Create a function to 'fallthrough parse' ie. try the second parser only

if the first one fails.

src/MdToHTML.hs

@@ -141,6 +141,12 @@ manyTillLazy p1 p2 = do
 parseTillEol :: ReadP String
 parseTillEol = manyTill get (void (char '\n') <++ eof)
 
+-- Takes a list of parsers. Returns a parser that will try them in
+-- order, moving to the next one only if the current one fails.
+fallthroughParser :: [ReadP a] -> ReadP a
+fallthroughParser [x] = x
+fallthroughParser (x : xs) = x <++ fallthroughParser xs
+
 -- ---------------
 
 -- Parse a markdown header, denoted by 1-6 #'s followed by some text, followed by EOL.