Missing characters using Text.Regex.PCRE to parse web page title - regex

Question

I recently made a website that needs to retrieve talk titles from TED website.
So far, the problem is specific to this talk: Francis Collins: We need better drugs -- now
From the web page source, I get:
<title>Francis Collins: We need better drugs -- now | Video on TED.com</title>
<span id="altHeadline" >Francis Collins: We need better drugs -- now</span>
Now, in ghci, I tried this:
λ> :m +Network.HTTP Text.Regex.PCRE
λ> let uri = "http://www.ted.com/talks/francis_collins_we_need_better_drugs_now.html"
λ> body <- (simpleHTTP $ getRequest uri) >>= getResponseBody
λ> body =~ "<span id=\"altHeadline\" >(.+)</span>" :: [[String]]
[["id=\"altHeadline\" >Francis Collins: We need better drugs -- now</span>\n\t\t</h","s Collins: We need better drugs -- now</span"]]
λ> body =~ "<title>(.+)</title>" :: [[String]]
[["tle>Francis Collins: We need better drugs -- now | Video on TED.com</title>\n<l","ncis Collins: We need better drugs -- now | Video on TED.com</t"]]
Either way, the parsed title misses some characters on the left, and has some unintended characters on the right. It seems to have something to do with the -- in talk title. However,
λ> let body' = "<title>Francis Collins: We need better drugs -- now | Video on TED.com</title>"
λ> body' =~ "<title>(.+)</title>" :: [[String]]
[["<title>Francis Collins: We need better drugs -- now | Video on TED.com</title>","Francis Collins: We need better drugs -- now | Video on TED.com"]]
Luckily, this is not a problem with Text.Regex.Posix.
λ> import qualified Text.Regex.Posix as P
λ> body P.=~ "<title>(.+)</title>" :: [[String]]
[["<title>Francis Collins: We need better drugs -- now | Video on TED.com</title>","Francis Collins: We need better drugs -- now | Video on TED.com"]]

Answer 1

My recommendation would be: don't use a regex for parsing HTML. Use a proper HTML parser instead. Here's an example using the html-conduit parser together with the xml-conduit cursor library (and http-conduit for download).
{-# LANGUAGE OverloadedStrings #-}
import Data.Monoid (mconcat)
import Network.HTTP.Conduit (simpleHttp)
import Text.HTML.DOM (parseLBS)
import Text.XML.Cursor (attributeIs, content, element,
fromDocument, ($//), (&//), (>=>))
main = do
lbs <- simpleHttp "http://www.ted.com/talks/francis_collins_we_need_better_drugs_now.html"
let doc = parseLBS lbs
cursor = fromDocument doc
print $ mconcat $ cursor $// element "title" &// content
print $ mconcat $ cursor $// element "span" >=> attributeIs "id" "altHeadline" &// content
The code is also available as active code on the School of Haskell.