3 files changed, 45 insertions, 22 deletions
diff --git a/src/Hakyll/Core/Util/String.hs b/src/Hakyll/Core/Util/String.hs
index d9ec91c..b46f7b8 100644
--- a/src/Hakyll/Core/Util/String.hs
+++ b/src/Hakyll/Core/Util/String.hs
@@ -1,5 +1,5 @@
+--------------------------------------------------------------------------------
 -- | Miscellaneous string manipulation functions.
---
 module Hakyll.Core.Util.String
     ( trim
     , replaceAll
@@ -7,21 +7,24 @@ module Hakyll.Core.Util.String
     , needlePrefix
     ) where
 
+
+--------------------------------------------------------------------------------
 import Data.Char (isSpace)
 import Data.List (isPrefixOf)
 import Data.Maybe (listToMaybe)
-
 import Text.Regex.TDFA ((=~~))
 
+
+--------------------------------------------------------------------------------
 -- | Trim a string (drop spaces, tabs and newlines at both sides).
---
 trim :: String -> String
 trim = reverse . trim' . reverse . trim'
   where
     trim' = dropWhile isSpace
 
+
+--------------------------------------------------------------------------------
 -- | A simple (but inefficient) regex replace funcion
---
 replaceAll :: String              -- ^ Pattern
            -> (String -> String)  -- ^ Replacement (called on capture)
            -> String              -- ^ Source string
@@ -35,9 +38,10 @@ replaceAll pattern f source = replaceAll' source
                 (capture, after) = splitAt l tmp
             in before ++ f capture ++ replaceAll' after
 
+
+--------------------------------------------------------------------------------
 -- | A simple regex split function. The resulting list will contain no empty
 -- strings.
---
 splitAll :: String    -- ^ Pattern
          -> String    -- ^ String to split
          -> [String]  -- ^ Result
@@ -50,19 +54,24 @@ splitAll pattern = filter (not . null) . splitAll'
             in before : splitAll' (drop l tmp)
 
 
--- | Find the first instance of needle (must be non-empty) in
--- haystack. We return the prefix of haystack before needle is
--- matched.
+
+--------------------------------------------------------------------------------
+-- | Find the first instance of needle (must be non-empty) in haystack. We
+-- return the prefix of haystack before needle is matched.
 --
 -- Examples:
---   needlePrefix "cd" "abcde" = "ab"
---   needlePrefix "ab" "abc" = ""
---   needlePrefix "ab" "xxab" = "xx"
---   needlePrefix "a" "xx" = "xx"
 --
-needlePrefix :: String -> String -> String
-needlePrefix needle haystack = go haystack
+-- > needlePrefix "cd" "abcde" = "ab"
+--
+-- > needlePrefix "ab" "abc" = ""
+--
+-- > needlePrefix "ab" "xxab" = "xx"
+--
+-- > needlePrefix "a" "xx" = "xx"
+needlePrefix :: String -> String -> Maybe String
+needlePrefix needle haystack = go [] haystack
   where
-    go [] = []
-    go xss@(x:xs) | needle `isPrefixOf` xss = []
-                  | otherwise = x : go xs
+    go _   []                     = Nothing
+    go acc xss@(x:xs)
+        | needle `isPrefixOf` xss = Just $ reverse acc
+        | otherwise               = go (x : acc) xs
diff --git a/src/Hakyll/Web/Html.hs b/src/Hakyll/Web/Html.hs
index 58b5c43..3a0aa3b 100644
--- a/src/Hakyll/Web/Html.hs
+++ b/src/Hakyll/Web/Html.hs
@@ -30,6 +30,7 @@ import           System.FilePath                 (joinPath, splitPath,
 import           Text.Blaze.Html                 (toHtml)
 import           Text.Blaze.Html.Renderer.String (renderHtml)
 import qualified Text.HTML.TagSoup               as TS
+import           Network.URI                     (isUnreserved, escapeURIString)
 
 
 --------------------------------------------------------------------------------
@@ -98,9 +99,18 @@ renderTags' = TS.renderTagsOptions TS.renderOptions
 -- Result:
 --
 -- > "/foo/bar.html"
+--
+-- This also sanitizes the URL, e.g. converting spaces into '%20'
 toUrl :: FilePath -> String
-toUrl ('/' : xs) = '/' : xs
-toUrl url        = '/' : url
+toUrl url = case url of
+    ('/' : xs) -> '/' : sanitize xs
+    xs         -> '/' : sanitize xs
+  where
+    -- Everything but unreserved characters should be escaped as we are
+    -- sanitising the path therefore reserved characters which have a
+    -- meaning in URI does not appear. Special casing for `/`, because it has
+    -- a special meaning in FilePath as well as in URI.
+    sanitize = escapeURIString (\c -> c == '/' || isUnreserved c)
 
 
 --------------------------------------------------------------------------------
diff --git a/src/Hakyll/Web/Template/Context.hs b/src/Hakyll/Web/Template/Context.hs
index 3fde93b..ecf769d 100644
--- a/src/Hakyll/Web/Template/Context.hs
+++ b/src/Hakyll/Web/Template/Context.hs
@@ -242,9 +242,13 @@ modificationTimeFieldWith locale key fmt = field key $ \i -> do
 teaserField :: String           -- ^ Key to use
             -> Snapshot         -- ^ Snapshot to load
             -> Context String   -- ^ Resulting context
-teaserField key snapshot = field key $ \item ->
-    (needlePrefix teaserSeparator . itemBody) <$>
-    loadSnapshot (itemIdentifier item) snapshot
+teaserField key snapshot = field key $ \item -> do
+    body <- itemBody <$> loadSnapshot (itemIdentifier item) snapshot
+    case needlePrefix teaserSeparator body of
+        Nothing -> fail $
+            "Hakyll.Web.Template.Context: no teaser defined for " ++
+            show (itemIdentifier item)
+        Just t -> return t
 
 
 --------------------------------------------------------------------------------