[Haskell-beginners] Re: type def messes up

26 Jun 2010

      On Sat, 26 Jun 2010 22:18:35 +0200
Daniel Fischer  wrote:
...
It refers to the Haskell-1.3 report.
There have been many changes in the language since then.
ok thx for the warning.
i'm starting to notice some issues.

also thx for the tips in your other post daniel.

here's a specific item i was referring to:

ndmPapers :: IO ()
ndmPapers = do
        tags <- fmap parseTags $ openURL
"http://community.haskell.org/~ndm/downloads/" let papers = map f $
sections (~== "<li class=paper>") tags putStr $ unlines papers
    where
        f :: [Tag] -> String
        f xs = fromTagText (xs !! 2)
http://community.haskell.org/~ndm/darcs/tagsoup/tagsoup.htm
at the bottom of the page: my papers (neil mitchell who wrote tagsoup
for haskell)

with the 
f :: [Tag] -> String
left in ghci croaks:

======
TagSoup.hs:66:14:
    `Tag' is not applied to enough type arguments
    Expected kind `*', but `Tag' has kind `* -> *'
    In the type signature for `f': f :: [Tag] -> String
    In the definition of `ndmPapers':
        ndmPapers = do { tags <- fmap parseTags
                               $ openURL
"http://community.haskell.org/~ndm/downloads/"; let papers = ...;
                           putStr $ unlines papers }
                  where
                      f :: [Tag] -> String
                      f xs = fromTagText (xs !! 2)
Failed, modules loaded: none.
======
(i'm guessing that Tag is some type defined in Text.HTML.TagSoup)

however, the program runs fine if i comment out the type def.

so i'm curious as to why this is so.

i can't do a :t on f getting a 'not in scope' error, i guess because it
is part of ndmPapers, but that seems strange to me.

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