[Haskell-cafe] Occurs check error, help!

boblettoj boblettoj99 at msn.com
Sat Mar 20 23:55:16 EDT 2010

newStdGen results in IO Ints whereas i need normal Ints and it seems theres
no easy way to convert them without a lot more knowledge of haskell. I have
tried using a where clause instead of using do but this is giving me the
occurs check error again!

--function used to shuffle cards 
--list equals random member of array plus the rest of the array
--i is randomly generated from range of length equal to that of cards.
shuffle :: Int -> [a] -> [a]
shuffle i [] = []
shuffle i cards = [(cards!!i) : shuffle (fst pair) (delete (cards!!i)
	where pair = randomR (0, 51) (mkStdGen 42)

and the error:
    Occurs check: cannot construct the infinite type: a = [a]
    When generalising the type(s) for `shuffle'
Failed, modules loaded: none.

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