[Haskell-cafe] Re: Occurs check error, help!
ivan.miljenovic at gmail.com
Sun Mar 21 23:12:55 EDT 2010
On 22 March 2010 13:49, adamtheturtle <kill2thrill at hotmail.com> wrote:
> Just tried the code
> 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 I get:
> Could not deduce (Eq a) from the context ()
> arising from a use of `delete' at Cards.hs:(23,51)-(24,8)
> Possible fix:
> add (Eq a) to the context of the type signature for `shuffle'
> In the second argument of `shuffle', namely
> `(delete (cards !! i) cards)'
> In the second argument of `(:)', namely
> `shuffle (fst pair) (delete (cards !! i) cards)'
> In the expression:
> (cards !! i) : shuffle (fst pair) (delete (cards !! i) cards)
> Failed, modules loaded: none.
> Any ideas?
Yes: do what it says!
Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
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