ghc 7.10.1 RC1 requires specifying the type of String literals https://ghc.haskell.org/trac/ghc/wiki/Migration/7.10#GHCsaysNoinstanceforFoldable...arisingfromtheuseof...
commit8b9bded796b76a3f343c4cc1b8bb04a4b293ff55
authorMark Wright <gienah@gentoo.org>
dateMon 5 Jan 2015, 14:46 (12 years ago)
parente4c7894
src/Text/Pandoc/Writers/LaTeX.hs+1−1
@@ -240,7 +240,7 @@ toLabel z = go `fmap` stringToLaTeX URLString z
240240 where go [] = ""
241241 go (x:xs)
242242 | (isLetter x || isDigit x) && isAscii x = x:go xs
243− | elem x "-+=:;." = x:go xs
243+ | elem x ("-+=:;." :: String) = x:go xs
244244 | otherwise = "ux" ++ printf "%x" (ord x) ++ go xs
245245
246246-- | Puts contents into LaTeX command.