------------------
 metadataKey :: Parser String
 metadataKey = do
-    i <- (:) <$> P.letter <*> (P.many $ P.alphaNum <|> P.oneOf "_-.")
+    -- Ensure trailing '-' binds to '$' if present.
+    let hyphon = P.try $ do
+            void $ P.char '-'
+            x <- P.lookAhead P.anyChar
+            guard $ x /= '$'
+            pure '-'
+
+    i <- (:) <$> P.letter <*> P.many (P.alphaNum <|> P.oneOf "_." <|> hyphon)
     if i `elem` reservedKeys then mzero else return i