[Haskell-cafe] Shouldn't this be lazy???

[Olivier Boudry]

On 6/22/07, David Roundy <droundy at darcs.net> wrote:
> Or make this lazy with:
>
> > main = do ...
> >           origLinks <- mapM (unsafeInterleaveIO . getLinksAfterImgByAttr ...) picLinks
> --
> David Roundy
> Department of Physics
> Oregon State University

Just for info I used your tip to bring laziness into the function that
fetches the URLs. Work great and lazy now!

-- | create sections from tag type and attribute
getSectionsByTypeAndAttr :: String -> (String, String) -> String -> IO [[Tag]]
getSectionsByTypeAndAttr tagType attr url = do
    tags <- unsafeInterleaveIO $ liftM parseTags $ openURL $ url
    (return . filterByTypeAndAttr tagType attr) tags
  where
    filterByTypeAndAttr :: String -> (String, String) -> [Tag] -> [[Tag]]
    filterByTypeAndAttr t a = sections (~== TagOpen t [a])

Thanks,

Olivier.